Half-moon Hairstreak (Satyrium semilunar) Okanagan-Similkameen population, Waterton Lakes population: COSEWIC assessment and status report 2022

Official title: COSEWIC assessment and status report on the Half-moon Hairstreak (Satyrium semilunar) Okanagan-Similkameen population, Waterton Lakes population, in Canada

Okanagan-Similkameen population - Threatened
Waterton Lakes population - Endangered

2022

COSEWIC assessment summary

Assessment summary – December 2022

Common name: Half-moon Hairstreak – Okanagan-Similkameen population

Scientific name: Satyrium semiluna

Status: Threatened

Reason for designation: The butterfly occurs at fewer than 10 disjunct sites in southern British Columbia at the northern extreme of the species’ range. Changes in fire regime and invasion by non-native plants are reducing habitat quality, and some sites are under pressure from development. Combining these threats could reduce population size in the near future.

Occurrence: British Columbia

Status history: The species was considered a single unit and designated Endangered in April 2006. Split into two populations in December 2022. The Okanagan-Similkameen population was designated Threatened in December 2022.

Assessment summary – December 2022

Common name: Half-moon Hairstreak - Waterton Lakes population

Scientific name: Satyrium semiluna

Status: Endangered

Reason for designation: The butterfly is restricted to one small site in Waterton Lakes National Park in southern Alberta at the northern extreme of the species’ range and distant from any other sites. Population size is unknown, but very small, and has likely declined in the past as a result of habitat loss. An invasive plant, Spotted Knapweed, is an ongoing threat that reduces habitat quality and availability of nectar plants.

Occurrence: Alberta

Status history: The species was considered a single unit and designated Endangered in April 2006. Split into two populations in December 2022. The Waterton Lakes population was designated Endangered in December 2022.

COSEWIC executive summary

Half-moon Hairstreak

Satyrium semiluna

Okanagan-Similkameen population

Waterton Lakes population

Wildlife species description and significance

The Half-moon Hairstreak is in the large family Lycaenidae (gossamer-winged butterflies). Adults are small (2.5–3.4 cm wingspan) with the dorsal wing surfaces a uniform sooty brownish-black. In contrast with other hairstreaks, adults lack small extensions (‘tails’) on their hindwings. Sexes differ slightly, with females tending to be larger and paler than males. Half-moon Hairstreak is one of a group of butterflies that reach their northern distribution limit in southern Canada. There are no described subspecies; however, there is evidence for two designatable units: the Okanagan-Similkameen population and the Waterton Lakes population.

Distribution

Globally, the Half-moon Hairstreak ranges in western North America from south-central British Columbia (BC), south through eastern Washington, to northeastern California and northern Nevada. The eastern boundary extends from Colorado to Waterton Lakes National Park (WLNP) in Alberta (AB). Less than 1% of the species’ global range is in Canada.

In Canada, the Half-moon Hairstreak occurs as two designatable units (DU; also referred to as populations): the Okanagan-Similkameen population and the Waterton Lakes population. The Okanagan-Similkameen population occurs as six extant subpopulations in south central BC. The northernmost subpopulation is located southwest of Penticton in the White Lake basin, and the southernmost, about 6 km west of Osoyoos, adjacent to the United States border. The Waterton Lakes population is in WLNP, in extreme southwestern Alberta. There is one subpopulation and it is extant.

Habitat

In British Columbia, the Half-moon Hairstreak inhabits the dry Big Sagebrush / Bluebunch Wheatgrass ecological community, at an elevation of 600 to 1,000 m above sea level (asl), most with reduced relief in comparison to surrounding steeper areas. In Alberta, the species occurs only in the Blakiston Creek alluvial fan, which is dry grassland and aspen parkland, at an elevation of ~1290 m asl. The soils were formed on rapidly to moderately well‑drained, coarse-textured fluvial landforms.

Biology

The Half-moon Hairstreak has an annual life cycle and undergoes complete metamorphosis with four stages (egg, larva [four instars], pupa, and adult). Adults in the Okanagan-Similkameen population have been recorded from late May through early July, and those in the Waterton Lakes population, from early July to early August.

The caterpillars feed on lupines. For the Okanagan-Similkameen population, the host plants are likely Silky Lupine and Sulphur Lupine. For the Waterton Lakes population, the host plants are Silvery Silky Lupine. The presumed larval food plants are abundant and widespread in British Columbia and Alberta. The presence of these lupines does not limit the Half-moon Hairstreak’s range, as they have broader geographic ranges than that of the butterfly. With regard to nectar plants, Half-moon Hairstreak adults are likely opportunistic, with a perceived preference for buckwheat (Eriogonum spp.).

Numerous lycaenid butterflies in North America are myrmecophilous: there is a mutualism between ants (Formicidae) and caterpillars. The butterfly larvae secrete honeydew while feeding, which attracts ants; the ants then groom the larvae to obtain more honeydew. Larval secretions serve as food for ants, and the larvae secure ant defense against parasitoids. The mutualism between ants and Half-moon Hairstreak is being studied in WLNP and appears to involve both Lasius and wood ants.

Population sizes and trends

Half-moon Hairstreak adults have been recorded in Canada from 1895 to 2021. Surveys in both BC and AB have focused on recording new subpopulations, confirming threats and gathering information on natural history and habitats. The primary survey method consists of wandering transects through potential habitat and changing course where host and nectar plants are abundant. No information on Canadian population size or trends is available for either the Okanagan-Similkameen population or the Waterton Lakes populations

Threats and limiting factors

The primary threats to the Okanagan-Similkameen population are changes in larval plant abundance and nectar plant abundance due to ecosystem modifications associated with fire suppression, as well as the spread and continued introduction of invasive non-native, plants, and changes in the ecological community caused by domestic livestock grazing. Wildfires pose a direct threat to these same habitats.

The primary threat to the Waterton Lakes population is the spread of non-native plants, such as Spotted Knapweed. An increase in the abundance of knapweed reduces habitat quality by reducing the availability of the larval host plants (lupines) and nectar sources for adults.

Limiting factors include the presence and abundance of healthy larval host plants. The species’ larvae may depend on a mutualistic relationship with ants and, if that is the case, the presence of the appropriate ant species will also be a limiting factor.

Protection, status and ranks

The Half-moon Hairstreak was assessed as Endangered by COSEWIC in 2006, and listed as such on Schedule 1 of the federal Species at Risk Act (SARA) in 2007. Critical habitat for the species was identified under this Act in 2016. The Waterton Lakes population of Half-moon Hairstreak is only found in WLNP, and both the host plant species and its habitat are afforded protection under the Canada National Parks Act. In British Columbia, the species is identified as a species at risk under the provincial Forest and Range Practices Act and is listed as Identified Wildlife under the Identified Wildlife Management Strategy.

The Half-moon Hairstreak is ranked apparently secure (G4) globally, critically imperilled (N1) nationally, and S1 provincially in both British Columbia and Alberta. The larval host plants are not at risk. The Okanagan-Similkameen population has been recorded from private properties, private conservation land, provincial protected areas, federal property leased to a private ranch operator, and parcels of unprotected provincial land.

Technical summary – Okanagan-Similkameen population

Half-moon Hairstreak – Okanagan-Similkameen population

Porte-queue cendré - Population de l'Okanagan et de la Similkameen

Satyrium semiluna

Range of occurrence in Canada: British Columbia

Demographic information

Generation time:

1 year

Is there an [observed, inferred, or projected] continuing decline in number of mature individuals?

Inferred and projected continuing decline in mature individuals based on decline in habitat quality and quantity (see threat 7.3 Other ecosystem modifications)

Estimated percent of continuing decline in total number of mature individuals within [5 years or 2 generations]:

Unknown

[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over the last [10 years, or 3 generations]:

Unknown

[Projected or suspected] percent [reduction or increase] in total number of mature individuals over the next [10 years, or 3 generations]:

Unknown

[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over any [10 years, or 3 generations] period, over a time period including both the past and the future:

Unknown

Are the causes of the decline a. clearly reversible; b. understood; c. ceased?

1. No
2. Partially understood
3. No

Are there extreme fluctuations in number of mature individuals?

No

Extent and occupancy information

Estimated extent of occurrence (EOO):

578 km²

Index of area of occupancy (IAO) :

104 km²

Is the population “severely fragmented” that is, is >50% of its total area of occupancy in habitat patches that are (a) smaller than would be required to support a viable population, and (b) separated from other habitat patches by a distance larger than the species can be expected to disperse?

1. No
2. No

Number of “locations”^*(use plausible range to reflect uncertainty if appropriate):

± 6 based on differing land management practices at each of the 6 extant subpopulations.

Is there an [observed, inferred, or projected] decline in extent of occurrence?

Possible for habitat not within protected areas and, in general, for areas of potential sagebrush habitat.

Is there an [observed, inferred, or projected] decline in index of area of occupancy?

Possible for habitat not within protected areas and, in general, for areas of potential sagebrush habitat.

Is there an [observed, inferred, or projected] decline in number of subpopulations?

Possible for habitat not within protected areas and, in general, for areas of potential sagebrush habitat.

Is there an [observed, inferred, or projected] decline in number of “locations”^*?

Possible for habitat not within protected areas and in general for areas of potential sagebrush habitat.

Is there an [observed, inferred, or projected] decline in [area, extent and/or quality] of habitat?

Yes. Inferred and projected for habitat not within protected areas and, in general, for areas of potential sagebrush habitat.

Are there extreme fluctuations in number of subpopulations?

No

Are there extreme fluctuations in number of "locations"^*?

No

Are there extreme fluctuations in extent of occurrence?

No

Are there extreme fluctuations in index of area of occupancy?

No

^* See COSEWIC Definitions and Abbreviations website and IUCN for more information on this term.

Number of mature individuals (in each subpopulation)

Subpopulations (give plausible ranges):

Low number of specimens collected and observed, insufficient information to calculate mature individuals

Unknown

N mature individuals total:

Unknown

Quantitative analysis

Is the probability of extinction in the wild at least [20% within 20 years or 5 generations, or 10% within 100 years]?

Not applicable, insufficient data.

Threats (direct, from highest impact to least, as per IUCN Threats Calculator)

Was a threats calculator completed for this species? April 7, 2021. Threat impact: Medium.

7.1 Fire and fire suppression (wildfire only): High to low impact

1.1 Housing and urban areas: Low impact

2.1 Annual and perennial non-timber crops: Low impact

7.3 Other ecosystem modifications (fire suppression, invasive plants): Low impact

9.3 Agricultural and forestry effluents: Low impact

11.2 Droughts: Low impact

8.1 Invasive non-native/alien species/diseases (parasitic fly only): Unknown impact

2.3 Livestock farming and ranching: Unknown impact

What additional limiting factors are relevant?

• Small population size and genetic isolation
• Larval host plant specificity
• Natural parasites
• Vulnerability to extremes in precipitation and temperature
• Limited dispersal ability
• Mutualistic relationship with ants (unknown species)

Rescue effect (immigration from outside Canada)

Status of outside population(s) most likely to provide immigrants to Canada:

Species is apparently secure (N4) in the United States; and apparently secure (S4) in Washington State

Is immigration known or possible?

Not likely. Adult butterflies are small, unable to disperse long distances and remain localized. Nearest sites in USA >150 km

Would immigrants be adapted to survive in Canada?

Yes

Is there sufficient habitat for immigrants in Canada?

Yes

Are conditions deteriorating in Canada?⁺

Yes, see Threats.

Are conditions for the source (that is, outside) population deteriorating?⁺

Yes, see Rescue effect.

Is the Canadian population considered to be a sink?⁺

Unknown, but unlikely, dispersal distance too far.

Is rescue from outside populations likely?

Unknown, but not likely.

⁺ See Table 3 (Guidelines for modifying status assessment based on rescue effect).

Data sensitive species

Is this a data sensitive species?

No

Current status

COSEWIC status history: The species was considered a single unit and designated Endangered in April 2006. Split into two populations in December 2022. The Okanagan-Similkameen population was designated Threatened in December 2022.

Status and reasons for designation

Status: Threatened

Alpha-numeric: B1ab(iii)+2ab(iii)

Reasons for designation: The butterfly occurs at fewer than 10 disjunct sites in southern British Columbia at the northern extreme of the species’ range. Changes in fire regime and invasion by non-native plants are reducing habitat quality, and some sites are under pressure from development. Combining these threats could reduce population size in the near future.

Applicability of criteria

Criterion A (Decline in total number of mature individuals):

Not applicable. Insufficient data to reliably infer, project, or suspect population trends.

Criterion B (Small distribution range and decline or fluctuation):

Meets Threatened, B1ab(iii)+2ab(iii). EOO (578 km²) and IAO (104 km²) below thresholds for Endangered, inferred and projected decline in habitat quality, but occurs in >5 locations, so Threatened.

Criterion C (Small and declining number of mature individuals):

Not applicable. Insufficient data to determine number of mature individuals and/or continuing decline.

Criterion D (Very small or restricted population):

Not applicable. Number of mature individuals unknown and vulnerability to rapid and substantial population decline are unknown.

Criterion E (Quantitative analysis): Not applicable. Analysis not conducted.

Technical summary - Waterton Lakes population

Half-moon Hairstreak - Waterton Lakes population

Porte-queue cendré – Population des Lacs Waterton

Satyrium semiluna

Range of occurrence in Canada: Alberta

Demographic information

Generation time:

1 year

Is there an [observed, inferred, or projected] continuing decline in number of mature individuals?

Inferred and projected continuing decline in number of mature individuals based on decline in habitat quality due to the spread of non-native Spotted Knapweed and based on population surveys:

Estimated percent of continuing decline in total number of mature individuals within [5 years or 2 generations]:

Unknown

[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over the last [10 years, or 3 generations]:

Unknown

[Projected or suspected] percent [reduction or increase] in total number of mature individuals over the next [10 years, or 3 generations]:

Unknown

[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over any [10 years, or 3 generations] period, over a time period including both the past and the future:

Unknown

Are the causes of the decline a. clearly reversible; b. understood; c. ceased?

1. Partially reversible through the control of invasive plants and habitat restoration.
2. partially understood
3. no

Are there extreme fluctuations in number of mature individuals?

No

Extent and occupancy information

Estimated extent of occurrence (EOO):

16 km²

Actual 2.97 km² (ECCC 2014)

Index of area of occupancy (IAO):

16 km²

Is the population “severely fragmented” that is, is >50% of its total area of occupancy in habitat patches that are (a) smaller than would be required to support a viable population, and (b) separated from other habitat patches by a distance larger than the species can be expected to disperse?

1. No
2. No

Number of “locations”^* (use plausible range to reflect uncertainty if appropriate):

1, threat from invasive Spotted Knapweed

Is there an [observed, inferred, or projected] decline in extent of occurrence?

No, but only 1 site known

Is there an [observed, inferred, or projected] decline in index of area of occupancy?

No, but only 1 site known

Is there an [observed, inferred, or projected] decline in number of subpopulations?

No, but only 1 site known

Is there an [observed, inferred, or projected] decline in number of "locations"^*?

No, but only 1 site known

Is there an [observed, inferred, or projected] decline in [area, extent and/or quality] of habitat?

Yes. Observed, inferred, and projected decline in quality of habitat based on invasive Spotted Knapweed encroachment

Are there extreme fluctuations in number of subpopulations?

No

Are there extreme fluctuations in number of "locations"^*?

No

Are there extreme fluctuations in extent of occurrence?

No

Are there extreme fluctuations in index of area of occupancy?

No

^* See COSEWIC Definitions and Abbreviations website and IUCN for more information on this term.

Number of mature individuals (in each subpopulation)

Subpopulations (give plausible ranges):

Low number of specimens collected and observed, insufficient information to calculate mature individuals

Unknown

N mature individuals total:

Unknown

Quantitative analysis

Is the probability of extinction in the wild at least [20% within 20 years or 5 generations, or 10% within 100 years]?

Not applicable, insufficient data.

Threats (direct, from highest impact to least, as per IUCN Threats Calculator)

Was a threats calculator completed for this species? April 7, 2021. Overall threat impact is Medium.

7.1 Fire and fire suppression (wildfire only): Medium impact

7.3 Other ecosystem modifications (invasive plants): Medium impact

11.2 Droughts: Low impact

11.4 Storms and flooding: Low impact

8.1 Invasive non-native/alien species/diseases: Unknown impact

8.2 Problematic native species/diseases: Unknown impact

What additional limiting factors are relevant?

• Small population size and genetic isolation
• Larval host plant specificity
• Natural parasites
• Vulnerability to weather patterns
• Dispersal ability
• Mutualistic relationship with ants (unknown species)

Rescue effect (immigration from outside Canada)

Status of outside population(s) most likely to provide immigrants to Canada:

Species is apparently secure: (N4) in the United States and (S4) in Montana. Likely a different DU.

Is immigration known or possible?

Not possible, separate DU

Would immigrants be adapted to survive in Canada?

Not applicable

Is there sufficient habitat for immigrants in Canada?

Yes

Are conditions deteriorating in Canada?⁺

Yes, see Threats.

Are conditions for the source (that is, outside) population deteriorating?⁺

Yes, see Rescue effect.

Is the Canadian population considered to be a sink?⁺

No

Is rescue from outside populations likely?

No

⁺ See Table 3 (Guidelines for modifying status assessment based on rescue effect).

Data sensitive species

Is this a data sensitive species?

No

Current status

COSEWIC status history: The species was considered a single unit and designated Endangered in April 2006. Split into two populations in December 2022. The Waterton Lakes population was designated Endangered in December 2022.

Status and reasons for designation

Status: Endangered

Alpha-numeric: B1ab(iii)+2ab(iii)

Reasons for designation: The butterfly is restricted to one small site in Waterton Lakes National Park in southern Alberta at the northern extreme of the species’ range and distant from any other sites. Population size is unknown, but very small, and has likely declined in the past as a result of habitat loss. An invasive plant, Spotted Knapweed, is an ongoing threat that reduces habitat quality and availability of nectar plants.

Applicability of criteria

Criterion A (Decline in total number of mature individuals):

Insufficient data to reliably infer, project, or suspect population trends.

Criterion B (Small distribution range and decline or fluctuation):

Meets Endangered, B1ab(iii)+2ab(iii). EOO (16 km²) and IAO (16 km²) well below threshold for Endangered, occurs in <5 locations and there is an inferred and projected continuing decline in habitat quality.

Criterion C (Small and declining number of mature individuals):

Not applicable. Insufficient data to determine number of mature individuals and/or continuing decline.

Criterion D (Very small or restricted population):

Meets Threatened, D2. Restricted to one location and prone to substantial decline from effects of human activities or stochastic activities within 1–2 generations.

Criterion E (Quantitative analysis): Not applicable. Analysis not conducted.

Preface

The Half-moon Hairstreak was assessed as Endangered by COSEWIC in 2006 and listed as such on Schedule 1 of the federal Species at Risk Act (SARA) in December 2007. Critical habitat was identified under this Act in 2016. In Alberta (AB), the Half-moon Hairstreak is found in Waterton Lakes National Park (WLNP), and individuals of the host plant species and its habitat are afforded protection under the Canada National Parks Act. In British Columbia (BC), the species is identified as a species at risk under the provincial Forest and Range Practices Act and is listed as Identified Wildlife under the Identified Wildlife Management Strategy.

Since the first COSEWIC status assessment, knowledge regarding the spatial connectivity of subpopulations has improved. There are seven subpopulations in Canada (one in AB and six in BC). This differs from the first COSEWIC assessment, which lists eight subpopulations. During searches conducted in the 2007-2021 period, additional sites were found between two of the subpopulations, meaning it is now considered one subpopulation. Four of the six known subpopulations in BC are extant and are found primarily on provincial or federal lands. Two of the six subpopulations occur entirely on private lands where surveys have not been conducted for approximately 20 years. Their subpopulation status is unconfirmed, but they are likely extant because the habitat still appears to be suitable. Additional inventory work has been completed in other sagebrush habitats in the province, but no additional subpopulations have been found. Surveys at WLNP confirm that the population is extant, and no additional occurrences have been found in similar habitat nearby.

Half-moon Hairstreak was assessed as one Designatable Unit (DU) in the first COSEWIC status report (2006). Additional information obtained since the first COSEWIC report suggests differences in morphology, behaviour, and habitat use between British Columbia and Alberta. In addition, recent work demonstrates significant genetic differences (see Designatable units). Therefore, the assessment is based on a two DU structure: the Okanagan-Similkameen population in BC, and the Waterton Lakes population in AB.

COSEWIC history

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions (2022)

Wildlife Species

A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)

A wildlife species that no longer exists.

Extirpated (XT)

A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)

A wildlife species facing imminent extirpation or extinction.

Threatened (T)

A wildlife species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)*

A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR)**

A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD)***

A category that applies when the available information is insufficient (a) to resolve a species’ eligibility for assessment or (b) to permit an assessment of the species’ risk of extinction.

* Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.

** Formerly described as “Not In Any Category”, or “No Designation Required.”

*** Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994. Definition of the (DD) category revised in 2006.

The Canadian Wildlife Service, Environment and Climate Change Canada, provides full administrative and financial support to the COSEWIC Secretariat.

Wildlife species description and significance

Name and classification

Classification:

Phylum: Arthropoda

Class: Insecta

Order: Lepidoptera

Family: Lycaenidae

Genus: Satyrium

Species: Satyrium semiluna Klots 1930

Synonyms: Satyrium fuliginosum (W.H. Edwards 1861); Satyrium fuliginosa semiluna

Type locality: Half-Moon Ranch, Jackson Hole, Teton County, Wyoming (Klots 1930).

English Common Names: Half-moon Hairstreak, Sooty Hairstreak, Sagebrush Sooty Hairstreak, Semiluna Hairstreak

French Common Name: Porte-queue demi-lune

Indigenous Names: none

Taxonomic background and similarities

The Half-moon Hairstreak (Satyrium semiluna Klots) was formerly a subspecies of Sooty Hairstreak (as Satyrium fuliginosa semiluna). However, recent taxonomic work (see Warren 2005) resulted in the separation of S. fuliginosa into two species, with S. semiluna elevated to species status.

Prior to Warren (2005), Layberry et al. (1998) called all Canadian material Satyrium fuliginosum. Later, Guppy and Shepard (2001) referred to the Okanagan-Similkameen hairstreaks as S. fuliginosum semiluna. Pyle (2002) also quotes A. Warren [BC subpopulations] as “probably undescribed” subspecies. The BC population may be a separate undescribed subspecies of S. semiluna from those in Alberta (AB) (as outlined by Kondla 2003b). MacDonald and Dupuis (pers. comm. 2022) suggest that the Waterton Lakes population could warrant description as a subspecies. However, there are no formal taxonomic descriptions. Regardless of formal subspecies descriptions, there is evidence to support two designatable units (DUs) for Half-moon Hairstreak based on morphology, behaviour, ecology, and genetic structure each supports discreteness and significance (see Designatable units).

Morphological description

Half-moon Hairstreak develops through complete metamorphosis (see Biology). It has an annual life cycle with four distinct developmental life stages (egg, larva [four instars], pupa, and adult).

Adults

The Half-moon Hairstreak is a small butterfly with a 2.5 to 3.4 cm wingspan. The dorsal wing surfaces have a uniform brownish-black sooty colouration (Figures 1 and 2) and are fringed with scales varying in colour from grey to tan to white. Adults lack the small tail-like extensions on their hindwings that are found in many other hairstreaks. Sexes differ slightly, with females being larger and paler than males. For further descriptions, see Warren (2005), James and Nunnallee (2011), and ECCC (2016).

There are morphological differences between the BC (Figures 1 and 3) and AB (Figures 2 and 4) populations, which provide supporting evidence for two designatable units (see Designatable units for full discussion).

Figure 1. Dorsal wing surfaces of Half-moon Hairstreak collected in British Columbia. Anarchist Mountain, near Osoyoos, BC (collected June 21, 1975, by J.L. Gordon) and housed at the University of British Columbia Spencer Entomological Museum. Photo by J. Heron

Figure 2. Ventral wing surfaces of Half-moon Hairstreak. The discal spot on this specimen is not typical; it is usually darker in other specimens (see arrow). Specimen from Anarchist Mountain, near Osoyoos, BC (collected June 21, 1975, by J.L. Gordon) and housed at the University of British Columbia Spencer Entomological Museum. Photo by J. Heron.

Figure 3. Ventral wing surfaces of a male Half-moon Hairstreak, collected from Waterton Lakes National Park, Alberta. Photo by N. Kondla.

Figure 4. Ventral wing surfaces of a male Half-moon Hairstreak, collected from Waterton Lakes National Park, Alberta. Photo by N. Kondla.

Eggs

Half-moon Hairstreak eggs are greenish white to golden brown (Scott 1986 a,b; 1992) with intersecting ridges “covered with a thick shiny layer of transparent cement” (James and Nunnallee 2011). There is one observation of an egg, from White Lake (#3^{Footnote 1}; St. John pers. comm. 2020).

Larvae

Half-moon Hairstreak larvae have a brown head and a light green body with white chevrons on the lateral surface (Scott 1986 a,b; 1992; Ballmer and Pratt 1988; James and Nunnallee 2011). Larvae observed in WLNP (#1) were light brown, small (< 1 cm length) and were at the base of a lupine (Sissons pers. comm. 2021; Glasier pers. comm. 2022). Larvae have not been observed in BC.

Pupae

Half-moon Hairstreak pupae are brown and shiny, with a row of obscure reddish spots. Pupae are covered in numerous inconspicuous blonde and stubbly setae (hairs) (James and Nunnallee 2011). Pupae have been observed in the Waterton Lakes population (Sissons pers. comm. 2021)

Population spatial structure and variability

Population spatial structure and variability studies in both the Okanagan-Similkameen and Waterton Lakes populations are limited to abundance observations across a few dates. The Okanagan-Similkameen records indicate that the butterfly is restricted to sagebrush communities and may be composed of subpopulations that are connected through dispersal at a local scale (that is, patches of habitat that form a metapopulation structure, termed a subpopulation^{Footnote 2}) but are isolated at a regional scale (that is, the subpopulations do not intermix). The Waterton Lakes population is restricted to the Blakiston Fan, and there are no studies on intrapopulation structure and variability. Gene flow between the Okanagan-Similkameen and Waterton Lakes populations is unlikely because of the extensive geographical separation (> 400 km) and ecological barriers. This has been corroborated by MacDonald and Dupuis (2022). More detail is provided under Designatable units. There are no records of Half-moon Hairstreak in the northern United States between the two Canadian populations. It is unclear whether there is suitable interconnecting habitat in the United States.

Designatable units

In the previous assessment (COSEWIC 2006), Half-moon Hairstreak was considered one Designatable Unit (DU). COSEWIC (2020) defines designatable units (DUs) based on discreteness and evolutionary significance. Populations are discrete if there is little transmission of heritable information from other populations, and evolutionarily significant if they have distinct adaptive traits or an evolutionary history not found in other Canadian populations. Based on these criteria and differences in morphology and habitat use along with more recently obtained genetic structure data, the geographically separated BC and AB populations fit a two DU structure: DU 1 - Okanagan-Similkameen population in BC, and DU 2 - Waterton Lakes population in AB.

Discreteness is recognized based on heritable traits (D1) or natural geographic disjunction (D2).

D1. Heritable traits

Evidence of genetic distinctiveness includes differences in morphology and life history traits. All Canadian Half-moon Hairstreak subpopulations are currently described as one subspecies (nominate^{Footnote 3} subspecies, Satyrium semiluna semiluna). However, according to Kondla (2003b; pers. comm. 2019) Okanagan-Similkameen males are measurably and consistently larger than those from Waterton Lakes (Figures 2 and 4), and the overall colouration of Waterton Lakes specimens is consistently lighter grey. Further, Waterton Lake specimens do not have androconial patches on the wings. Because the androconial patches are involved in chemical communication between males and females, this suggests there may be differences in pheromone communication during mating. These morphological and behavioural differences may support erecting two subspecies (Guppy pers. comm. 2019; Kondla pers. comm. 2019).

There is also evidence of behavioural differences between the Okanagan-Similkameen and Waterton Lakes populations. Sagebrush shrubs in provide mating and roosting sites for the Okanagan-Similkameen population. In Waterton Lakes, and more specifically Blakiston Fan, there are no similar shrubs. There, butterflies use Wolf Willow (Elaeagnus commutata) for roosting and perching. Wolf Willow occurs in sparse to dense patches in a small portion of the Blakiston Fan (Sissons pers. comm 2021). Kondla (pers. comm. 2019) has noted differences in flight behaviour between the Waterton Lakes and Okanagan-Similkameen populations, which may be due to this structural habitat difference. Whereas in BC, the butterflies often fly at shrub height (for example, 1 to 2 m above the ground), in Blakiston Fan, they keep low to the ground (< 60 cm). Typically, they land on low vegetation and occasionally on bare soil rather than on shrubs (Kondla pers. comm. 2019).

Recent work on the genetic structure of Half-moon Hairstreak from the Okanagan-Similkameen, Waterton Lakes and Montana populations involving collaboration between the University of Alberta, Parks Canada, the Calgary Zoo, and other experts (Sperling pers. comm. 2022) shows significant differences in genetic make-up between Okanagan-Similkameen and Waterton Lakes populations based on whole genome sequences. This supports genetic distinctiveness associate with behavioural differences. More details on this work are provided below under Significance.

D2. Natural geographic disjunction

The two closest subpopulations of Half-moon Hairstreak in Canada are naturally disjunct. The minimum straight-line distance between the Okanagan-Similkameen (#2 Anarchist Mountain) and AB (#1 Waterton Lakes) subpopulations is approximately 400 km. Most of the land between the two areas is unsuitable habitat, especially the Rocky Mountains.

The closest Half-moon Hairstreak record from south of the Okanagan‑Similkameen population is a specimen collected in sagebrush grassland in the Sinlahekin Wildlife Area in Washington State, about 30 to 40 km south of the international border (Kondla pers. comm. 2021). However, there are no records from the past 10 years. The most recent record in nearby Washington is from Sunnyslope (19 June 2019, iNaturalist 2020), which is approximately 177 km south of the closest known record in BC (#3). The habitat occupied in Washington appears to be similar to that in BC (that is, sagebrush shrub-steppe, see Habitat).

The closest known Half-moon Hairstreak records south of Waterton Lakes are in southwestern Montana (at Big Horn, Carbon, Gallatin, Meagher, Sweet Grass, and Wheatland (Kohler 1980; Stanford and Opler 1993). One record on iNaturalist (2020) is from Carbon County, Montana, 560 km from Waterton Lakes (#1). There is a closer record of Half-moon Hairstreak, which was collected 460 km south of Waterton Lakes in Lemhi County, Idaho (iNaturalist 2020). The Lemhi County observation appears to be in habitat similar to that of the Okanagan-Similkameen populations (that is, sagebrush shrub-steppe, see Habitat). There are no historical Half-moon Hairstreak observations that were collected in areas between the Idaho, Montana, British Columbia, and Alberta records. The Waterton Lakes population appears to be disjunct not only from the Okanagan-Similkameen population but also from occurrences in Montana and Idaho. The genetic structure described by MacDonald and Dupuis (pers. comm. 2022) provides evidence for this natural disjunction.

Evolutionary significance is based on evidence or strong inference that DUs have followed independent evolutionary trajectories over a significant period (S1; COSEWIC 2020), or evidence or strong inference that they possess adaptive, heritable traits that cannot be practically reconstituted if lost (S2).

MacDonald and Dupuis (pers comm. 2022) provided a summary of work done on the genetic structure of Half-moon Hairstreak from three geographic areas: Okanagan-Similkameen, Waterton Lakes and southern Montana. They concluded that Okanagan-Similkameen and Waterton Lakes are distinct. This lengthy quote from MacDonald and Dupuis (pers. Comm. 2022) provides some background on methods, results, and conclusions.

“We have assembled a chromosome-level reference genome for Satyrium semiluna, mapping the identity and location of 1.25 billion base pairs and organizing them into 31 chromosomes. We have also sequenced the entire genomes of 15 individuals (mean coverage = 16x) collected from Waterton National Park, Alberta (n = 4), southern British Columbia (BC) (n = 7), and southern Montana (n = 4). Using these sequence data, we were able to identify over a million Single Nucleotide Polymorphisms (SNPs) among the 15 individuals. After stringent filtering, ~100,000 SNPs were used to assess population structure. Population divergence between the three locations is substantial. Fst values between Alberta and BC, Alberta and Montana, and BC and Montana are 0.402, 0.282, and 0.307, respectively.

Our results indicate that the isolated Alberta population is more closely related to other populations east of the Continental Divide than to populations in BC that are geographically closer. Population clustering analyses (using the program structure) indicate that there is no admixture among Alberta, BC, and Montana populations. Based on the substantial genomic divergence between Alberta and BC populations and the lack of admixture, these data support the recognition of Canadian populations as two units (Alberta and BC).

More sampling is required between British Columbia and Montana to determine whether each represents a distinct evolutionary unit or whether they are connected by a cline of genomic divergence. This will help contextualize the uniqueness of the Alberta population, which may warrant recognition as a distinct subspecies.”

Recognition by experts as a potential separate subspecies and the population genetic structure both support Waterton Lakes and Okanagan-Similkameen as units that would not be able to be reconstituted if lost in Canada.

Special significance

Hairstreak (Satyrium spp.) butterflies are of interest to lepidopterists because of their taxonomic and systematic complexity, their rarity, and their association with at-risk plant communities. The sagebrush ecological communities of the southern Okanagan and lower Similkameen valleys are a hotspot for rare and at-risk invertebrates in Canada (BC CDC 2021). Half-moon Hairstreak can be considered a focal species representing the sensitivity and uniqueness of these habitats in Canada.

Waterton Lakes National Park supports a unique assemblage of species within Canada that are at the northernmost extent of their global range, and Half-moon Hairstreak is a focal species.

Distribution

Global range

Globally, the Half-moon Hairstreak occurs in western North America from south-central BC, south through eastern Washington and Oregon, Idaho, northeastern California and northern Nevada, to Colorado, Montana and the northeasternmost extreme of its range, in WLNP, AB (Figure 5) (James and Nunnallee 2011; BC CDC 2021). Less than 1% of the global range of Half-moon Hairstreak is in Canada.

Figure 5. Global range of Half-moon Hairstreak. Map created by Greg Amos (B.C. Ministry of Environment and Climate Change Strategy 2021).

Canadian range

In Canada, Half-moon Hairstreak occurs as two designatable units (see Designatable units): the Okanagan-Similkameen population^{Footnote 4} and the Waterton Lakes population (Figure 6).

Figure 6. Canadian range of Half-moon Hairstreak, showing both the Okanagan-Similkameen population in British Columbia and the Waterton Lakes population in Alberta. Map created by Greg Amos (B.C. Ministry of Environment and Climate Change Strategy 2021).

The Okanagan-Similkameen population occurs in the southern Okanagan and Similkameen valleys (Figure 7) in British Columbia. There are six subpopulations^{Footnote 5} and all are considered extant (Table 1, Figure 7). The northernmost subpopulation is in the White Lake basin (#7), southwest of Penticton, and the southernmost location is along the United States border about 6 km west of Osoyoos in the South Okanagan Grasslands Protected Area (#4).

The Waterton Lakes population is in extreme southwestern Alberta and located entirely within the Blakiston Fan in WLNP (Table 1, Figure 8).

The absence of Half-moon Hairstreak from other sites where the host plants occur suggests that there are other, unknown factors that restrict the butterfly to these two areas in Canada (see Limiting factors).

Figure 7. Half-moon Hairstreak (Satyrium semiluna) Okanagan-Similkameen population in British Columbia (#2–7). See Tables 1 and 2 for associated information. Map created by Greg Amos (B.C. Ministry of Environment and Climate Change Strategy 2021).

Figure 7a. Half-moon Hairstreak (Satyrium semiluna) Okanagan-Similkameen population in British Columbia (#2 to 7) Index of Area of Occupancy (IAO; 2 km x 2 km grid squares) over known occurrences. The IAO is calculated from 26 grid squares as 104 km². Map created by Alain Filion (COSEWIC Secretariat). [Editorial note: This figure has been removed to protect precise location information. Please contact the COSEWIC Secretariat if you require this information.]

Figure 8. Half-moon Hairstreak (Satyrium semiluna) Waterton Lakes population showing all of Blakiston Fan within Waterton Lakes National Park (#1), Alberta. Map created by Greg Amos (B.C. Ministry of Environment and Climate Change Strategy 2021).

Figure 8a. Half-moon Hairstreak (Satyrium semiluna) Waterton Lakes population Index of Area of Occupancy (IAO; 2 km x 2 km grid square over known records) within Waterton Lakes National Park (#1), Alberta. The IAO is calculated from four grid squares and is 16 km². Map created by Alain Filion (COSEWIC Secretariat). [Editorial note: This figure has been removed to protect precise location information. Please contact the COSEWIC Secretariat if you require this information.]

Extent of occurrence and area of occupancy

The EOO for the Okanagan-Similkameen population is 578 km² and the IAO, 104 km² (Table 1; Figure 7a).

The EOO for the Waterton Lakes population is 2.97 km² and the IAO, 16 km² (Table 1; Figure 8a). According to a COSEWIC convention, when the EOO is less than the IAO, the EOO must be increased so that it is equal to the IAO. Therefore, the EOO for the Waterton Lakes population is 16 km². The EOO and the IAO reported here have been updated based on new and more accurate mapping (from BC CDC 2021). Any changes from the previous status report ( COSEWIC 2006) are not based on habitat loss or declines.

Search effort

Half-moon Hairstreak surveys have been conducted by wandering transects through potential habitat, stopping periodically to gently shake or knock herbaceous and shrubby vegetation and flush out resting butterflies. Half-moon Hairstreaks tend to sit on nectar plants and shrubbery, and this is why gently tapping shrubbery is an effective method. Wandering transects allow the surveyor to change course depending on the host plant and nectar resources encountered (for example, places where adult butterflies congregate). This is an effective method of determining butterfly presence when little information is available on the species’ preferred microhabitats and its roosting, mating, or resting sites (Longcore et al. 2010). Surveys typically do not target eggs, larvae, or pupae because these life stages are cryptic and difficult to locate among host plants (see Life Cycle).

Half-moon Hairstreaks may be overlooked due to their non-descript grey colouration, small size, and low abundance. However, butterfly enthusiasts are keen to seek them out and with the rise in popularity of online citizen science forums such as BugGuide® and iNaturalist®, more observers are contributing observations. There are no Half-moon Hairstreak records for either DU posted on BugGuide® (as of January 28, 2022). There are 30 records posted on iNaturalist^® in Canada (as of October 3, 2022): 1 from Anarchist Mountain (#3), 7 from South Okanagan Grasslands Protected Area (#4), 5 from east of Mount Kobau (#5), 6 from White Lake (#7) and 10 from Waterton Lakes (#1) (as of January 27, 2022), all of them corroborated and reviewed by Canadian experts.

Surveys for Half-moon Hairstreak in the past 10 years (Table 2) have focused on surveying potential habitat, recording the species’ abundance, and documenting habitat and natural history information. Data were assembled from numerous sources (see Collections Examined and Table 2).

Okanagan-Similkameen population history and surveys: Half-moon Hairstreak museum specimens, inventory information, and photographic records in Canada date from 1895 to 2021 (Table 1). The earliest Canadian records consist of ones labelled ‘Osoyoos’ in 1895 and three specimens collected between 1898 and 1901 at an unknown site in BC. Subsequently, there were a few collections from the vicinity of Keremeos in 1923 and from Anarchist Mountain in 1975, 1976, 1979, 1985, and 1990; and there is one sight record from Richter Pass in 2002 (COSEWIC 2006). The most recent records consist of photographs posted to iNaturalist^© Mount Kobau, east of (#5) (2020), White Lake (#7) (2021), and South Okanagan Grasslands Protected Area (#4) (2021) (Table 1).

In preparation for the first COSEWIC status report (2006), field surveys were carried out in 2003 to confirm some past records and locate additional sites. This work resulted in the documentation of new sites in the vicinity of Kilpoola Lake (#4), White Lake (#7), and Mt. Kobau (#5), as well as the confirmation of the species’ presence at Richter Pass (#5) and Anarchist Mountain (#3). An additional site near Keremeos Columns Provincial Park (#6) was reported in 2003 (Fenneman pers. comm. 2003 as cited in COSEWIC 2006).

A minimum of 1,504 hours of search effort has been completed since 2010 (Table 2). No additional subpopulations have been recorded since the first COSEWIC assessment (2006), although the area of occupancy of the butterfly has expanded (for example, there are more sites; the species forms a metapopulation where some sites are occupied in some years but not others). The range and spatial area of occupancy of the Half-moon Hairstreak in BC is well-defined (for example, #4, 5, 6, 7).

There may be additional sites that support Half-moon Hairstreaks in grasslands in the east Kootenay region between the Okanagan-Similkameen and Waterton Lakes populations. Priority areas in British Columbia include the dry grasslands from Rock Creek to Grand Forks and portions of the southern Rocky Mountain Trench. Some search effort has taken place within Grand Forks and the Kootenay region (see Table 2) but no observations were made.

Waterton Lakes population history and surveys in Alberta: “… there is an old record from Waterton Lakes in Alberta” is the extent of the reporting on the Waterton Lakes population in The Butterflies of Canada (Layberry et al. 1998) (as Sooty Hairstreak). iNaturalist includes 4 observations from 2020 to 2022.

In preparation for the first COSEWIC status report (2006), Kondla (2003a, 2004) searched for Half-moon Hairstreak in habitats with lupines at low to high elevations outside of the Blakiston Fan; only three individuals were observed on hummocky moraine fan habitat (Kondla 2003a, 2004). These three individuals were observed under very windy conditions and only in 2003. Surveys in this same habitat in 2004 under calm conditions (that is, no wind) failed to record additional hairstreaks. Therefore it is possible that the three individuals seen in 2003 had blown in from their normal habitat.

There has been some search effort in and near WLNP since the first COSEWIC status report (2006). Additional surveys conducted in 2009 in other habitats within WLNP did not reveal new occurrences (Kondla 2009; Table 3). Surveys undertaken by Sissons (pers. comm 2020–2021) between 2017 and 2021 confirmed the presence of Half-moon Hairstreak at Blakiston Fan. Future surveys could be conducted on the sage slopes in the South Castle River valley in AB, which may contain suitable habitat for the species.

Larval searches have continued within the Blakiston Fan. Parks Canada staff reported that they were most successful at finding larvae when they focused on identifying ant activity below a lupine and then checked for small larvae in the duff layer below the plant. Larvae were observed starting in mid-May and were confirmed to be Half-moon Hairstreak larvae in 2021 (see Morphological description for more details) (Sissons pers. comm. 2021).

There is no specific Aboriginal Traditional Knowledge available on the distribution or abundance of Half-moon Hairstreak for either DU. However, Half-moon Hairstreak is part of ecosystems that are important to Indigenous people who recognize the interconnectedness of all species.

Habitat

Habitat requirements

Okanagan-Similkameen population

Half-moon Hairstreak habitat includes the Big Sagebrush / Bluebunch Wheatgrass ecological community (Figure 9), at an elevation of 600 to 1,000 m above sea level (asl) and with reduced relief in comparison to surrounding steeper areas.

Figure 9. Habitat of Half-moon Hairstreak (Satyrium semiluna) at White Lake (#7 on Figure 7 concerning the Okanagan-Similkameen population) (west of Okanagan Falls), June 17, 2010. The most recent Half-moon Hairstreak (Satyrium semiluna) observation at White Lake was made on June 17, 2020 (Table 1). Photo by J. Heron.

The larval host plants for Half-moon Hairstreak are lupines (Lupinus spp.) although the specific host plants in BC are speculative: Silky Lupine, (Lupinus sericeus) and Sulphur Lupine (Lupinus sulphureus) are at known sites (St. John pers. comm. 2019). Elsewhere within the global range of Half-moon Hairstreak, Spurred Lupine (Lupinus arbustus) is a known larval host plant. However, this lupine species is likely not a host plant for either Canadian DU because it does not occur in BC or AB (BC CDC 2021).

Additional flowering nectar plants at Half-moon Hairstreak sites include Common Yarrow (Achillea millefolium), Umbrella-plant (Eriogonum heracleoides), Missouri Goldenrod (Solidago missouriensis) (COSEWIC 2006; Knopp et al. 2008), and Grey Horsebrush (Tetradymia canescens). Nectar plants are likely chosen opportunistically (St. John pers. comm. 2019).

Additional common plants in this ecological community include Big Sagebrush, Prairie Junegrass, Bluebunch Wheatgrass, Idaho Fescue (Festuca idahoensis), and Pinegrass (Calamagrostis rubescens).

Waterton Lakes population

Half-moon Hairstreak habitat is found within the Blakiston Creek alluvial fan (Figure 10) in the Foothills Parkland Natural Subregion as described in the document Natural Regions and Subregions of Alberta (2006) and Blakiston Ecosection of WLNP (Parks Canada Agency 2003).

Figure 10. Habitat of Half-moon Hairstreak (Satyrium semiluna), Blakiston Fan, Waterton Lakes National Park, June 20, 2019. Photo by Jennifer Heron.

The Blakiston Ecosection (BL) is composed of dry grassland (BL1 and BL2 dry grassland ecosites) and aspen parkland (BL3 and BL4 ecosites) (Achuff et al. 2002). The soils were formed on rapidly to moderately well-drained, coarse-textured fluvial landforms (Achuff et al. 2002). The vegetation communities found in all four ecosites are the H25 type, Oatgrass-Rough Fescue-June Grass. This is the most common and widespread vegetation type in the grasslands (Achuff et al. 2002) and it includes a dominant component of bunchgrasses. This vegetation type is found on mesic gentle slopes with a variety of aspects at elevations ranging from 1,280 to 1,560 m asl. The second vegetation type found in these ecosites is the H27 type, Bluebunch Wheatgrass-Rough Fescue. Whereas oatgrasses are dominant in the H25 vegetation type, this type of plant is not found in the H27 vegetation community. This vegetation type is found on subxeric to mesic, gentle to steep south-facing slopes, at elevations between 1,300 and 1,700 m asl (Achuff et al. 2002).

The larval host plants found in both vegetation types consist of Silvery lupine (Lupinus argenteus) and Silky Lupine, with Silvery Lupine appearing to be preferred (James Glasier pers. comm. 2022). The percent cover of Silvery Lupine ranged from 0% to 10% in localized areas of the fan (Tannas 2014), while the cover of Silky Lupine ranged from < 0.5% to 15% across the Blakiston fan (Achuff et al. 2002).

Silvery Lupine cover was much lower in the 2000s than in the1990s (2008 = 0.2% and 2013 = 0.5%) and restricted to core hairstreak habitat (Tannas 2014). Surveys in the mid-1990s estimated Silky Lupine cover to be up to 15% in general vegetation plots (Achuff et al. 2002) and up to 65% (range 0–65%) in plots where hairstreak butterflies were present (Kondla 2004). Tannas (2014) recorded Silky Lupine across all areas of hairstreak habitat, with cover averaging 9.1% in 2008 and 8.6% in 2013.

Yellow Buckwheat (Eriogonum flavum) and Missouri Goldenrod are prominent flowering nectar plants (Kondla 2004).

Habitat attributes applicable to both DUs

Mating

Larval and nectar host plants may provide mating sites for Half-moon Hairstreak. Mating pairs have been observed on flowers of Yellow Buckwheat, Missouri Goldenrod (#2–7; St. John pers. obs. 2008), Prairie Sagewort (Artemisia frigida) and various species of lupines (#2–7). Half-moon Hairstreak has been observed mating on Big Sagebrush (#2–7; Knopp pers. comm. 2020), a shrub that may be important for male perching (COSEWIC 2006). In WLNP (#1), mating pairs have been observed on goldenrod (Solidago spp.), buckwheat (Eriogonum spp.), Prairie Sagewort, and lupines (Kondla 2009). Adults perch on non-native Spotted Knapweed (Centaurea stoebe, formerly C. maculosa and tetraploid form known as C. biebersteinii) (#1); however, no mating or feeding was observed (Sissons pers. comm., 2021).

Ants (Family Formicidae)

Ants play a role in the presence of Half-moon Hairstreak, as ants were observed in close association with lupine plants in locations where the Half-moon Hairstreak occurs at the White Lake (#7) (St. John pers. comm. 2008 as cited in ECCC 2016). In WLNP, Glasier (2022) has observed Lasius americanus and three species of wood ants (Formica argentata, F. neogagates and F. obscuripes) protecting and grooming Half-moon Hairstreak caterpillars (see Interspecific interactions).

Habitat trends

Okanagan-Similkameen population

Historical trends in habitat loss continue as a result of strong pressure to develop undesignated provincial land and private ranchland for more intensive use (for example, housing, commercial development, and more intensive agricultural use). These trends will continue, particularly on undesignated provincial land that can be sold to the private sector for further development.

The conversion of rangelands to orchards and the conversion of orchards and other fruit crops to vineyards is prevalent throughout the region. Vineyard agriculture typically involves more intensive use of land than orchards, with fewer natural plants and natural patches of habitat and more intensive pesticide applications. The rich, sandy, and well-drained soils that support the grassland ecological communities of the Okanagan and Similkameen valleys are considered an indicator for high grape crop production and continue to be specifically targeted for development by the wine industry (COSEWIC 2012; ECCC 2016). Sometimes, pockets of natural intact habitat remain within these developed agricultural areas and small populations of butterflies can persist. However, surveys conducted over a four-year period on private farms and in vineyards, and other agricultural areas within the Okanagan and Similkameen valleys did not record any Half-moon Hairstreak (Table 2).

In southern BC, the distribution and abundance of invasive plant species have increased since European settlement (Environment Canada 1999; CCIS 2021). Invasive plants alter natural habitats, compete with native plant species for nutrients, space, and water, degrade resources for wildlife, and alter fire regimes (CCIS 2021). Invasive plant species are a concern in the Okanagan-Similkameen region, with at least 40 plant species being tracked by the Okanagan and Similkameen Invasive Species Society (2021). Non-native plant invasions are second to habitat loss in terms of the threat they pose to Okanagan Valley grasslands (Cannings et al. 1998). Habitat degradation trends in this region are ongoing from the long-term cumulative ecosystem modification from invasive plants at all subpopulations (#2–7).

Historically, livestock grazing has affected all subpopulations (#2–7) (COSEWIC 2006). In the past 10 years, grazing pressure has decreased in some portions of the South Okanagan Grasslands area (#4) as a result of the establishment of the Sage and Sparrow grasslands protected area by the Nature Conservancy of Canada. In other portions of the protected area, grazing has ceased entirely because these locations cannot be accessed through private land. It is not known whether grazing occurs at Anarchist Mountain (#3); however, some grazing likely occurs at Veronica Lake (#2). It appears that Half-moon Hairstreak can persist in areas with low grazing regimes, likely because the larval host plants (that is, lupines) are not consumed by livestock. No formal studies have been completed.

Lupines are early successional plants (USDA-USFS 2021) that are negatively impacted by fire suppression. Fire suppression leads to tree encroachment into open habitats such as those used by Half-moon Hairstreak. The alteration to fire regimes that is associated with the elimination of low- and medium-severity fires can make ecosystems vulnerable to high-severity fires, even beyond the levels of severity historically experienced in an area (Brookes et al. 2021).

Historical wildfires have affected various areas including Anarchist Mountain (#3), which burned in 2003 (COSEWIC 2006). In 2014, wildfire burned a 20-ha area at White Lake (#7) including most of the habitat where Half-moon Hairstreak was known to occur (Dyer pers. comm. 2019; Bunge pers. comm. 2020). Surveys in 2019 confirmed that the subpopulation is still present at this site (Heron pers. comm. 2021), and incidental observations of Half-moon Hairstreak were made here in 2021 (iNaturalist 2022). In 2015, the 5,202-ha Testalinden Creek wildfire included habitat occupied by Half-moon Hairstreak east of Mount Kobau (#5) (Province of British Columbia 2022). Surveys conducted in 2020 confirmed that the subpopulation is still present at this site (Bunge pers. comm. 2020).

Taking into account the slow and gradual decline in habitat quality associated with ecosystem modifications (for example, fire suppression, invasive native/non-native species ingrowth, adverse effect of wildfire smoke pollution on host plant and nectar plant growth), there is an inferred and projected decline in extent of occurrence and index of area of occupancy.

Waterton Lakes population

Waterton Lakes National Park was established in 1895. The wide open grasslands of the Blakiston Fan enabled temporary human encampments, staging areas, and infrastructure development. Grazing of cattle and horses was permitted in the national park starting in 1914, and for most of the following 40 years, the area was subject to various levels of grazing. In 1947, livestock grazing in the park was stopped due to the public outcry over habitat degradation caused by the presence of too many cattle (Parks Canada Agency 2016).

Although Spotted Knapweed was first recorded in the park in the late 1960s, it was likely introduced when this area was used for domestic livestock grazing and ranching (that is, sometime between 1895 and 1947). Biological control agents were released into the park in 1994 and in the Blakiston Fan area in 2012. This invasive plant species continues to spread and increase in abundance throughout the Blakiston Fan (observations as of 2020; Sissons pers. comm. 2021). The long-term impacts of Spotted Knapweed are of concern because of the threat to the ecological integrity of the Blakiston Fan (Oetterich 2017; Sissons pers. comm. 2021).

Several wildfires have occurred in Waterton Lakes over the past 10 years. In 2017, the Kenow wildfire affected a portion of the Half-moon Hairstreak habitat (Sissons 2018); however, the butterfly is still present within the Blakiston Fan (Sissons pers. comm. 2019). The Boundary Wildfire (2018) and the Sofa Mountain Wildfire (1998) are also significant wildfires that occurred within the park (Parks Canada Agency 2019). These fires did not occur within habitat known to be occupied by Half-moon Hairstreak habitat, but smoke (for example, air pollution) is thought to have impacted butterfly host plant, nectar plant and habitat quality.

Biology

Life cycle and reproduction

Half-moon Hairstreak has a one-year life cycle with complete metamorphosis including four life stages (egg, four larval instars, pupa, and adult) (Layberry et al. 1998; Guppy and Shepard 2001; James and Nunnallee 2011).

The flight period for Half-moon Hairstreak is correlated with the onset of the flowering and senescence of lupines, the larval host plants (see Habitat). Oviposition has not been observed for either the Okanagan-Similkameen or Waterton Lakes populations. In other parts of the species’ range, females lay eggs on the larval host plants or in the leaf litter at the base of these plants (Scott 1986b; 1992; Pratt pers. comm. 2008 as cited in ECCC 2016). Eggs overwinter until the following spring, when the larvae hatch. Larvae (in California) likely begin feeding on spring plant growth, prior to snowmelt and under the protection of snow cover (Pratt pers. comm. 2008 as cited in ECCC 2016). In California, larvae are quite large and well developed prior to the onset of host plant flowering (Pratt pers. comm. 2008 as cited in ECCC 2016). Larval feeding has not been observed in the Okanagan-Similkameen population. In the Waterton Lake population, larvae have been observed in the litter at the base of lupine plants, with a few found on the lower part of the stems during the daytime. It is unclear whether movements of larvae have increased at night (Glasier pers. comm. 2022).

Larvae feed from April to early May, then pupate briefly before emerging as adult butterflies. The timing of the adult flight period differs between the Okanagan-Similkameen and Waterton Lakes populations, and is correlated with the flowering of lupines. In the Okanagan-Similkameen population, adult Half-moon Hairstreaks fly from late May through early July (BC CDC 2021), with a peak during the last two weeks of June (BC CDC 2021). In the Waterton Lakes population, they fly in July (COSEWIC 2006), with a peak in the last two weeks of July (COSEWIC 2006; Sissons 2018).

Physiology and adaptability

The physiology and adaptability of Half-moon Hairstreak has not been studied. However, common plants with short corollas, such as yarrow, goldenrods, and Eriogonum buckwheats provide nectar (COSEWIC 2006; Dyer et al. 2009). As is the case for some other hairstreaks (for example, Behr’s Hairstreak [Satyrium behrii], St. John pers. comm. 2020), the length of the proboscis (that is, tongue) may limit the flowers the species can access. If the depth of the corolla is greater than the length of the proboscis, the butterfly cannot reach the nectar.

Dispersal and migration

The dispersal ability of Half-moon Hairstreak has not been measured. Behr’s Hairstreak, a related species known from habitats similar to those used by the Half-moon Hairstreak, can disperse up to 5 km; however, it is unlikely to disperse across unsuitable habitat (for example, across lakes or through urban areas) (Desjardins pers. comm. 2014). Gravid females may be too heavy to fly long distances. The Half-moon Hairstreak is non-migratory.

Interspecific interactions

Evidence of bite marks on the wings of live-caught specimens suggest that the Half-moon Hairstreak may be preyed upon by small mammals, birds, and invertebrates (St. John pers. comm. 2020). Half-moon Hairstreak larvae are dependent upon lupines. Adults are not an essential pollinator of the species’ larval host plants or nectar plants.

Some Satyrium species have mutualistic relationships with ants (Formicidae): the larvae secrete a liquid containing amino acids and carbohydrates which the ants consume, and the ants protect the larvae from predators and parasitoids (Pierce 1987). Alternatively, Hairstreak larvae may ‘give’ sugar packets to prevent ants from eating the larvae, and thus minimize predation by ants. Pratt (pers. comm. 2008 as cited in ECCC 2016), who gained extensive knowledge from captive rearing butterflies, observed that these butterflies rely heavily on ants, to the extent that the ants’ presence may determine whether the butterfly species is present in some habitats. Wood ants (Formica spp.) and carpenter ants (Camponotus spp.) have been associated with Half-moon Hairstreak larvae (Pratt pers. comm. 2008 as cited in ECCC 2016).

Sissons (pers. comm. 2020) also noted ants with larvae in Waterton Lakes, and Glasier (2022) recently observed Lasius americanus and three species of wood ants (Formica argentata, F. neogagates and F. obscuripes) protecting and grooming Half-moon Hairstreak caterpillars. St. John (pers. comm. 2020) observed ants in close association with lupines in locations where Half-moon Hairstreak occurs at White Lake (#7).

Population sizes and trends

Sampling effort and methods

Half-moon Hairstreak surveys in Canada have focused on recording new subpopulations, confirming presence at a site, and gathering information on natural history, threats, and habitat. Surveys have primarily been conducted by wandering transects through suitable habitat (Table 2) (see Search effort) and tallying abundance. Abundance is an index. These surveys have not included methods that would provide estimates of population sizes or trends.

Waterton Lakes population

In addition to surveys involving wandering transects through suitable habitat (see Search effort), some controlled surveys and transects of various lengths (for example, modified Pollard Walks; Pollard 1977) have been completed (Kondla 2004, 2009; Sissons 2018) (Table 3). Starting in 2021, transects were established throughout Blakiston Fan to conduct distance sampling to acquire better population trend and habitat data (Sissons 2021). There have been no surveys using these methods in Okanagan-Similkameen habitats.

Abundance

Okanagan-Similkameen population

Half-moon Hairstreak abundance estimates are not available, and methods used to count butterflies across the years have not been consistent. The few data available cannot be compared across time (Table 1). The largest counts consist of 527 individuals identified from June 24 to 26, 2015, at Keremeos Columns/Armstrong Creek (#7), and 158 individuals identified from June 11 to 23, 2015, at South Okanagan Grasslands Protected Area (#4) (Heron pers. comm. 2021) (Table 1).

Waterton Lakes population

Methods used to derive abundance estimates for Half-moon Hairstreak have been inconsistent since the fieldwork was conducted for the first COSEWIC status report (Table 3). Surveys in 2008, 2009, 2014, and 2017 included systematic wandering transects/routes through the Half-moon Hairstreak habitat (Table 3) (Sissons 2018). Across years, there have been differences in data collection and the survey route and/or length was not always accurately recorded, plus the distance covered on either side of the transect varied (Sissons 2018) (see Table 3). The sum of all observations collected over several years was more than 190. Estimates of the number of Half-moon Hairstreaks per hectare are as high as 63, but mostly less than 30 (Table 3).

Fluctuations and trends

There is insufficient information on the abundance and distribution of Half-moon Hairstreak within the habitats in either DU to assess fluctuations or trends. Natural fluctuations in butterfly population are the result of factors such as parasites and predators, the distribution and abundance of larval and nectar host plants, and weather patterns in previous years. It is unlikely that the Half-moon Hairstreak experiences extreme population fluctuations^{Footnote 7}, as the species has never been observed in great abundance. Many sites have been visited over multiple years (Tables 2 and 3); however, these sites were visited on only one or two dates during the flight season to confirm presence, record abundance and/or assess threats to the subpopulation. There are insufficient data to conclude that extreme fluctuations have occurred. The abundance of the Waterton Lakes population appears to be declining (Sissons pers. comm. 2019).

Rescue effect

The genetic structure evidence discussed under Designatable units suggests that rescue is not possible. For completeness, the nearest occurrences are considered below.

There are few records for Half-moon Hairstreak from northern Washington State (adjacent to the Okanagan-Similkameen population) or northern Montana (adjacent to the Waterton Lakes population).

Okanagan-Similkameen population

The closest Half-moon Hairstreak record obtained south of BC (Okanagan-Similkameen population) dates to 2003 and is from the Sinlahekin Wildlife Area about 30 to 40 km south of the international border in Washington State; the specimen was collected in sagebrush grassland (Kondla pers. comm. 2021). There is a recent record from north of Sunnyslope (June 19, 2019, iNaturalist 2020) in Washington State, approximately 177 km south of the closest known records (#2 and sites at #4). Natural re-establishment from the Washington subpopulations may be possible because there is intervening sagebrush habitat. However, given the low number of newly documented sites in Canada (that is, no new subpopulations recorded since 2003) and the fragmentation of the intervening habitat, immigration is unlikely.

Waterton Lakes population

The closest known records of Half-moon Hairstreak are referenced in older publications that list records in southwestern Montana (Kohler 1980; Stanford and Opler 1993). The most recent confirmed and closest record is posted on iNaturalist (2020) and is from Carbon County in southwest Montana, about 560 km from Waterton Lakes, where the species is reported as uncommon to common (Glassberg 2001). There are no known records in intervening areas^{Footnote 8}.

The Okanagan-Similkameen and Waterton Lakes populations are naturally disjunct [see Designatable units]. The minimum (straight-line) distance between the Okanagan-Similkameen (#3) and Waterton Lakes populations (#1) is approximately 400 km. There is a large amount of unsuitable habitat in between, including the Rocky Mountains.

Threats and limiting factors

Threats

Threats to the Half-moon Hairstreak were assessed based on the IUCN-CMP (International Union for the Conservation of Nature–Conservation Measures Partnership) unified threats classification system (see Salafsky et al. 2008; Master et al. 2012). Two threat assessments were prepared: one each for the Okanagan-Similkameen population (Table 4) and the Waterton Lakes population (Table 5). Threats are summarized from the COSEWIC status report(2006) and the species recovery strategy (SIRT 2008; ECCC 2016) and updated with new information.

Table 4. Threats assessment results for the Half-moon Hairstreak (Satyrium semiluna) Okanagan-Similkameen population in Canada. The classification below is based on the IUCN-CMP (International Union for the Conservation of Nature–Conservation Measures Partnership) unified threats classification system. For a detailed description of the threats classification system, see the CMP web site (CMP 2010). Threats may be observed, inferred, or projected to occur in the next 10 years. Threats are characterized here in terms of scope, severity, and timing. Threat “impact” is calculated from scope and severity. For information on how the values are assigned, see Master et al. (2009) and the footnotes to this table

Scientific name:

Half-moon Hairstreak (Satyrium semiluna) Okanagan-Similkameen population

Date:

April 7, 2021

Assessor(s):

Brenda Costanzo (report writer), Dawn Marks (Arthropods SSC), Dave Fraser (threats assessment facilitator), John Richardson (Arthropods SSC), Leah Ramsay (Arthropods SSC), David McCorquodale (Arthropods SSC Co-chair), Jamie Lewthwaite (Arthropods SSC), Jennifer Heron (report writer), Crispin Guppy (Lepidopterist), Greg Wilson (BC COSEWIC Rep), Rosana Nobre-Soares (COSEWIC Secretariat), Natasha Lloyd (Parks Canada Agency), Robert Buchkowski (Arthropods SSC)

References:

Recovery Strategy for the Half-moon Hairstreak (Satyrium semiluna) in Canada (ECCC 2016)

Assigned overall threat impact:

C = Medium

Impact adjustment reasons:

Many of these threats are moderate and not likely to have a significant impact within the next 10 years, so there is some uncertainty with regard to when the threats will manifest themselves. Threats include invasive plants, which do not appear to impact the host lupines (for example, lupines appear abundant), although there is no quantitative evidence to support this.

Overall threat comments:

The primary threat to the Okanagan-Similkameen population consists of changes in the distribution and abundance of larval and nectar plants due to ecosystem modifications associated with fire suppression, the spread and continued introduction of invasive non-native plants, and domestic livestock overgrazing. Wildfires pose a direct threat to these same habitats. Threats facing some of the subpopulations are speculative (for example, Veronica Lake and Anarchist Mountain) because the sites have not been visited in many years. Cattle do not graze lupines; however, impacts to the habitat and to nectar plants may be substantial in places where cattle congregate, if these places coincide with Half-moon Hairstreak. Indirect effects of habitat conversion include fragmentation of the species’ population. The Richter Pass (# 5) gravel reserve licence has been owned by the Ministry of Transportation and Highways since 1985, and this area is not protected.

¹ Impact – The degree to which a species is observed, inferred, or suspected to be directly or indirectly threatened in the area of interest. The impact of each stress is based on Severity and Scope rating and considers only present and future threats. Threat impact reflects a reduction of a species population or decline/degradation of the area of an ecosystem. The median rate of population reduction or area decline for each combination of scope and severity corresponds to the following classes of threat impact: very high (75% declines), high (40%), medium (15%), and low (3%). Unknown: used when impact cannot be determined (for example, if the value for either scope or severity is unknown).

² Scope – Proportion of the species that can reasonably be expected to be affected by the threat within 10 years. Usually measured as a proportion of the species’ population, in the area, of interest. (Pervasive = 71–100%; Large = 31–70%; Restricted = 11–30%; Small = 1–10%)

³ Severity – Within the scope, the level of damage to the species from the threat that can reasonably be expected to be affected by the threat within a 10-year or three-generation timeframe. Usually measured as the degree of reduction of the species’ population (Extreme = 71–100%; Serious = 31–70%; Moderate = 11–30%; Slight = 1–10%).

⁴ Timing – High = continuing; Moderate = only in the future (could happen in the short term [< 10 years or 3 generations]) or now suspended (could come back in the short term); Low = only in the future (could happen in the long term) or now suspended (could come back in the long term); Insignificant/Negligible = only in the past and unlikely to return, or no direct effect but limiting.

Table 5. Threat assessment results for the Half-moon Hairstreak (Satyrium semiluna) Waterton Lakes population in Canada. The classification below is based on the IUCN-CMP (International Union for the Conservation of Nature–Conservation Measures Partnership) unified threats classification system. For a detailed description of the threat classification system, see the CMP web site (CMP 2010). Threats may be observed, inferred, or projected to occur in the next 10 years. Threats are characterized here in terms of scope, severity, and timing. Threat “impact” is calculated from scope and severity. For information on how the values are assigned, see Master et al. (2009) and footnotes to this table.

Scientific name:

Half-moon Hairstreak (Satyrium semiluna) Waterton Lakes population

Date:

April 7, 2021

Assessor(s):

Brenda Costanzo (report writer), Dawn Marks (Arthropods SSC), Dave Fraser (threats assessment facilitator), David McCorquodale (Arthropods SSC Co-chair), Jamie Lewthwaite (Arthropods SSC), Jennifer Heron (report writer), Crispin Guppy (Lepidopterist), Greg Wilson (BC Rep), John Richardson (Arthropods SSC), Leah Ramsay (Arthropods SSC), Rosana Nobre-Soares (COSEWIC Secretariat), Natasha Lloyd (Parks Canada Agency), Robert Buchkowski (Arthropods SSC), Robert Sissons (Parks Canada Agency)

References:

Recovery Strategy for the Half-moon Hairstreak (Satyrium semiluna) in Canada (ECCC 2016)

Assigned overall threat impact:

C = Medium

Impact adjustment reasons:

No adjustment.

Overall threat comments:

Waterton Lakes population. The primary threat appears to be the spread of non-native plants, such as Spotted Knapweed, which are causing ecosystem modifications to the habitat and contributing to the decline in abundance and quality of larval host and adult nectar plants.

¹Impact – The degree to which a species is observed, inferred, or suspected to be directly or indirectly threatened, in the area, of interest. The impact of each stress is based on Severity and Scope rating and considers only present and future threats. Threat impact reflects a reduction of a species population or decline/degradation of the area of an ecosystem. The median rate of population reduction or area decline for each combination of scope and severity corresponds to the following classes of threat impact: very high (75% declines), high (40%), medium (15%), and low (3%). Unknown: used when impact cannot be determined (for example, if the value for either scope or severity is unknown).

²Scope – Proportion of the species that can reasonably be expected to be affected by the threat within 10 years. Usually measured as a proportion of the species’ population, in the area, of interest. (Pervasive = 71–100%; Large = 31–70%; Restricted = 11–30%; Small = 1–10%)

³Severity – Within the scope, the level of damage to the species from the threat that can reasonably be expected to be affected by the threat within a 10-year or three-generation timeframe. Usually measured as the degree of reduction of the species’ population (Extreme = 71–100%; Serious = 31–70%; Moderate = 11–30%; Slight = 1–10%).

⁴Timing – High = continuing; Moderate = only in the future (could happen in the short term [< 10 years or 3 generations]) or now suspended (could come back in the short term); Low = only in the future (could happen in the long term) or now suspended (could come back in the long term); Insignificant/Negligible = only in the past and unlikely to return, or no direct effect but limiting.

Okanagan-Similkameen population

The primary threat to the Okanagan-Similkameen population consists of changes to the distribution and abundance of larval and nectar plants due to ecosystem modifications associated with fire suppression, the spread and continued introduction of invasive non-native plants, and domestic livestock overgrazing. Wildfires are direct threats to these same habitats. The overall threat impact to this population is Medium (Table 4).

Indirect effects of habitat conversion include fragmentation of the species’ population. The Richter Pass (# 5) gravel reserve licence has been owned by the Ministry of Transportation and Highways since 1985, and this area is not protected.

Waterton Lakes population

The primary threat appears to be the spread of non-native plants, such as Spotted Knapweed, which is causing ecosystem modifications to the habitat and contributing to the decline in abundance and quality of larval host and adult nectar plants. The overall threat impact to this population is Medium (Table 5).

Details are discussed below under the IUCN-CMP unified threats classification system headings and numbering scheme.

Threat 7. Natural system modifications (high to low impact, Okanagan-Similkameen; medium impact, Waterton Lakes)

7.1 Fire and Fire suppression. Wildfire is scored under this subheading (7.1). Fire suppression is scored under threat 7.3.

Okanagan-Similkameen population

Impact: high–low.

Frequent, low-intensity wildfires were historically more common throughout the Okanagan and Similkameen valleys. Fires were attributable to burns started by First Nations peoples to improve root crops and to lightning (Cannings and Durance 1998; Iverson 2012). The Okanagan Valley grasslands area historically experienced frequent, low-intensity fires that limited the growth of woody plants (Gayton 2003). Fires are now less frequent, due to active fire suppression since the 1940s; however, they are more intense, because of the higher fuel loads associated with encroaching fire-intolerant shrubs such as Antelope-brush (Purshia tridentata) and non-native Cheatgrass. Wildfire severity and intensity are increasing as a result of fire suppression activities and climate change (Spittlehouse 2008). An extensive wildfire at White Lake (#3) in 2014 eliminated one of the two main Half-moon Hairstreak areas (Dyer pers. comm. 2020). Lupines will increase in abundance within 5 to 10 years after a fire if there is enough moisture (Guppy pers. comm., 2021). This would increase food supplies for Half-moon Hairstreak larvae. These post-fire disturbed sites are also subject to invasions of exotic species that affect ecosystem processes (Gayton 2003; scored under 7.3).

Waterton Lakes population

Impact: medium

Extensive wildfires burned throughout the open lowland and forested regions of WLNP in 1998, 2017, and 2018 (Parks Canada Agency 2019). A portion of the Blakiston Fan burned in the 2017 fire but did not burn in the 1998 or 2018 fires. Extensive smoke may affect air quality for active larvae and/or adult butterflies and food plant quality. Fires are anticipated to be more frequent and severe in the future (de Groot et al. 2002; Flannigan et al. 2005).

Silky Lupine is generally enhanced by or not affected by fire (Johnson et al. 1987). This lupine species has a deep root system allowing it to survive after fire, and it is able to resprout from the caudex (Lyon et al. 1976). After a disturbance, Silky Lupine can germinate from buried seed (Matthews 1993). Within the Blakiston Fan, both Silvery and Silky Lupines rebounded after the 2017 Kenow fire; however, so did invasive Spotted Knapweed. As a result of the increase in Spotted Knapweed, Half-moon Hairstreak eggs near the soil surface were suspected to have been lost (Sissons pers. comm. 2021).

7.3 Other ecosystem modifications

Other ecosystem modifications include the cumulative effects of threats that alter ecosystem functions, services, quality, and quantity. While these threats do not directly kill the butterflies, they adversely affect the ecosystem and available habitat, rendering it less suitable for Half-moon Hairstreak.

Okanagan-Similkameen population

Impact: low

The cumulative effects of livestock overgrazing (2.3), fire suppression (7.1), and the spread of non-native/alien (8.1) and native plants (8.2) have contributed to a decline in the quality and quantity of habitat available for Half-moon Hairstreak. Non-native Cheatgrass (Bromus tectorum), Dalmatian Toadflax (Linaria genistifolia ssp. dalmatica), Diffuse Knapweed (Centaurea diffusa) and Sulphur Cinquefoil (Potentilla recta) are invasive plants with horizontally spreading surface roots that have been recorded throughout the habitats where Half-moon Hairstreak occurs. Sulphur Cinquefoil can form monospecific stands (SIRT 2008). These plants grow into and occupy open soil areas and slow or prevent the establishment of native vegetation, thereby modifying the habitat and making it less suitable for host and nectar plants.

Over the past 100 years, fire suppression programs have altered the natural fire regime within the Okanagan and Similkameen valleys. Fire suppression has resulted in a build-up of fuels on the ground. As a result, more intense, stand-replacing fires may occur instead of the less intense patchy fires that leave sagebrush ecological community patches intact. Reduced wildfire frequency leads to tree encroachment, which in turn reduces the size and extent of bare soil and open sandy areas available for healthy larval host and nectar plant populations.

Lupines (larval host plant) are early successional plants; they are able to sprout from the base of the plant stem or germinate from seeds in the soil after fires (USDA-USFS 2021). Lupines nonetheless need some moisture in the summer or conditions will be too dry for their future growth. Certain types of fires (for example, patchy fires) can be beneficial to lupine reproduction and spread, as these fires leave more open areas, competition from other plants is reduced, and more sunlight is available, thus allowing the lupines to regenerate. Conversely, if there is a lack of fire disturbance, succession is altered and the lupines will die out due to the increased shade under trees, plus increased competition from shrubs and grasses/forbs all of which are not conducive to lupine growth and reproduction.

Livestock overgrazing can result in trampling of larval host plants and adult nectar plants, changes in soil nutrient content caused by the animals’ urination and defecation, as well as soil compaction. Livestock also consume flowering/nectar plants, reducing the abundance of these plants during the adult flight period. The first COSEWIC status report (2006) states that livestock grazing is likely a factor in population dynamics for Half-moon Hairstreak on lands that are subject to “extremely intense and persistent grazing”. At Richter Pass (#5), the butterfly is exposed to a fairly high level of livestock grazing. In contrast, at White Lake (#7) individuals have been found in an area subject to light grazing. None were seen at a nearby heavily grazed site (COSEWIC 2006). Livestock grazing also increases the introduction and spread of invasive plants (see above).

Waterton Lakes population

Impact: medium

Spotted Knapweed is a non-native plant that is well-established throughout the Blakiston Fan (Oetterich 2018; Sissons pers. comm. 2019). The plant has spread throughout this area and appears to have contributed to the decline in the quality and quantity of Half-moon Hairstreak habitat (Sissons pers. comm. 2019). Seeds germinate in the fall of the year and can remain viable for more than 8 years (Davis et al. 1993). Spotted Knapweed seeds can be transported by native species (for example, in the fur of ungulates) and anthropogenic means (for example, attaching to shoes, vehicle tires). The plant produces dense monotypic stands. The long-term ecological changes associated with Spotted Knapweed include reduced soil water filtration and increased surface water runoff and stream sedimentation (Lacey et al. 1989). Spotted Knapweed secretes catechin, a phytotoxin, from its roots. Catechin decreases the growth of many plants, including prairie grasses (Ridenour and Callaway 2001), and promotes monotypic stands of knapweed. Lupines, which are a food source for the Half-moon Hairstreak, are less susceptible to these phytotoxic properties than many plants (Weir et al. 2005; Alford et al. 2009). There is some evidence that symbiotic rhizobia provide protection from the toxicity of catechin for Silky Lupine, and therefore it is a useful species for carrying out habitat restoration after invasion by Spotted Knapweed (Alford et al. 2009). In Waterton Lakes, knapweed likely outcompetes lupines and nectar plants and causes changes in the soil chemistry and invertebrate ground fauna (for example, ants). There are also some agronomic grasses that are reducing habitat for Half-moon Hairstreak (for example, Cheatgrass or Smooth Brome [Bromus inermis] and are difficult to control (Sissons pers. comm. 2021).

Threat 11 Climate change and severe weather (low impact, Okanagan-Similkameen; low impact, Waterton Lakes)

Climate change is a potential but poorly understood threat to the ecosystems in both the Okanagan-Similkameen and Waterton Lakes populations.

11.2 Droughts

Changes in the intensity, frequency, and longevity of droughts could affect the long-term survival and abundance of host and nectar plants bloom time as well as the start of senescence.

Okanagan-Similkameen population. Impact: low. Available models predict the climate will become drier in the summer and the frequency and duration of summer droughts will increase in the Okanagan Valley (Spittlehouse 2008; Haughian et al. 2012). The larval host plants are drought tolerant thanks to their deep tap root and can also re-establish after fire either by sprouting from their caudex (base of the stem) or germinating from seed banks in the soil (USDA-USFS 2021). Silky Lupine is a cool-season plant that begins its growth in May and typically flowers from June to July, or in August and September within its range. The seeds are disseminated in August and the plants dry up by the end of August (USDA-USFS 2021). Larvae feed starting in May and are not likely to encounter premature seasonal plant senescence. However, drought may impact adult nectar plants, such as Parsnip-flowered Buckwheat (Eriogonum heracleoides). In 2015, a particularly dry summer, these buckwheat plants withered (Marks 2022).

Waterton Lakes population

Impact: low

In AB, there is expected to be a mean annual temperature increase (2 to 6^oC) and a small increase in mean annual precipitation in winter and spring by the 2080s (Barrow and Yue 2005; Parks Canada Agency 2017). Soil moisture will subsequently decrease and is predicted to decline by 20% to 30% in western AB (Schindler and Donahue 2012). Southeastern BC (for example, adjacent to WLNP) will also experience an increase in mean annual precipitation in the winter and spring and a decrease in summer precipitation (Spittlehouse 2008; Walker and Sydneysmith 2008). The frequency, intensity, and duration of drought are projected to increase (Gillett et al. 2004).

11.4 Storms and flooding

Waterton Lakes population

Impact: low

The current frequency of flooding is normal in the Blakiston Fan; however, climate models predict that high levels of flooding may occur (Parks Canada Agency 2017; Sissons pers. comm. 2021).

Threat 1. Residential or commercial development (low impact, Okanagan-Similkameen)

1.1 Housing and urban areas

Okanagan-Similkameen population

Impact: low

Direct and irreversible physical destruction of grassland habitat (for example, construction of housing developments) is ongoing throughout the Okanagan Valley, although little of the habitat used by Half-moon Hairstreak subpopulations appears to be affected. Portions of five subpopulations (#2, #3, #4, #5, #6) are on private land (Land Title and Survey Authority of British Columbia 2022); however, all of these areas are rural and not within areas zoned for redevelopment. Since the 2006 status assessment (COSEWIC 2006), private land parcels occupied by subpopulation #4 have been purchased by the Nature Conservancy of Canada and are being managed for conservation purposes. Together, they are now known as the Sage and Sparrow Conservation Area (Nature Conservancy of Canada 2020). Private land within subpopulations #2, #3, and #5 is highlighted as Environmentally Sensitive in the Regional District of Okanagan-Similkameen’s Environmentally Sensitive Development Permit (ESDP) mapping (Regional District of Okanagan-Similkameen 2022). ESDP areas highlight parcels that have been designated for the protection of natural biodiversity. Subdivision or building within these areas requires an environmental impact assessment by a qualified environmental professional (Regional District of Okanagan-Similkameen 2020). In the 1970s, a lot of rural development took place near #3 (Anarchist Mtn.), and between 2004 and 2008 subdivision of the “Regal Ridge” development was initiated (now Osoyoos Mountain Estates). This trend has slowed recently, but any fragmentation of sagebrush communities is expected to reduce re-occupancy rates after natural stochastic events (based on observations of Behr’s Hairstreak in the south Okanagan; SIRT 2008).

Threat 2. Agriculture and aquaculture (low impact, Okanagan-Similkameen)

2.1 Annual and perennial non-timber crops

Okanagan-Similkameen population

Impact: low

Natural habitat conversion and/or agricultural crop conversion/intensification can affect Half-moon Hairstreak habitats on private lands (#2 and 3, portions of #5 and #6). These properties are large natural areas with apparently intact native plant communities; however, the adjacent properties are agricultural land. The potential for development of these intact natural areas is therefore high. Vineyards can be established at elevations up to 490 m (British Columbia Ministry of Agriculture and Lands 2010), which would likely not affect these four Half-moon Hairstreak subpopulations (#2 > 548 m; #3 > 800 m; #5 >700 m; #6 > 900m; Table 1).

2.3 Livestock farming and ranching

Okanagan-Similkameen population

Impact: unknown

Impacts from livestock are scored based on direct consumption of larvae, trampling of larvae, overwintering pupae, or puddling adults (possible). Livestock graze in some Half-moon Hairstreak habitats (#2, 6, and 7) but the intensity varies from site to site, and is unknown. Cattle rarely eat lupines (that is, larval host plants); however, nectar plants are consumed. Ecosystem modifications that result from livestock overgrazing and resultant habitat changes are scored under 7.3.

Threat 9. Pollution (low impact, Okanagan-Similkameen)

9.3 Agricultural and forestry effluents

Okanagan-Similkameen population

Impact: low

There is potential for herbicide overspray that affects non-native plants (for example, spray application is across a broad area and not targeted at specific plants; as a result all plants in an area are adversely impacted). On private lands (#2 and #3) and the roadside portion of #3 (a provincial rest stop), herbicide overspray may impact non-target larval and nectar host plants by killing both the plant and/or larvae that are present on the plant. Pesticide overspray may also occur along roadsides adjacent to White Lake (#7) and the portion of Anarchist Mountain (#3) managed by the Ministry of Transportation, Infrastructure, and Highways (MOTH). Herbicide treatments that target non-native plants are not likely to occur near subpopulations within protected areas (#4, portion of #5, #6, and #7). Pesticide drift from adjacent agricultural areas may impact Half-moon Hairstreak subpopulations through direct mortality at localized sites, but the impacts have not been documented.

Waterton Lakes population. Impact: unknown. Spotted Knapweed appears to be increasing in abundance throughout the Blakiston Fan (Oetterich 2018; Sissons pers. comm. 2019). Herbicides have been tested with the aim of controlling the plant (Oetterich 2018). Should herbicides be used in the future, there would be careful consideration for species at risk, including Half-moon Hairstreak. (Oetterich 2018; Sissons pers. comm. 2019).

Threat 8. Invasive and other problematic species and genes (unknown impact, Okanagan-Similkameen and Waterton Lakes)

8.1 Invasive non-native/alien species

Okanagan-Similkameen and Waterton Lakes populations

Impact: unknown

Compsilura concinnata (Diptera: Tachinidae) is a non-native parasitic fly introduced into eastern North America as a biological control agent for European Spongy Moth (Lymantria dispar). This fly may affect Half-moon Hairstreak (Boettner et al. 2000) and may be present in BC and AB (GBIF Secretariat 2019). Non-native invasive plants, which alter the available habitat, but do not cause direct mortality to butterflies, are discussed under 7.3, Other ecosystem modifications.

Limiting factors

Limiting factors are innate characteristics that make Half-moon Hairstreak vulnerable to ongoing threats. The main limiting factors for Half-moon Hairstreak are summarized from the recovery strategy (SIRT 2008; ECCC 2016):

Larval host plant specificity

Half-moon Hairstreak is dependent on lupines as larval host plants and without these plants the butterfly cannot complete its life cycle (see Habitat). Adults forage for nectar opportunistically.

Small population size

Half-moon Hairstreak subpopulations occur within small, isolated, and limited habitat patches. Some subpopulations (#4) have more than 400 individuals. However, the species appears to occur as small or localized subpopulations. For the Waterton Lakes population, fewer than 1,000 individuals have been observed in 15 years of surveys, suggesting a population of a few hundred individuals at most (that is, 2004–2019) (Table 3).

Natural parasites

Parasitic wasps impact butterflies during all life stages; however, no species-specific information is available for Half-moon Hairstreak.

Vulnerability to weather patterns

The previous year’s weather affects the abundance of the next year’s generation of butterflies. Extreme differences in frost, temperature, degree-days, humidity, and precipitation affect survival at all life stages. These factors contribute to the numbers that emerge in the next generation.

Limited dispersal capability

Half-moon Hairstreak is small and does not likely disperse long distances (< 5 km), especially through unsuitable habitats. Insularity in subpopulations may lead to decreased genetic diversity, greater genetic differences, inbreeding depression, and no rescue effect.

Myrmecophily

Myrmecophily is the mutualistic relationship between larval hairstreaks and adult ants (see Habitat). It is likely that ants are critical for oviposition and the survival of subpopulations (St. John pers. comm. 2020) (see Interspecific interactions).

Short adult life cycle

Adult butterflies have a short flight season and individuals live approximately two weeks. Inclement weather and the premature senescence of host plants, combined with the short flight period, small size, limited dispersal ability, and declining habitat quality and quantity, may limit growth of the subpopulation.

Number of locations

Okanagan-Similkameen population

A minimum of six locations^{Footnote 10} based on differing land management and variable threats to the habitat where each of the six subpopulations occurs (see Table 1; Figure 7).

Waterton Lakes population

One location based on the threat of ecosystem changes due to the presence of non-native/invasive Spotted Knapweed within Half-moon Hairstreak habitat in WLNP.

Protection, status and ranks

Legal protection and status

Federal protection

Half-moon Hairstreak was assessed as one designatable unit and listed as Endangered under the federal Species at Risk Act on December 13, 2007. Critical habitat has been described (ECCC 2016). The Alberta subpopulation, assessed as one DU, is located entirely within WLNP and is also protected under the Canada National Parks Act. A portion of the subpopulation at White Lake (#7) is on federal land.

Provincial protection

Two Half-moon Hairstreak subpopulations (#4 and #5) span three parcels of a large provincially protected area (South Okanagan Grasslands Protected Area [Table 1]). The BC Park Act protects invertebrate species at risk (provincially assessed as Red or Blue-listed by the BC Conservation Data Centre) in provincial parks and protected areas. When species at risk and the habitats they require are known to occur within a protected area, provisions for management are incorporated into the park master plan. Provincial park staff within the range of Half-moon Hairstreak are aware of the species’ presence at sites within the sagebrush ecological communities. When scientific research permits and other activities within parks and protected areas are proposed, parks staff consider the adverse impacts of the proposed activities on the butterfly and its habitat (Bunge pers. comm. 2019; Safford pers. comm. 2019; Weston pers. comm. 2019).

The BC Forest and Range Practices Act and the Oil and Gas Activities Act are applicable to species defined as Identified Wildlife and occupying habitat on provincial land managed for forest resources, grazing leases, and oil and gas extraction. Species can be listed as Identified Wildlife, which enables habitat for the species to be spatially protected within wildlife habitat areas. Half-moon Hairstreak is listed under these Acts, and 15 wildlife habitat areas totalling 383.6 ha have been created to protect the species (BCMOE 2019); most of these are within the South Okanagan Grasslands Protected Area and others are located northeast of Keremeos and one near White Lake.

Non-legal status and ranks

The conservation status ranks for Half-moon Hairstreak:

Global Status G4 (Apparently Secure) (NatureServe 2020)

Canada National Status N1 (Critically Imperilled) (NatureServe 2020)

British Columbia S1 (Critically Imperilled) (BC CDC 2021)

Alberta S1 (Critically Imperilled) (ANHIC 2020)

United States N4 (Apparently Secure) (Natureserve 2020)

Subnational state ranks California (SNR), Colorado (S3), Idaho (S3), Montana (S4), Nevada (SNR), Oregon (SNR), Utah (SNR), Washington (S4), Wyoming (SNR) (NatureServe 2020).

Habitat protection and ownership

Half-moon Hairstreak surveys in the past 10 years have contributed to the creation of 15 wildlife habitat areas that protect the species under the BC Forest and Range Practices Act. Okanagan-Similkameen subpopulations of Half-moon Hairstreak have been recorded from private properties (#2, #3 [in part], #5 [in part], and #6 [in part]), one is private conservation lands (#4 [in part]) and one managed by private conservation organization (#7 [in part]), three parcels of a provincial protected area (#4 [in part], and #5 [in part]), one federal property leased to a private ranch operator (#7 [in part]) and two unprotected provincial sites (#3 [in part], #6 and #7). Land management within these properties is variable (see Threats).

The entire Waterton Lakes population is in the Blakiston Fan at Waterton Lakes National Park (population #1) which is identified as critical habitat under SARA. There is clear signage at the periphery of this habitat asking visitors to stay on designated trails.

In British Columbia, non-government conservation organizations, such as The Land Conservancy, The Nature Trust, and the South Okanagan Similkameen Conservation Program (and affiliated organizations) work with private landowners to protect arthropod species at risk on private lands. Should additional information become available on Half-moon Hairstreak, these organizations may initiate stewardship actions within their current management and outreach networks.

Acknowledgements

The status report writers would like to thank the British Columbia Ministry of Environment and Climate Change Strategy (ENV) for providing time and resources to complete this report. The following people provided field support: Denis Knopp, Dennis St. John, Dawn Marks, Kyle Grant, Cara Dawson, Kirk Safford, Orville Dyer, Sara Bunge, Mark Weston, Josie Symonds, Katie Calon, Jamie Leatham, Claudia Copley, Lea Gelling, Leah Ramsay, Crispin Guppy, Norbert Kondla, Cory Sheffield, Wendy Pope, Eric Gross, Purnima Govindarajulu, and Manjit Kerr-Upal. Ann Potter (Washington Department of Fish and Wildlife) provided information about the species in Washington State. Claudia Copley (Royal BC Museum, Victoria) and Karen Needham (Spencer Entomological Collection, Beaty Biodiversity Museum at the University of British Columbia) provided access to museum specimens. Robert Sissons (Parks Canada Agency) and Kim Pearson (Parks Canada Agency) provided information on the Waterton Lakes population, habitat, and potential threats in WLNP. Zachary MacDonald, Julian Dupuis, Felix Sperling, and other collaborators generously provided a summary of their work on the population genetic structure of these hairstreaks.

COSEWIC reviews added value, including from members of the Arthropods Specialist Subcommittee (Robert Buchkowski, Syd Cannings, Jeremy de Waard, Allan Harris, Colin Jones, John Klymko, Jayme Lewthwaite, Jessica Linton, Dawn Marks, Jeff Ogden, Leah Ramsay, John Richardson, Michel Saint-Germain, Sarah Semmler, Brian Starzomski, Myrle Ballard and Dan Benoit), and individuals from the jurisdictions and government departments (Purnima Govindarajulu, Robert Sissons, Pippa Shepard, Leah deForest, and Gina Schalk). Jenny Wu, Alain Filion, and Sydney Allen (COSEWIC Secretariat), and Greg Amos (ENV) provided mapping support. David McCorquodale (Arthropods SSC Co-chair), Rosana Nobre Soares and Joanna James (COSEWIC Secretariat) provided oversight throughout the process.

Norbert Kondla and Crispin Guppy wrote the first COSEWIC status report (2006).

Cover photograph of Half-moon Hairstreak, taken on June 19, 2019, at White Lake (#7) BC, by Jennifer Heron. Specimen was not collected.

Authorities contacted

Bunge, Sarah. Parks and Protected Areas, BC Ministry of Environment and Climate Change Strategy, Penticton Office, Penticton, British Columbia.

Burdock, Nicolas. The Nature Trust of British Columbia. Penticton, British Columbia.

Cannings, Syd. Canadian Wildlife Service, Environment and Climate Change Canada, Whitehorse, Yukon.

Copley, Claudia. Entomology Collections Manager, Royal British Columbia Museum, Victoria, British Columbia.

Desjardins, Sylvie. Associate Professor. University of British Columbia – Okanagan Campus, Kelowna, British Columbia.

Dyer, Orville (retired). Amphibians, Reptiles and Small Mammals Species at Risk Biologist, Ministry of Environment and Climate Change Strategy, Penticton, British Columbia.

Fraser, David (retired). Unit Head, Species at Risk Conservation Unit, Ecosystems Branch, BC Ministry of Environment and Climate Change Strategy, Victoria, British Columbia.

Gatten, Jeremy. Lepidopterist, Victoria, British Columbia.

Gelling, Lea. Zoologist, BC Conservation Data Centre, Victoria, British Columbia.

Govindarajulu, Purnima. Unit Head, Species at Risk Conservation Unit, Ecosystems Branch, BC Ministry of Environment and Climate Change Strategy, Victoria, British Columbia.

Guppy, Crispin. Lepidopterist, Whitehorse, Yukon.

Haney, Allison. Biologist and GIS Specialist, Summerland, British Columbia.

Harrison, Megan. Species at risk biologist. Canadian Wildlife Service, Environment Canada, Delta, British Columbia.

Goulet, Gloria. Co-chair Aboriginal Traditional Knowledge COSEWIC Subcommittee, Manitoba.

Knopp, Denis. BC’s Wild Heritage Consulting, Sardis, British Columbia.

Kondla, Norbert. Lepidopterist, Calgary, Alberta.

Leatham, Jamie. BC Ministry of Forests, Lands and Natural Resource Operations, Penticton, British Columbia.

Marks, Dawn. BC Conservation Foundation, Surrey, British Columbia.

Needham, Karen. Spencer Entomological Collection, Beaty Biodiversity Museum at the University of British Columbia, Vancouver, British Columbia.

Page, Nick. Biologist, Raincoast Applied Ecology, Vancouver, British Columbia.

Pearson, Kim. Ecosystem Scientist, Waterton Lakes National Park, Parks Canada Agency, Waterton Park, Alberta.

Pohl, Greg. Insect/Disease Identification Officer, Northern Forestry Centre, Natural Resources Canada, Northwest Edmonton, Alberta.

Potter, Ann. United States Fish and Wildlife Service, Olympia, Washington, USA.

Safford, Kirk. Conservation Specialist, BC Parks and Protected Areas, Penticton, British Columbia.

St. John, Dennis. Private Entomologist, Agassiz, British Columbia.

Schmidt, B. Christian. Entomologist. National Collection of Insects, Arachnids and Nematodes, Ottawa, Ontario.

Sheffield, Cory. Invertebrates Curator. Royal Saskatchewan Museum, Regina, Saskatchewan.

Sissons, Robert A. Ecologist - Restoration and Vegetation, Waterton Lakes National Park of Canada, Parks Canada Agency, Waterton Park, Alberta.

Sperling, Felix. Curator of the E.H. Strickland Entomological Museum. University of Alberta, Edmonton, Alberta.

Symonds, Josie. BC Ministry of Forests, Lands, Natural Resource Operations and Rural Development, Penticton, British Columbia.

Weston, Mark. BC Parks and Protected Areas, BC Ministry of Environment and Climate Change Strategy, Penticton, British Columbia.

Information sources

Achuff, P.L., R.L. McNeil, M.L. Coleman, C. Wallis, and C. Wershler. 2002. Ecological land classification of Waterton Lakes National Park, Alberta. Vol. I: Integrated resource description. Parks Canada, Waterton Park, Alberta. 226 pp.

Alcock, W., and M. Sarell. 2014. Half-moon Hairstreak (Satyrium semiluna) Inventory Surveys in the South Okanagan and Similkameen Valleys, 2014. Ministry of Forests, Lands and Natural Resource Operations, Penticton, British Columbia. 44 pp.

Alford, E.R., J.M. Vivanco, and M.W. Paschke. 2009. The Effects of Flavonoid Allelochemicals from Knapweeds on Legume–Rhizobia Candidates for Restoration. Restoration Ecology 17:506-514.

Ballmer, G.R., and G.F. Pratt. 1988. A survey of the last instar larvae of the Lycaenidae (Lepidoptera) of California. Journal of Research on the Lepidoptera 27:1-81.

Barrow, E., and G. Yu. 2005. Climate scenarios for Alberta: report prepared for the Prairie Adaptation Research Collaborative, Regina, Saskatchewan in cooperation with Alberta Environment. 73 pp

Blanchette, S-A., L. Machial, and A. Moore. 2007. Invertebrate species at risk butterflies of the south Okanagan and Kootenays (surveys). British Columbia Conservation Corps, electronic butterfly database and report for 2007. British Columbia Ministry of Environment, Internal Working Report, Victoria, British Columbia. October 9, 2007.

Boettner, G.H., J.S. Elkinton, and C. Boettner. 2000. Effects of a biological control introduction on three nontarget native species of saturniid moths. Conservation Biology 14:1796-1806.

BC CDC (British Columbia Conservation Data Centre). 2021. BC Species and Ecosystems Explorer. BC Ministry of Environment, Victoria, British Columbia Website: http://a100.gov.bc.ca/pub/eswp/ [accessed August 6, 2021].

BC CDC. (British Columbia Conservation Data Centre). 2022. B.C. Conservation Data Centre. Website: https://www2.gov.bc.ca/gov/content/environment/plants-animals-ecosystems/conservation-data-centre [accessed 23 December 2022].

British Columbia Ministry of Agriculture and Lands. 2010. 2010 Best Practices Guide for Grapes for British Columbia Growers. https://www.bcwgc.org/best-practices-guide [accessed June 23, 2021]

British Columbia Ministry of Environment (BCMOE). 2019. Approved Wildlife Habitat Areas http://www.env.gov.bc.ca/wld/frpa/iwms/wha.html [accessed December 27, 2019].

Brookes, W., L.D. Daniels, K. Copes-Gerbitz, J.N. Baron, and A.L. Carroll. 2021. A Disrupted Historical Fire Regime in Central British Columbia. Frontiers in Ecology and Evolution 9:676961 https://doi.org/10.3389/fevo.2021.676961 [accessed January 26, 2022].

Bunge, S., pers. comm 2019 to 2021. Email correspondence and personal communication with Jennifer Heron and Dawn Marks. BC Parks and Protected Areas, Ministry of Environment and Climate Change Strategy, Penticton, British Columbia.

CCIS (Canadian Council on Invasive Species). 2021. Degradation of the Natural Environment. https://canadainvasives.ca/invasive-species/ [accessed May 25, 2021].

Cannings, R.J., and E. Durance. 1998. Human use of natural resources in the South Okanagan and Lower Similkameen valleys. In: Smith, I.M., and G.G.E. Scudder, eds. Assessment of species diversity in the Waterton Lakes Ecozone. Burlington: Ecological Monitoring and Assessment Network, 1998.

Cannings, R.J., E. Durance, and L.K. Scott. 1998. South Okanagan ecosystem recovery plan: scientific assessment. British Columbia Ministry of Environment, Lands and Parks, Penticton, British Columbia.

Conservation Measures Partnership (CMP). http://www.conservationmeasures.org/ [accessed December 14, 2020].

COSEWIC. 2006. COSEWIC Assessment and Status Report of the Half-moon Hairstreak Satyrium semiluna in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 26 pp.

COSEWIC. 2012. COSEWIC assessment and status report on the Behr’s Hairstreak Satyrium behrii in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. x + 48 pp.

Davis, E.S., P.K. Fay, T.K. Chincoine, and C.A. Lacey. 1993. Persistence of spotted knapweed (Centaurea maculosa) seed in soil. Weed Science 41:57-61.

de Groot, W., P. Bothwell, D. Carlsson, K. Logan, R. Wein, and C. Li. 2002. Forest fire management adaptation to climate change in the Prairies. Canadian Forest Service, University of Alberta, and Prairie Adaptation Research Collaborative, Regina, Saskatchewan. 97 pp.

de Waard, J., pers. comm. 2021. Emails to Jennifer Heron. Lepidopterist and Associate Director – Collections, Centre for Biodiversity Genomics, University of Guelph, Guelph, Ontario.

Desjardins, S., 2014. pers. comm. and data to Orville Dyer and Jennifer Heron. Associate Professor, University of British Columbia – Okanagan Campus, Kelowna, British Columbia.

Dyer, O., 2019 and 2020. pers. comm. Email correspondence and personal communication with Jennifer Heron. Retired Species at Risk Biologist, Ministry of Environment and Climate Change Strategy, Penticton, British Columbia.

Dyer, O., V. Young, and D. Marks. 2009. 2009 Multi-Species Surveys Southern Interior BC Okanagan Region Project. Ministry of Environment. Species Inventory Web Explorer. http://a100.gov.bc.ca/pub/siwe/details.do?projectId=4626&pagerOffset=0 [accessed December 10, 2020].

eButterfly. 2021. An international, data driven project dedicated to butterfly biodiversity, conservation, and education: Satyrium semiluna

Environment Canada.1999. Invasive Plants of Natural Habitats in Canada: An Integrated Review of Wetland and Upland Species and Legislation Governing their Control https://cvc.ca/wp-content/uploads/2011/03/invasives.pdf [accessed May 25, 2021].

Environment and Climate Change Canada (ECCC). 2016. Recovery Strategy for the Half-moon Hairstreak (Satyrium semiluna) in Canada. Species at Risk Act Recovery Strategy Series. Environment and Climate Change Canada, Ottawa. 2 parts, 24 pp. and 33 pp. https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/recovery-strategies/half-moon-hairstreak-2016.html [accessed December 27, 2019].

ESTR Secretariat. 2014. Western Interior Basin Ecozone⁺ evidence for key findings summary. Canadian Biodiversity: Ecosystem Status and Trends 2010, Evidence for Key Findings Summary Report No. 11. Canadian Councils of Resource Ministers. Ottawa, Ontario. viii + 106 pp. Website: https://static1.squarespace.com/static/613fb778a76e244eef08775d/t/61b78d23ffbfc059daa14f6c/1639419179236/E-WIB+EKFS+FINAL_2014-05-06.pdf[accessed December, 23 2022]

Flannigan, M.D., K.A. Logan, B.D. Amiro, W.R. Skinner, and B.J. Stocks. 2005. Future area burned in Canada. Climate Change 72:1-16.

Gayton, D. 2003. British Columbia grasslands: monitoring vegetation change. Forrex, Kamloops, British Columbia.

GBIF (Global Biodiversity Information Facility) Secretariat (2019). Compsilura concinnata (Meigen, 1824). Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei. [accessed via www.GBIF.org on December 12, 2020].

Gillett, N.P., A.J. Weaver, F.W. Zweirs, and M.D. Flannigan. 2004. Detecting the effect of climate change on Canadian forest fires. Geophysical Research Letters 31: L18211.

Glasier, J., pers. comm. 2022. Email correspondence with Leah deForest and David McCorquodale. Population Ecologist, Wilder Institute, Calgary, Alberta.

Glassberg, J. 2001. Butterflies through Binoculars: A Field Guide to the Butterflies of Western North America. Oxford University Press.

Guppy, C.S. pers. comm. 2021. Email correspondence with Jennifer Heron. Lepidopterist, Whitehorse, Yukon Territory.

Guppy, C.S., and J.H. Shepard. 2001. Butterflies of British Columbia. University of British Columbia Press, Vancouver, British Columbia.

Haney, A., and J. Heron. 2014. Surveys for Behr’s Hairstreak (Satyrium behrii columbia) in the Antelope-brush Grasslands of British Columbia, 2014. BC Ministry of Environment unpublished report, Vancouver, British Columbia. 62 pp.

Haughian, S.R., P.J. Burton, S.W. Taylor, and C.L. Curry. 2012. Expected effects of climate change on forest disturbance regimes in British Columbia. BC Journal of Ecosystems and Management 13:1–24. https://jem-online.org/index.php/jem/article/view/152

Heron, J., and C. Sheffield. 2016. Summary report Year 1 of 3: Habitat stewardship actions for pollinators in the Thompson-Okanagan and Similkameen Valleys, British Columbia, 2016. BC Ministry of Environment, Vancouver, British Columbia. 290 pp.

Heron, J., C. Sheffield, and D. Marks. 2017. Summary report Year 2 of 3: Habitat stewardship actions for pollinators in the Thompson-Okanagan and Similkameen Valleys, British Columbia, 2017. BC Ministry of Environment and Climate Change Strategy, Vancouver, British Columbia. 59 pp. + 3 Appendices.

Heron, J., C. Sheffield, and D. Marks. 2018. Summary report Year 3 of 3: Habitat stewardship actions for pollinators in the Thompson-Okanagan and Similkameen Valleys, British Columbia, 2018. BC Ministry of Environment and Climate Change Strategy, Surrey, British Columbia. 65 pp. + 1 Appendix.

iNaturalist. 2020. Species records for Satyrium semiluna in Canada. California Academy of Sciences, San Francisco, California. Website: https://inaturalist.ca/observations?place_id=6712&taxon_id=230445 [accessed December 10, 2020]

iNaturalist. 2022. Species records for Satyrium semiluna in Canada. California Academy of Sciences, San Francisco, California. Website https://inaturalist.ca/observations?place_id=6712&taxon_id=230445 [accessed January 27, 2022]

Iverson, K., and A. Haney. 2012. Refined and updated ecosystem mapping for the south Okanagan and Lower Similkameen Valley. Internal report with BC Ministry of Environment, Penticton, British Columbia. 36 pp.

James, D.G., and D. Nunnallee. 2011. Life History of Cascadia Butterflies. Oregon State University Press, Corvallis, Oregon. 449 pp.

Johnson, C.G. Jr., and S.A. Simon. 1987. Plant associations of the Wallowa-Snake Province: Wallowa-Whitman National Forest. R6-ECOL-TP-255A-86. Baker, Oregon: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region, Wallowa-Whitman National Forest. 399 pp.

Klots, A.B. 1930. Diurnal Lepidoptera from Wyoming and Colorado. Distribution, life zone and habitat notes—new subspecies. Bulletin of the Brooklyn Entomological Society 25:147-170.

Knopp, D., L. Larkin, O. Dyer, and J. Heron. 2008. Half-moon Hairstreak Satyrium semiluna, South Okanagan inventory. Reported prepared for the Ecosystem Branch, Ministry of Environment, Vancouver, British Columbia. 45 pp.

Kohler, S. 1980. Checklist of Montana Butterflies (Rhopalocera). Journal of the Lepidopterists' Society 34:1-19. https://images.peabody.yale.edu/lepsoc/jls/1980s/1980/1980-34(1)1-Kohler.pdf [accessed January 4, 2022]

Kondla, N.G. 2003a. Preliminary field survey for the Sooty Hairstreak (Satyrium fuliginosum) in Waterton Lakes National Park. Report for Parks Canada. Report prepared for Parks Canada Agency. 17 pp.

Kondla, N.G. 2003b. The Sooty Hairstreak in British Columbia. Boreus 23:10-12.

Kondla, N.G. 2004. Waterton Lakes National Park Sooty Hairstreak survey, 2004. Report prepared for Parks Canada Agency. 24 pp.

Kondla, N.G. 2009. Waterton Lakes National Park 2009 Half-moon Hairstreak Project Report. Report prepared for Parks Canada Agency. 17 pp.

Kondla, N.G. 2012. Satyrium semiluna Survey Waterton Lakes National Park 2012. Report prepared for Parks Canada Agency. 17 pp.

Kondla, N.G., pers. comm. 2019–021. Email correspondence with Jennifer Heron. Lepidopterist, Calgary, Alberta.

Lacey, J.R., C.B. Marlow, and J.R. Lane. 1989. Influence of spotted knapweed (Centaurea maculosa) on surface runoff and sediment yield. Weed Technology 3:627-631.

Land Title and Survey Authority of British Columbia. 2022. myLTSA ParcelMap BC Search. Website: https://parcelmapbc.ltsa.ca/pmsspub/ [accessed January 26, 2022].

Layberry, R.A., P.W. Hall, and J.D. Lafontaine. 1998. The Butterflies of Canada. University of Toronto Press, Toronto, Ontario. 354 pp. + 32 pls.

Longcore, T., C.S. Lam, P. Kobernus, E. Polk, and J.P. Wilson. 2010. Extracting useful data from imperfect monitoring schemes: endangered butterflies at San Bruno Mountain, San Mateo County, California (1982-2000) and implications for habitat management. Journal of Insect Conservation 14:335-346.

Lyon, L.J., and P.F. Stickney. 1976. Early vegetal succession following large northern Rocky Mountain wildfires. In: Proceedings of the Montana Tall Timbers Fire Ecology Conference and Intermountain Fire Research Council Fire and Land Management Symposium; 1974 October 8-10; Missoula, Montana. No. 14. Tall Timbers Research Station, Tallahassee, Florida. Pp. 355-373.

MacDonald, Z., and J. Dupuis. pers. comm. 2022. Email correspondence with David McCorquodale. Entomology PhD student, University of Alberta, Edmonton, Alberta and Assistant Professor of Arthropod Systematics, University of Kentucky, Lexington, Kentucky.

Marks, D. pers. comm. 2022. Correspondence with David McCorquodale. BC Conservation Foundation, Surrey, British Columbia.

Master, L.L., D. Faber-Langendoen, R. Bittman, G.A. Hammerson, B. Heidel, L. Ramsay, K. Snow, A. Teucher, and A. Tomaino. 2012. NatureServe conservation status assessments: factors for evaluating species and ecosystems at risk. NatureServe, Arlington, Virginia. <https://www.natureserve.org/publications/natureserve-conservation-status-assessments-factors-evaluating-species-and-ecosystem> [accessed December 28, 2019]

Matthews, R.F. 1993. Lupinus sericeus. In: Fire Effects Information System, U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

Mattoon, S.O., and G.T. Austin. 1998. Review of Satyrium fuliginosum (W.H. Edwards) with the description of three new subspecies (Lepidoptera: Lycaenidae). Pp. 681-690 in Systematics of Western North American Butterflies, edited by T.C. Emmel. Mariposa Press, Gainesville, Florida. xxviii + 878 pp.

Nature Conservancy of Canada. 2020. Sage and Sparrow Conservation Area. https://www.natureconservancy.ca/en/where-we-work/british-columbia/featured-projects/south-okanagan-similkameen/sage-and-sparrow.html [accessed January 26, 2022].

NatureServe. 2020. NatureServe Explorer. [Online] Available: http://www.natureserve.org/explorer/ [accessed December 10, 2020].

Nicholson, A., E. Hamilton, W.L. Harper, and B.M. Wikeem. 1991. Bunchgrass Zone (Chapter 8). Pages 125–138 in Meidinger, D. and J. Pojar. Ecosystems of British Columbia Special Report Series 6, Ministry of Forests, Victoria, BC. Available at https://www.for.gov.bc.ca/hfd/pubs/docs/srs/srs06.pdf [accessed January 11, 2020].

Oetterich, S. 2018. Experimental Control of Spotted Knapweed (Centaurea stoebe) within Critical Habitat of the Endangered Half-moon Hairstreak Butterfly (Satyrium semiluna): A Pilot Study of Blakiston Fan, Waterton Lakes National Park, Alberta. Project Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in the Ecological Restoration Program Faculty of Environment Simon Fraser University, Burnaby, British Columbia. 79 pp. http://summit.sfu.ca/item/19103 [accessed November 30, 2021].

Okanagan and Similkameen Invasive Species Society. 2021. https://www.oiso.ca/species-category/terrestrial-plants/ [accessed May 25, 2021].

Open Standards. 2014. Threats taxonomy. http://cmp-openstandards.org/using-os/tools/threats-taxonomy/ [accessed December 10, 2020]

Parks Canada Agency. 2003. Terrestrial Ecozones of Canada. http://parkscanadahistory.com/publications/fact-sheets/eng/ecozones.pdf [accessed January 23, 2020].

Parks Canada Agency. 2016. Waterton Lakes National Park – Historical Grazing. Waterton Historical Vignettes - Parks Canada Stories and photographs of Waterton history. Grazing in Waterton - https://mywaterton.ca/do/waterton-historical-vignettes-parks-canada/85e1dd17-ef08-4461-9d6a-9888bc3e3865 [accessed December 10, 2020].

Parks Canada Agency. 2017. Let’s Talk About Climate Change: Mountain Region. Office of the Chief Ecosystem Scientist. Version 1.2. http://parkscanadahistory.com/publications/lets-talk-about-climate-change/5-mountain-e.pdf [accessed May 27, 2021].

Parks Canada Agency. 2019. Fire in Waterton Lakes National Park. https://www.pc.gc.ca/en/pn-np/ab/waterton/nature/environment/feu-fire [accessed December 10, 2020]

Pierce, N.E. 1987. The evolution and biogeography of associations between lycaenid butterflies and ants. Oxford Surveys in Evolutionary Biology 4:89-116.

Pollard, E. 1977. A method for assessing changes in the abundance of butterflies. Biological Conservation 12:115-134.

Province of British Columbia. 1996b. Park Act [RSBC 1996] c. 344. Queen’s Printer, Victoria, British Columbia. <https://www.bclaws.gov.bc.ca/civix/document/id/complete/statreg/96344_01> [accessed December 10, 2020]

Province of British Columbia. 2002. Forest and Range Practices Act [RSBC 2002] c. 69. Queen’s Printer, Victoria, British Columbia. <http://www.bclaws.ca/EPLibraries/bclaws_new/document/ID/freeside/00_02069_01> [accessed December 10, 2020]

Province of British Columbia. 2008. Oil and Gas Activities Act [SBC 2008] c. 36. Queen’s Printer, Victoria, British Columbia. <http://www.bclaws.ca/EPLibraries/bclaws_new/document/ID/freeside/00_08036_01> [accessed December 10, 2020]

Province of British Columbia. 2022. About the BC Wildfire Service: Statistics and Geospatial Data. Public safety and emergency services. Online resource. https://www2.gov.bc.ca/gov/content/safety/wildfire-status/about-bcws/wildfire-statistics [accessed January 26, 2022].

Pyle, R.M. 2002. The Butterflies of Cascadia, A Field Guide to All the Species of Washington, Oregon, and Surrounding Territories. Seattle Audubon Society, Seattle, Washington. 420 pp

Ramsay, L. 2012. Electronic database containing lepidoptera collections from Sage and Sparrow Conservation Area, Osoyoos. BC Conservation Data Centre. BC Ministry of Environment. Victoria, British Columbia.

Regional District of Okanagan-Similkameen. 2020. Environmental and Watercourse Development Permits. WDP, ESDP Brochure. Development Series. https://www.rdos.bc.ca/assets/planning/Forms/Brochure-EnvDPs.pdf [accessed January 26, 2022].

Regional District of Okanagan-Similkameen. 2022. RDOS Parcel Viewer. https://maps.rdos.bc.ca/Html5Viewer/?viewer=publicparcels [accessed January 26, 2022].

Ridenour, W.M. and R.M. Callaway. 2001. The relative importance of allelopathy in interference: the effects of an invasive weed on a native bunchgrass. Oecologia 126:444-450.

Sadler, K., pers. comm. 2012. Correspondence with J. Heron. Species at risk biologist, Canadian Wildlife Service, Delta, British Columbia.

Safford, K., pers. comm. 2019. Correspondence with J. Heron. Conservation Specialist, BC Parks and Protected Areas, Penticton, British Columbia.

Salafsky, N., D. Salzer, A.J. Stattersfield, C. Hilton-Taylor, R. Neugarten, S.H.M. Butchart, B. Collen, N. Cox, L.L. Master, S. O’Connor, and D. Wilkie. 2008. A standard lexicon for biodiversity conservation: unified classifications of threats and actions. Conservation Biology 22:897–911.

Sarell, M. 2013. Electronic database of observations from Sage and Sparrow Nature Conservancy of Canada properties. BC Conservation Data Centre, Victoria, British Columbia.

Schindler, D., and B. Donahue. 2012. The impacts of climate change on water in Alberta. Environmental Research and Studies Centre, University of Alberta, Edmonton. Web site: http://www.ualberta.ca/~ersc/water/climate.htm. [accessed: May 14, 2021]

Schmidt, C., pers. comm. 2019. Emails to Jennifer Heron. Entomologist. National Collection of Insects, Arachnids and Nematodes, Ottawa, Ontario.

Scott, D., B. Jones, and J. Konopek. 2007. Implications of climate and environmental change for nature-based tourism in the Canadian Rocky Mountains: A case study of Waterton Lakes National Park. Tourism Management 28:570-579.

Scott, J.A. 1986a. The Butterflies of North America. A Natural History and Field Guide. Stanford University Press, Stanford, California. 583 pp.

Scott, J.A. 1986b. Larval hostplant records for butterflies and skippers (mainly from western U.S.), with notes on their natural history. Papilio (New Series) 4:1-37.

Scott, J.A. 1992. Hostplant records for butterflies and skippers (mostly from Colorado) 1951-1991, with new life histories and notes on oviposition, immatures, and ecology. Papilio (New Series) 6:1-171.

Scott, L., D. St. John, D. Lalonde., and H. Baumbrough. 2007. Assessment report on Showy Phlox, Phlox speciosa, and Half-moon Hairstreak, Satyrium semiluna, in the White Lake Basin. Unpublished report prepared for Andrew Gray, National Research Council Canada, Dominion Radio Astrophysical Observatory, Penticton, British Columbia. 20 pp.

Shervill, D. 2010. Electronic database containing Satyrium semiluna (Half-moon Hairstreak) 2010 data. Canadian Wildlife Service, Delta, British Columbia.

SIRT (Southern Interior Invertebrates Recovery Team). 2008. Recovery strategy for Behr’s hairstreak (Satyrium behrii) in British Columbia. BC Ministry of Environment, Victoria, British Columbia. 16 pp.

Sissons, R. 2018. Status Update and Proposed Management Actions for the Endangered Half-moon Hairstreak (Satyrium semiluna) in Waterton Lakes National Park. Confidential unpublished report, Parks Canada Agency, Waterton Lakes National Park, Alberta.

Sissons, R., pers. comm. 2019 to 2022. Email and telephone communication with Jennifer Heron and Brenda Costanzo. Parks Canada Agency, Waterton Lakes, Alberta.

Sperling, F., pers. comm. 2022. Email correspondence with Jennifer Heron and David McCorquodale. Curator of entomology, University of Alberta, Edmonton, Alberta.

Spittlehouse, D.L. 2008. Climate Change, impacts, and adaptation scenarios: climate change and forest and range management in British Columbia. BC Ministry of Forests and Range, Research Branch, Victoria, British Columbia. Technical Report 045. https://www.for.gov.bc.ca/hfd/pubs/docs/Tr/Tr045.htm

St. John, D., pers. comm. 2019 to 2021. Email and telephone communication with Jennifer Heron. Private entomologist, Agassiz, British Columbia.

St. John, D., and L. Scott. 2008. Assessment Report on Half-moon Hairstreak Satyrium semiluna. Draft consultant report prepared for Ron Casorso, Dominion Radio Astrophysical Observatory. Penticton, British Columbia. 33 pp.

Stanford, R.E., and P.A. Opler. 1993. Atlas of western USA butterflies: including adjacent parts of Canada and Mexico. Unpubl. Report. Denver and Fort Collins, Colorado. 275 pp.

Tannas, S. 2014. Waterton Lakes National Park 2013 Survey of the Blakiston Fan. Prepared by Tannas Conservation Services Ltd for Parks Canada. Cremona, Alberta. 22 pp.

United States Department of Agriculture (USDA) and United States Forest Service (USFS). 2021. Fire Effects Information System (FEIS). Syntheses about fire ecology and fires regimes in the United States. https://www.feis-crs.org/feis/ [accessed November 30, 2021].

Walker, I.J. and R. Sydneysmith. 2008. British Columbia. pp. 329-386, in D.S. Lemmon, F.J. Warren, J. Lacroix, and E. Bush (eds.), From impacts to adaptation: Canada in a changing climate. Government of Canada, Ottawa, Ontario.

Warren, A.D. 2005. Lepidoptera of North America 6. Butterflies of Oregon: Their taxonomy, distribution, and biology. Contributions of the C.P. Gillette Museum of Arthropod Diversity, Colorado State University. 408 pp.

Weir, T.L., H.P. Bais, V.J. Stull, R.M. Callaway, G.C. Thelen, W.M. Ridenour, S. Bhamidi, F.R. Stermitz, and J.M. Vivanco. 2005. Oxalate contributes to the resistance of Gaillardia grandiflora and Lupinus sericeus to a phytotoxin produced by Centaurea maculosa. Planta 223:785-795.

Weston, M., pers. comm. 2019. Email correspondence and personal communication with Jennifer Heron. BC Parks and Protected Areas, Ministry of Environment, Penticton, British Columbia.

White, B., pers. comm. 2019. Email correspondence and personal communication with Jennifer Heron. South Okanagan-Similkameen Conservation Program (formerly), Penticton, British Columbia.

Biographical summary of report writer

Brenda Costanzo is the Senior Vegetation Specialist with the Conservation Science Section, British Columbia Ministry of Environment and Climate Change Strategy. For the past 18 years, Brenda has been involved in leading recovery teams and/or writing numerous recovery plans for plants at risk in British Columbia. Her background includes a M.Sc. from the University of Victoria in biology on the seed germination of two native shrubs from BC. She has written several status reports on rare vascular plants in BC.

Jennifer M. Heron is the provincial Invertebrate Conservation Specialist with the Conservation Science Section, British Columbia Ministry of Environment and Climate Change Strategy. She directs and manages the provincial approach to invertebrate conservation, including the development and implementation of provincial legislation, policy, procedures, and standards for the conservation and recovery of invertebrate species at risk, their habitats, and ecosystems, and measures to keep these species from becoming at risk. Her background includes a M.Sc. from the University of British Columbia on ant diversity in the south Okanagan region of BC. Her current interests include the native bees of western Canada and thermal spring invertebrates.

Online data sources and collections examined

• University of Calgary, Insects and Invertebrate Zoology Museum, Department of Biological Sciences, Calgary, AB (John Swann 2019)
• Northern Forestry Centre, Natural Resources Canada, Edmonton, AB (Greg Pohl 2019)
• Strickland Entomological Museum, Department of Biology, University of Alberta, Edmonton, AB (Danny Shepley 2019)
• Invertebrate Zoology, Royal Alberta Museum, Edmonton, AB (Matthias Buck 2019)
• Royal British Columbia Museum, Victoria, BC (Claudia Copley 2019)
• Spencer Entomological Collection, Beaty Biodiversity Museum, University of British Columbia, Vancouver, BC (Karen Needham 2019)
• Canadian National Collection of Insects, Arachnids and Nematodes, Agriculture and Agri-Food Canada, Ottawa, ON (online database 2019)
• INaturalist® (December 2021)
• BugGuide® (December 2021)
• eButterfly® (December 2021)

These additional collections were examined in the first COSEWIC (2006) status report and hold specimens of Half-moon Hairstreak:

• Crispin Guppy, Private Entomologist, Whitehorse, YT
• Gerald Hilchie, University of Alberta, Edmonton, AB
• Norbert Kondla, Private Entomologist, Calgary, AB
• Oregon State University, Corvallis, OR