Nuttall’s Sheep Moth (Hemileuca nuttalli): recovery strategy proposed 2023

Official title: Recovery Strategy for the Nuttall’s Sheep Moth (Hemileuca nuttalli) in Canada 2023

Species at Risk Act
Recovery Strategy Series

2023

Preface

The federal, provincial, and territorial government signatories under the Accord for the Protection of Species at Risk (1996)^{Footnote 2} agreed to establish complementary legislation and programs that provide for effective protection of species at risk throughout Canada. Under the Species at Risk Act (S.C. 2002, c.29) (SARA), the federal competent ministers are responsible for the preparation of recovery strategies for listed Extirpated, Endangered, and Threatened species and are required to report on progress within five years after the publication of the final document on the Species At Risk Public Registry.

The Minister of Environment and Climate Change is the competent minister under SARA for the Nuttall’s Sheep Moth and has prepared this recovery strategy, as per section 37 of SARA. To the extent possible, it has been prepared in cooperation with the Province of British Columbia, as per section 39(1) of SARA.

Success in the recovery of this species depends on the commitment and cooperation of many different constituencies that will be involved in implementing the directions set out in this strategy and will not be achieved by Environment and Climate Change Canada, or any other jurisdiction alone. All Canadians are invited to join in supporting and implementing this strategy for the benefit of Nuttall’s Sheep Moth and Canadian society as a whole.

This recovery strategy will be followed by one or more action plans that will provide information on recovery measures to be taken by Environment and Climate Change Canada and other jurisdictions and/or organizations involved in the conservation of the species. Implementation of this strategy is subject to appropriations, priorities, and budgetary constraints of the participating jurisdictions and organizations.

The recovery strategy sets the strategic direction to arrest or reverse the decline of the species, including identification of critical habitat to the extent possible. It provides all Canadians with information to help take action on species conservation. When critical habitat is identified, either in a recovery strategy or an action plan, SARA requires that critical habitat then be protected.

In the case of critical habitat identified for terrestrial species including migratory birds SARA requires that critical habitat identified in a federally protected area^{Footnote 3} be described in the Canada Gazette within 90 days after the recovery strategy or action plan that identified the critical habitat is included in the public registry. A prohibition against destruction of critical habitat under ss. 58(1) will apply 90 days after the description of the critical habitat is published in the Canada Gazette.

For critical habitat located on other federal lands, the competent minister must either make a statement on existing legal protection or make an order so that the prohibition against destruction of critical habitat applies.

If the critical habitat for a migratory bird is not within a federal protected area and is not on federal land, within the exclusive economic zone or on the continental shelf of Canada, the prohibition against destruction can only apply to those portions of the critical habitat that are habitat to which the Migratory Birds Convention Act, 1994 applies as per SARA ss. 58(5.1) and ss. 58(5.2).

For any part of critical habitat located on non-federal lands, if the competent minister forms the opinion that any portion of critical habitat is not protected by provisions in or measures under SARA or other Acts of Parliament, or the laws of the province or territory, SARA requires that the Minister recommend that the Governor in Council make an order to prohibit destruction of critical habitat. The discretion to protect critical habitat on non-federal lands that is not otherwise protected rests with the Governor in Council.

Acknowledgments

This recovery strategy was written by Jennifer Heron (B.C. Ministry of Environment and Climate Change Strategy [ENV]), Dawn Marks (ENV), and Eric Gross (Environment and Climate Change Canada – Canadian Wildlife Service – Pacific Region [ECCC-CWS-PAC]). Danielle Yu (ECCC-CWS-PAC) kindly prepared the maps. Lea Gelling (B.C. Conservation Data Centre [CDC]) and Katrina Stipec (CDC) provided occurrence information. Emily Cameron (CDC) provided advice on Antelope-brush ecological communities and current habitat loss. Jamie Leathem (B.C. Ministry of Forests, Lands, Natural Resource Operations and Rural Development [FLNRORD]), Josie Symonds (FLNRORD), Lora Neild (FLNRORD), Mark Weston (B.C. Parks), Sara Bunge (B.C. Parks), Kirk Safford (B.C. Parks), Brenda Costanzo (ENV), Bryn White, and Orville Dyer (ENV [retired]) provided updated information on Antelope-brush habitats and threats in the Okanagan. Updated information on threats at Haynes’ Lease Ecological Reserve and South Okanagan Wildlife Management Area was provided by Orville Dyer, Sarah Bunge, and Mark Weston. Scientific and technical review was provided by Thomas Calteau (ECCC-CWS- National Capital Region [ECCC-CWS-NCR]), Tiana Collins (ECCC – Wildlife Enforcement Directorate [ECCC-WED], Kimberly Dohms (ECCC-CWS-PAC), Christina Forbes (B.C. Ministry of Agriculture [AGRI]), Megan Harrison (ECCC-CWS-PAC), Jamie Leathem, Marie-Claude Leheutre (ECCC-CWS-NCR), Alanah Nasadyk (ENV), Andrea Shaw (AGRI), and Noella Trimble (ECCC-WED).

Executive summary

Nuttall’s Sheep Moth is a large (forewing length: 32-39 mm) and conspicuous day-flying moth with white to pale yellow forewings and hindwings that are bright yellow and framed by a pattern of thick black markings. Nuttall’s Sheep Moth ranges in North America from southern British Columbia (B.C.) to northern Arizona and New Mexico. Within Canada, the species is restricted to the Antelope-brush habitat within the south Okanagan Valley.

Nuttall’s Sheep Moth has an annual life cycle. The adult flight season is from August to mid-September. Adults are short-lived (less than a week) and do not feed. Females lay clusters of up to 50 eggs (potentially more) on the larval host plant, Antelope-brush (Purshia tridentata), during August and September. The eggs overwinter, and the larvae (caterpillars) hatch sometime in April and remain in clusters until the second or third instar. The caterpillars are also conspicuous, spiny, and black. The final instar is approximately 50 mm in length. The caterpillars feed on Antelope-brush until late May. At that time, they drop to the ground, burrow into the soft substrate, and form pupal cases. The species may overwinter two years if environmental conditions are not favourable for emergence.

A minimum of 100 observations of Nuttall’s Sheep Moth have been made in B.C. (1920 – 2002). Most were of caterpillars and recorded during April and May. These records are from four general areas, which are considered separate subpopulations: 1) Vaseux Lake, 2) North Osoyoos, 3) Oliver, and 4) Osoyoos. Subpopulations may consist of multiple sites. The most recent records for the species are from 2002 near Vaseux Lake and 1986 at Haynes’ Lease Ecological Reserve. The subpopulation at Vaseux Lake (#1) is considered extant. North Osoyoos (#2) is considered historical. Oliver (#3) and Osoyoos (#4) are of unknown status because they lack location details.

Nuttall’s Sheep Moth was assessed as Endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2015.The species is listed as Endangered on Schedule 1 of the Species at Risk Act (SARA). In B.C., Nuttall’s Sheep Moth is ranked S1 (critically imperiled) by the Conservation Data Centre and is on the provincial Red List. Recovery is biologically and technically feasible. Threats to the moth include the fragmentation, degradation, and conversion of Antelope-brush habitat from residential and commercial development, agriculture (mainly vineyards and orchards), and extensive wildfires in natural habitat.

The population and distribution objectives are to recover Nuttall’s Sheep Moth in Canada by improving redundancy within the population through (1) maintaining and/or restoring habitat to support known subpopulations (including any additional subpopulations that may be identified in the future), (2) maintaining and/or restoring connectivity between those subpopulations in Canada and to the larger population in the United States, and (3) addressing human-caused threats.

Short-term statements toward meeting population and distribution objectives are (1) to determine the feasibility of restoring subpopulations (i.e., one or more sites in the species’ area of occupancy), and (2) to identify suitable corridors of habitat connectivity within and between subpopulations and with source populations in the U.S.

Broad strategies to address threats to the survival and recovery of Nuttall’s Sheep Moth are presented below.

Critical habitat for Nuttall’s Sheep Moth has been identified to the extent possible with the best available information to address the population and distribution objectives. A schedule of studies outlines the activities required to complete the identification of critical habitat.

One or more action plans for Nuttall’s Sheep Moth will be posted on the Species at Risk Public Registry within ten years of the publication of this document.

Recovery feasibility summary

Based on the following four criteria that Environment and Climate Change Canada uses to establish recovery feasibility, there are unknowns regarding the feasibility of recovery of Nuttall’s Sheep Moth. In keeping with the precautionary principle, this recovery strategy has been prepared as per section 41(1) of SARA, as would be done when recovery is determined to be technically and biologically feasible. This recovery strategy addresses the unknowns surrounding the feasibility of recovery.

1. Individuals of the wildlife species that are capable of reproduction are available now or in the foreseeable future to sustain the population or improve its abundance.

Unknown. Nuttall’s Sheep Moth, at both the adult and larval (caterpillar) life stages, is rarely observed in Canada and the population trends, natural fluctuations or abundance, dispersal, and reproductive capability are unknown. Based on a lack of records for this bright, day-active and showy moth in Canada, the species seems to occur at low numbers within a habitat patch. One subpopulation of the moth (Vaseux Lake) is considered extant within an expansive area of Antelope-brush (Purshia tridentata) habitat. While the reproductive capabilities of the moth are unknown, it is assumed the quality and quantity of habitat is sufficient to sustain a subpopulation. It is unknown whether the subpopulation is stable due to a recent (2003) wildfire within part of this habitat. However, it is inferred that if the remaining area, extent, and quality of this habitat may still support a subpopulation, it remains extant. Detrimental changes in the quality of habitat include natural plant succession related to fire suppression, invasive species, or recreational activities that may degrade the habitat.

2. Sufficient suitable habitat is available to support the species or could be made available through habitat management or restoration.

Yes. Nuttall’s Sheep Moth requires Antelope-brush as its larval host plant, and there appears sufficient suitable Antelope-brush habitat the south Okanagan Valley. At present, there are approximately 2,433 ha of Antelope-brush / Needle-and-thread Grass habitat within the range of the species (Cameron pers. comm. 2020) as well as additional habitats with Antelope-brush where it is not the dominant shrub. While this habitat has decreased in area, extent, and quality from its original condition (approximately 9,800 ha in 1800; Iverson 2012), patches remain within the region, and some are protected on Crown or private conservation lands. It is assumed the species can maintain its population given sufficient habitat and host plant availability. Habitat management and restoration are likely necessary for all subpopulations.

3. The primary threats to the species or its habitat (including threats outside Canada) can be avoided or mitigated.

Unknown. Nuttall’s Sheep Moth is not known to habitually use the exact shrub or habitat patch year to year. Hemileuca species are strong fliers and, in general, use multiple habitat patches that include many larval host plants. Because the caterpillars consume host plants and require abundant, mature, and healthy host plants, they use multiple habitat patches, and, over time, the species will occupy portions of their habitat and use different host plant individuals year to year. Although the flight capabilities are unknown, other Hemileuca species have the ability to disperse up to 10 km in suitable habitat. With this information, the inferred primary threat to Nuttall’s Sheep Moth is the fragmentation, degradation, and conversion of Antelope-brush habitats from residential and commercial development and agriculture (mainly vineyards and orchards). Combined with this cumulative habitat loss is the increased risk to these ecosystems from wildfires as a result of fire suppression programs that have been in place for the past 150 years. The risk of fire has increased with the natural succession of native vegetation (e.g., conifer ingrowth) and the spread of non-native plants. Habitat degradation, caused by the spread of invasive plants, can be prevented by ongoing removal and restoration activities. However, it is unknown whether these mitigation options are viable in the long-term such that continued, active human intervention is not required. It is unknown to what extent habitat degradation caused by climate change can be mitigated or avoided.

4. Recovery techniques exist to achieve the population and distribution objectives or can be expected to be developed within a reasonable timeframe.

Yes. Habitat management or restoration actions exist and include: planting Antelope-brush within areas where wildfires have impacted the abundance of plants; removing invasive shrub plants that shade out and out-compete Antelope-brush and limit the ability of overwintering caterpillars to burrow into the soil during pupal formation through in-filling soil; and managing recreational activities (e.g., extensive foot traffic, dog walking, or illegal camping) to minimize soil compaction. The species appears to occur at low abundance within suitable habitats. Further understanding of abundance at extant sites and dispersal ability is required before supplementing wild populations with captive-bred individuals. Captive breeding may take place to gain knowledge regarding this species’ life history and reproductive capabilities. Development of additional recovery techniques to achieve the population and distribution objectives is expected within a reasonable time frame.

1. COSEWIC species assessment information

Date of assessment: November 2015

Common name (population): Nuttall’s Sheep Moth

Scientific name: Hemileuca nuttalli

COSEWIC status: Endangered

Reason for designation: This large, showy and conspicuous moth is restricted to Antelope-brush habitat in the Okanagan Valley of British Columbia. That habitat type has declined considerably in quality and extent in the past century and remains under threat due to continued conversion to viticulture, residential and commercial development, and impact of wildfires. This is a rare moth in Canada: very few have been observed since the first record in 1920. Potentially large fluctuations in the population size may affect its long-term viability.

Canadian occurrence: British Columbia

COSEWIC status history: Designated Endangered in November 2015.

* COSEWIC (Committee on the Status of Endangered Wildlife in Canada)

2. Species status information

The legal designation for Nuttall’s Sheep Moth on SARA Schedule 1 is Endangered (2023). The species is not listed in the category “Species at Risk” under the British Columbia (B.C.) Forest and Range Practices Act or Oil and Gas Activities Act, and there are no Identified Wildlife Species Accounts prepared under these acts. The species is not listed in the category “Species at Risk” under the B.C. Wildlife Act.

3. Species information

3.1 Species description

Nuttall’s Sheep Moth, Hemileuca nuttalli (Strecker 1875), is in the Family Saturniidae (wild or giant silk moths). The species grows through complete metamorphosis and has four distinct life stages: adult, egg, larva^{Footnote 4}, and pupa^{Footnote 5}. Additional information is further detailed in the COSEWIC (2015) status report and Tuskes et al. (1996).

The general life cycle of Nuttall’s Sheep Moth is one generation per year. The adult flight season is from August to September although it is possible adults could fly during late July. The lifespan of an adult moth is less than a week and is devoted solely to reproduction. During this time, males search for prospective mates by detecting female pheromone plumes. Females oviposit^{Footnote 6} clusters of eggs (50 - 200) together in rings around the stems of the larval host plant (Tuskes et al. 1996), which is Antelope-brush (Purshia tridentata) in Canada. The eggs overwinter and hatch beginning in April probably at the onset of Antelope-brush bud and leaf growth. Larvae (caterpillars) remain in tight clusters until their second or third instar at which point they disperse. The caterpillars feed on Antelope-brush until late May. At that time, they drop to the ground, burrow into it, and form pupal cases to undergo metamorphosis. The adults emerge in early August although individuals may be able to suspend their pupal development and overwinter as pupae to emerge the following August (Tuskes et al 1996).

Adult: Adults of both sexes are similar sizes with forewing lengths between 32 and 39 mm. The adults do not have functional mouthparts and do not feed during their August and September flight period. They are relatively large and conspicuous, yellow-bodied, day-flying moths with white, yellow, and black wing colouration (see Appendix A). White to pale yellow forewings and bright yellow hindwings are both marked with thick black lines and black veins near the black edges of the wings. Large, black discal spots are present on each wing. Two species of sheep moth, Hera/Sagebrush Buck Moth, H. hera (Harris 1841) and Western Sheep Moth, H. eglanterina (Boisduval 1852), overlap in range with Nuttall’s Sheep Moth in B.C. (Tuskes et al. 1996; BC CDC 2020). Refer to Appendix A for photographs of all species.

Egg: Eggs are oval and whitish-grey and are oviposited on host plant stems in late summer. They overwinter and hatch in April or May of the following year (COSEWIC 2015). Eggs have not been found in B.C.

Larva: Nuttall’s Sheep Moth caterpillars are conspicuous: black with stinging spines. First instar larvae were found near Vaseux Lake, B.C. on April 10, 1995 (COSEWIC 2015; BC CDC 2020). In other parts of the species’ range, caterpillars are active from May to June (Tuskes et al. 1996). Early instars exhibit gregarious behaviour. Third or fourth instar larvae disperse to feed separately. In B.C., wild caterpillars have been observed feeding only on Antelope-brush. Fully-grown caterpillars (over 50 mm long) enter leaf litter or burrow in soft soil to pupate in loose cocoons (Tuskes et al. 1996). Caterpillars have been found in B.C. and collected to rear through to adults. These adult specimens were deposited in the Royal B.C. Museum (Guppy pers. comm. 2020).

Pupa: The Nuttall’s Sheep Moth pupa is approximately 27 to 31 mm long and is a dark rusty-brown colour. Pupae have not been found in B.C. However, they were observed when collected caterpillars were reared through to adults (Guppy pers. comm. 2020). Adults may emerge either later that summer or the following year (COSEWIC 2015). In captivity, desert Hemileuca species have delayed emergence from their pupal cases 2 to 4 years, and it is possible this occurs in nature should environmental conditions be unfavourable for development or emergence (Tuskes et al. 1996). It is unknown if this occurs in B.C. (St. John 2010).

3.2 Species population and distribution

Globally, Nuttall’s Sheep Moth ranges in western North America, from southcentral B.C. through to northern Arizona and New Mexico (Figure 1; COSEWIC 2015). The approximate Canadian extent of occurrence is 71 km² (<1 % of the global range)

Figure 1. Approximate global range of Nuttall's Sheep Moth (from COSEWIC 2015). Information to create the distribution map was adapted from Peigler and Opler (1993) and Tuskes et al. (1996) using records from Crabo et al. (2012) and Opler et al. (2014).

The Canadian range of Nuttall’s Sheep Moth is restricted to the southernmost portion of the Okanagan Valley in B.C. where it is found in Antelope-brush grasslands (Figure 2). Records for the moth date from 1920 to 2002, and a minimum of 100 observations have been made in the province. Most of these have been caterpillars recorded in April and May.

Figure 2. Distribution of Nuttall's Sheep Moth in Canada. Sites are represented by their status (extant [square], historical [circle], and unknown [triangle]) and numbered by subpopulation (1 - Vaseux Lake; 2 - North Osoyoos; 3 - Oliver; 4 - Osoyoos).

Records for the moth are grouped into four subpopulations^{Footnote 7}: 1) Vaseux Lake, 2) North Osoyoos, 3) Oliver, and 4) Osoyoos. Subpopulations may consist of several sites (see Table 2). The status of the subpopulation at Vaseux Lake (#1) is extant^{Footnote 8}. North Osoyoos (#2) is historical^{Footnote 9}. Oliver (#3) and Osoyoos (#4) are unknown^{Footnote 10}.

1) Vaseux Lake (extant). Observations within the Vaseux Lake subpopulation are from two sites within 2 km of each other. There was a fire (human caused) in 2003, and Nuttall’s Sheep Moth has not been recorded since then. These habitats contained numerous mature (>50 years old) Antelope-brush shrubs that were lost in the fire. The subpopulation was surveyed for less than one day during the active period for caterpillars during the preparation of the COSEWIC (2015) status report. No additional systematic inventory has occurred at this site in the past ten years.

2) North Osoyoos (historical). One adult male Nuttall’s Sheep Moth was recorded from Haynes’ Lease Ecological Reserve in 1986. Wildfires occurred in 1989 and 1993 at the reserve (Roemer 1993) and significantly burned the mature Antelope-brush plants within this habitat. Further, vineyard development occurred adjacent to the north the reserve in 1994/1995 which would have reduced the area of available habitat. The species was not observed during targeted adult surveys in 2009 and caterpillar surveys in 2014 (COSEWIC 2015), and it has not been recorded incidentally during surveys for other species or by casual observers or naturalists who have visited the site. At present, mature Antelope-brush shrubs occur within the ecological reserve as well as within the adjacent wildlife management area and surrounding private properties.

3) Oliver (unknown) and 4) Osoyoos (unknown). Records for both Oliver (1965) and Osoyoos (1920 and 1953) are historical specimens with no associated location information beyond the town names. The Osoyoos records may have been within the habitat extent that included Haynes’ Lease Ecological Reserve and the North Osoyoos subpopulation (north end of Osoyoos Lake). These collection sites may have been converted since and rendered unusable due to extensive residential, commercial, or agricultural development of Antelope-brush habitats.

3.3 Needs of the Nuttall’s Sheep Moth

3.3.1 General habitat

Antelope-brush and associated ecological communities

In Canada, Nuttall’s Sheep Moth habitat includes ecological communities with the species’ larval host plant, Antelope-brush. Antelope-brush is found in the grassland, shrub-steppe, and open dry forests of the Okanagan Valley. Its range extends as far north as Penticton. The shrub has a separate population in the East Kootenays (e.g., the range is not contiguous with the Okanagan Valley) and is only connected through the United States (U.S.).

Records of Nuttall’s Sheep Moth in Canada, which can be accurately georeferenced, are from the Antelope-brush / Needle-and-Thread Grass (Purshia tridentata / Hesperostipa comata) ecological community (BC CDC 2020; Figure 3). Four additional ecological communities with Antelope-brush as a shrub component^{Footnote 11} occur within the moth’s range in the Okanagan Valley: Ponderosa Pine / Red Three-awn (Pinus ponderosa / Aristida purpurea var. longiseta), Ponderosa Pine / Smooth Sumac (Pinus ponderosa / Rhus glabra), Big Sagebrush / Bluebunch Wheatgrass - Arrowleaf Balsamroot (Artemisia tridentata / Pseudoroegneria spicata - Balsamorhiza sagittata), and Bluebunch Wheatgrass - Compact Selaginella (Pseudoroegneria spicata - Selaginella densa) (Cameron pers. comm. 2020; Table 3). The low detectability and abundance of Nuttall’s Sheep Moth and its larval host plant specificity suggest that the species may occur within these ecological communities and associated ecosystem mapping units. Antelope-brush grows throughout additional habitats, where the shrub is not the dominant species, including rocky outcrop habitat and the open Ponderosa Pine forests in the lower montane zone (Parish et al. 1996; Iverson et al. 2005; Iverson and Haney 2012; Klinkenberg 2014).

Figure 3. Antelope-brush / Needle-and-thread Grass habitat at Haynes’ Lease Ecological Reserve. The dark green shrubs are predominantly Antelope-brush. Photo J. Heron.

As of 2020, there are approximately 2,433 ha of the Antelope-brush / Needle-and-thread Grass ecological community within the range of Nuttall’s Sheep Moth in Canada (Cameron pers. comm. 2020) as well as additional habitats where Antelope-brush is not the dominant shrub (see Table 3). This ecological community has decreased in area, extent, and quality from its original condition of approximately 9,800 ha in 1800 (Iverson 2012). Patches remain within the region and some may be protected on Crown or private conservation lands.

3.3.2 Specific habitat functions

Nuttall’s Sheep Moth has four life stages: egg, larva, pupa, and adult. Limited information is available on the specific habitat features required of each life stage.

Oviposition and egg development habitat

Antelope-brush is the primary requirement for this life stage. Eggs are laid in rings around Antelope-brush stems during August and September.

It is not known whether female Nuttall’s Sheep Moth display a preference for a specific age class of Antelope-brush plants on which to oviposit. Mature plants (> 50 years) are expected to be selected rather than smaller, juvenile plants. Larger diameter plants provide more forage for the dependent caterpillars before they must move to another plant (i.e., developing caterpillars consume extensive amounts of plants during development). Site specific requirements for oviposition and egg development are presently unknown.

Larval habitat

Antelope-brush is the only species on which Nuttall’s Sheep Moth caterpillars have been observed feeding in Canada. In other parts of their range, caterpillars also have been recorded on snowberry (Symphoricarpos spp.), currants (Ribes spp.), and Desert Sweet (Chamaebatiaria millefolium) (Tuskes et al. 1996). The latter is not found in B.C. (COSEWIC 2015; BC CDC 2020). Larvae require enough host plant(s) to sustain them through each instar molt to pupation and adult emergence.

Unknown factors that also could influence larval habitat include caterpillar resting and basking sites, optimal activity temperatures, and refuge sites (i.e., from predators and weather).

Emergence habitat

Nuttall’s Sheep Moth pupa observations have not been recorded in B.C. Elsewhere, fully-grown caterpillars have been recorded pupating in leaf litter or burrows in soft soil (Tuskes et al. 1996; Davis 2014). In Utah, wild caterpillars were observed burrowing into sand along a roadside pullout to pupate. Captive-reared individuals burrowed into peat moss within a container and formed pupae within that space (Davis 2015). The depth Nuttall’s Sheep Moth caterpillars burrow and form pupal cases is unknown although all Hemileuca species are known to pupate in clumps of grass and/or surface debris, or, if available, will burrow 10 to 20 cm into loose soil (Tuskes et al. 1996). Surface debris includes the dry, dead, and friable leaf and needle litter that has fallen from trees, shrubs, and other plants as well as the mosses and bryophytes that form part of the cryptogamic^{Footnote 12} soil crust.

Perching, roosting, resting, and mating habitat

Perching, roosting, resting, and mating habitat used by adult Nuttall’s Sheep Moths in B.C. is unknown. Adults likely use shrubs or trees as night-time refuge and during inclement weather. In general, adult males move more widely through Antelope-brush habitats as they search for female pheromone plumes. Females are more sedentary, mainly because their bodies are heavier with eggs, and signal males through pheromone emission. Because they disperse and oviposit on Antelope-brush close to where they emerge, Antelope-brush habitat is important for adult functions.

3.4 Ecological roles

Adult Nuttall’s Sheep Moth do not feed during their short lifespan. Caterpillars of Hemileuca species have stinging spines that likely help them avoid predation from vertebrates. However, they remain exposed to dipteran and hymenopteran^{Footnote 13} parasitoids (Schowalter and Ring 2017). Parasitism of Nuttall’s Sheep Moth caterpillars in B.C. has not been studied.

3.5 Limiting factors

Limiting factors are generally not human-induced and include characteristics that make the species less likely to respond to recovery and conservation efforts. The main limiting factors for Nuttall’s Sheep Moth are speculative, but are likely a combination of the following:

• Small subpopulation size and abundance. Nuttall’s Sheep Moth is restricted to ecological communities with Antelope-brush. Small subpopulations in an isolated and fragmented habitat have an increased risk of local extirpation
• Dispersal ability. The dispersal ability of Nuttall’s Sheep Moth is unknown. Male sheep moths are considered strong fliers (Tuskes et al. 1996) and desert species have dispersed up to 1.6 km in a day (Collins 1974). Female adult moths emerge from pupation with fully developed unfertilized eggs, and, as a result, they have heavier bodies and may not fly far. In other Hemileuca, females generally do not move or oviposit far from where they emerge (within 10m; Bellows et al. 1984). Limited dispersal may reduce genetic mixing between subpopulations and lead to inbreeding depression and an increased chance of local extirpation
• Natural enemies. Predators, parasites, and parasitoids likely attack sheep moths at all life stages and could limit subpopulation abundance
• Larval host plant specificity. Nuttall’s Sheep Moth caterpillars are dependent on Antelope-brush to complete their life cycle. Antelope-brush is the only Purshia species in B.C. There is no information or evidence that other plant species are used as hosts in B.C
• Limited adult lifespan. The adult life span of Nuttall’s Sheep Moth is less than one week. This may limit mating opportunities and compound the effects of small subpopulation sizes

4. Threats

4.1 Threat assessment

The Nuttall’s Sheep Moth threat assessment is based on the IUCN-CMP (International Union for Conservation of Nature–Conservation Measures Partnership) unified threats classification system. Threats are defined as the proximate activities or processes that have caused, are causing, or may cause in the future the destruction, degradation, and/or impairment of the entity being assessed (population, species, community, or ecosystem) in the area of interest (global, national, or subnational). Limiting factors are not considered during this assessment process. For purposes of threat assessment, only present and future threats are considered. Historical threats, indirect or cumulative effects of the threats, or any other relevant information that would help understand the nature of the threats are presented in the Description of Threats section.

Threats to subpopulations #3 and #4 are not scored because the collection localities are unknown. However, if the threat is potentially applicable to unsurveyed Antelope-brush habitat within the general area of these subpopulations, the threat is discussed in the description of threats (Section 4.2).

4.2 Description of threats

Subpopulation specific threats to Nuttall’s Sheep Moth individuals and habitat are not well-documented. Land ownership and activities at a subpopulation greatly influence the type of threat imposed on the Antelope-brush habitats.

This threats assessment is based on the COSEWIC (2015) status report and is updated with new information. The updated threats assessment considers the habitat within a 4 km radius^{Footnote 14} around occurrences and additional local knowledge available on the habitat for each subpopulation.

The overall range-wide threat impact for Nuttall’s Sheep Moth in Canada is Medium^{Footnote 15}. The overall threat impact considers the cumulative impact of multiple threats. The primary threats to Nuttall’s Sheep Moth are the potential for wildfires that destroy Antelope-brush; the conversion of natural Antelope-brush habitats through residential, commercial, and agricultural development; and ecosystem modifications that result from the ingrowth of invasive plant species from fire suppression programs are changing the availability of loose friable soil available for caterpillar burrow and pupation sites. Details are discussed below under the threat headings. Threats with unknown impact are also described because of the uncertainty they impose upon the overall impact for the species.

Threat descriptions are provided in decreasing order of Threat impact levels, as per classification in Table 5 above.

IUCN-CMP # 2.1 Annual and perennial non-timber crops (low impact).

This threat is applicable to unprotected habitat within subpopulations #1 and #2. Agricultural land conversion and/or intensification (e.g., conversion of orchards to intensive viticulture) within suitable potential habitat through the removal of Antelope-brush host plants would affect potential subpopulations by reducing habitat connectivity for the species and limiting available habitat for dispersing individuals. Remnant Antelope-brush grows in steeper non-crop portions of agricultural areas in the Okanagan, and these small natural habitats may be important in connecting larger habitats by providing potential sites for oviposition and caterpillar development and/or adult resting or mating.

IUCN-CMP # 6.1 Recreational activities (low impact).

Recreational activities are ongoing within the habitat supporting subpopulations #1 and #2. The habitat at #1 includes Vaseux Provincial Park and Vaseux-Bighorn National Wildlife Area. Both areas offer recreational opportunities restricted to designated trails. At the portion of habitat within Haynes’ Lease Ecological Reserve in North Osoyoos (#2), recreational use is restricted to trails and there are no facilities, which tends to discourage extensive use. However, there is ongoing illegal camping, which results in litter, human waste, and chronic soil and habitat disturbance. There is hiking within #1, #2, and the potential habitat in #3 and #4. There is potential for all-terrain vehicle use in the potential habitat for #3 and #4.

IUCN-CMP # 9.3 Agricultural and forestry effluents (low impact).

This threat is potentially applicable to all subpopulations. Vaseux Lake (#1) and North Osoyoos (#2) are immediately adjacent to vineyards, many of which use pesticides. Pesticide drift is a potential threat to both caterpillars and adults. Drift of pesticides potentially could affect the larval host plant although the susceptibility of Antelope-brush to commonly used agrochemicals is unknown.

IUCN-CMP # 1.1 Housing and urban areas, 1.2 Commercial and industrial areas and 1.3 Tourism and recreation areas (unknown impacts).

Residential and commercial development is applicable to some habitat parcels that support subpopulations #1 and #2. Habitat is also within private conservation land (#1) and a provincial protected area (#2), which are not subject to these threats. However, there are pockets of Antelope-brush habitat within a 4 km radius surrounding these sites. The historical collection localities (for #3 and #4) are lacking. Nevertheless, development within unsurveyed suitable habitat through the removal of Antelope-brush host plants would affect potential subpopulations by reducing habitat connectivity for the species and limiting available habitat for dispersing individuals.

IUCN-CMP # 2.3 Livestock farming and ranching (unknown impact).

This threat is applicable to a portion of the Antelope-brush habitat within the South Okanagan Wildlife Management Area that supports subpopulation #2 (North Osoyoos). Cattle primarily graze this area in the late spring and fall. Antelope-brush is not preferred forage for cattle although in times of drought the plant may be grazed, and forage plants (e.g., bunch grasses and forbs) grow under and surrounding the Antelope-brush plants. Foraging livestock may inadvertently trample pupae or ingest or otherwise disturb eggs on the tips of Antelope-brush stems. Inappropriate grazing regimes affect Antelope-brush recruitment and seedling growth through trampling, urination, and defecation. Cattle trampling and resting also can impact pupal development sites.

IUCN-CMP # 3.2 Mining and quarrying (unknown impact).

There is a possibility of gravel extraction within properties adjacent to the Vaseux Lake (#1) habitats.

IUCN-CMP # 7.1 Fire and fire suppression (unknown impact).

The threat of wildfire is scored under this threat. Fire suppression is scored under 7.3, other ecosystem modifications. The threat of wildfire is applicable to all subpopulations (#1 – #4). Historically, fires may have been ignited by Indigenous peoples and by lightning weather events. Frequent, low-intensity wildfires once were likely more common throughout Antelope-brush habitats. Dry ground vegetative debris would have not built up due to fire control programs. Antelope-brush is a dry and highly flammable plant. There was an extensive wildfire within the habitat at subpopulation #1 in 2003 and at subpopulation #2 in 1993, and the mature Antelope-brush plants within these areas were burned. Nuttall’s Sheep Moth has not been recorded from these areas since the wildfires although there has been little systematic inventory and the effects on individuals or subpopulations are unknown.

IUCN-CMP # 7.3 Other ecosystem modifications (unknown impact).

Fire suppression within habitats that support subpopulations #1 and #2 has led to the spread in abundance and distribution of native (threat 8.1) and non-native (threat 8.2) invasive plants. Invasive plants are scored under threat 7.3 because the ingrowth of these plants modify the ecosystem and available habitat for moth pupation sites and Antelope-brush recruitment. The ingrowth of these plants has altered the natural fire regime in the Okanagan Valley and likely increased fire intensity and severity. Tree encroachment, in the absence of frequent fire, may have also reduced the size and extent of Antelope-brush plants at some sites, due to shading and competition. This threat is also applicable to potential habitat at subpopulations #3 and #4.

Adult Nuttall’s Sheep Moths do not feed, so the threat from non-native plants is only applicable to pupal development sites. Invasive non-native plants also may limit the ability of caterpillars to find suitable pupation sites. Caterpillars that are ready to pupate drop to the ground and burrow into the soft sandy soil and/or dry leaf litter to develop. Changes to soil chemistry from the growth of invasive non-native plants, and the ingrowth and spread of non-native plants that form a thick vegetative mat, may prevent caterpillars from accessing and burrowing into the otherwise soft friable soil. For example, monospecific stands of Sulphur Cinquefoil may prevent re-establishment of Antelope-brush plants after wildfires (SIIRT 2008) and limit caterpillar burrow and pupal development sites. This threat has not been studied.

Numerous non-native plant species are recorded throughout Antelope-brush ecosystems, and some appear to have little impact to the ecosystem (Symonds 2011). However, Sulphur Cinquefoil (Potentilla recta), Diffuse Knapweed (Centaurea diffusa), Cheatgrass (Bromus tectorum), and Dalmatian Toadflax (Linaria genistifolia ssp. dalmatica) adversely affect Antelope-brush habitats (Iverson 2012). These plants infill open sandy soils, prevent the establishment of Antelope-brush seeds, and limit the growth of Antelope-brush seedlings.

IUCN-CMP # 8.1 Invasive non-native/alien species and diseases (unknown impact).

Non-native invasive plants are discussed under Threat 7.3, other ecosystem modifications.

Compsilura concinnata (Diptera;Tachinidae) is a non-native parasitic fly introduced into eastern North America as biological control agent for European Gypsy Moth (Lymantria dispar). This fly may affect Hemileuca (Boettner et al. 2000), and may be present in B.C. (GBIF Secretariat 2019).

IUCN-CMP # 11.1 Habitat shifting and alteration, 11.2 droughts, 11.3 temperature extremes (unknown impacts)

Climate change is a potential but poorly understood threat to Nuttall’s Sheep Moth and its larval host plant. Increase in frequency and intensity of extreme and periodic climatic events could be a long-term threat to the small, isolated populations of Nuttall’s Sheep Moth.

IUCN-CMP # 3.3 Renewable energy (not applicable).

Adult Nuttall’s Sheep Moths have been collected at light traps and may be attracted to lights although light pollution is not considered a threat to the species.

IUCN-CMP # 5.1 Hunting and collecting terrestrial animals (not applicable).

Many of the B.C. specimens of Nuttall’s Sheep Moth have been reared from caterpillars collected in the field. The species rarely is observed in the Okanagan. It is difficult to detect and difficult to catch (i.e., male Hemileuca moths are strong fliers) (Collins 1974). Insect collection is not considered a threat to Nuttall’s Sheep Moth.

5. Population and distribution objectives

To recover Nuttall’s Sheep Moth in Canada by improving redundancy within the population through (1) maintaining and/or restoring habitat to support known subpopulations (including any additional subpopulations that may be identified in the future), (2) maintaining and/or restoring connectivity between those subpopulations in Canada and to the larger population in the United States, and (3) addressing human-caused threats.

Short-term statements toward meeting population and distribution objectives

1. To determine the feasibility of restoring subpopulations (i.e., one or more sites in the species’ area of occupancy)
2. To identify suitable corridors of habitat connectivity within and between subpopulations and with source populations in the U.S

Rationale

Nuttall’s Sheep Moth was assessed by COSEWIC as Endangered^{Footnote 16} in Canada on the basis of its small extent of occurrence (71 km²) and index of area of occupancy (20 km²) at less than five locations and the continuing declines in the area, extent, and quality of its habitat as well as the potential for large fluctuations in mature individuals. The survival characteristics that have been compromised are redundancy^{Footnote 17} and connectivity^{Footnote 18}. This species currently is recorded from one extant subpopulation, one historical, and two unknown. While there is limited information regarding the species’ historical distribution, the extent and quality of its restricted Antelope-brush habitat has been severely impacted by humans. These isolated subpopulations are particularly susceptible to extirpation events as a result of local human-caused threats, including fire. The threshold^{Footnote 19} separating designations of Endangered and Threatened include an index of area of occupancy (>500 km²) and/or more than five locations^{Footnote 20} without continuing declines in habitat. Given that the species was naturally precarious, the amount of irreversible change in habitat, and the unknown effectiveness of restoration of historical subpopulations, it is unlikely to improve the species’ condition to the extent necessary to achieve the threshold for downlisting. However, redundancy and connectivity could improve by maintaining and improving the amount and condition of the habitat to support known (extant and historical) subpopulations/sites and their connectivity, addressing additional human-caused threats, and restoring Nuttall’s Sheep Moth to historical sites through reintroduction. Thus, it is possible to improve the species’ survival condition meaningfully.

6. Broad strategies and general approaches to meet objectives

6.1 Actions already completed or currently underway

• Antelope-brush conservation measures have been included in Keeping Nature in Our Future: a biodiversity conservation strategy for the South Okanagan-Similkameen led by the South Okanagan Similkameen Conservation Program (2012)
• Portions of the habitat supporting the extant and historical subpopulations fall within Vaseux Lake Provincial Park, Haynes’ Lease Ecological Reserve (provincial), South Okanagan Wildlife Management Area (provincial), and Vaseux-Bighorn National Wildlife Area (federal)

6.2 Strategic direction for recovery

6.3 Narrative to support the recovery planning table

Population inventory and monitoring

The distribution and abundance of Nuttall’s Sheep Moth in Canada has great uncertainty due to low survey effort, so there is a need to develop a 10-year inventory and monitoring strategy that includes developing standard and repeatable survey and monitoring protocols.

There are approximately 2,433 ha of the Antelope-brush / Needle-and-thread Grass ecological community remaining within the south Okanagan (Cameron pers. comm. 2020), and these areas should be the focus for inventory. The additional four ecological communities where Nuttall’s Sheep Moth could occur comprise another 15,300 ha. Other ecological communities, including these four, that have Antelope-brush as a less dominant shrub should be included in the inventory because they also may be important for the moth. Surveys should prioritize habitats within a 10 km radius^{Footnote 21} surrounding all four subpopulations. Those at Oliver (#3) and Osoyoos (#4) will help to determine if these subpopulations are extant.

Surveys should be intensive and include two annual phases. Larval inventory should take place in April and May. Caterpillars are visible, relatively sedentary, and are focused on consuming Antelope-brush leaves during this period. The probability of detecting the species likely is higher at this life stage because of the limited mobility of caterpillars. Adult inventory should take place from late July through to early September during warm sunny days, between the hours of 10am and 4pm when adults would be most active and visible. Both inventories should be wandering transects through suitable habitat with course changes to survey Antelope-brush patches.

Habitat assessment, monitoring, and conservation

Concurrent with the population inventory and monitoring plan, data should be gathered to assess the scope, severity, and timing of threats applicable for the two most recently recorded subpopulations (#1 and #2). If additional subpopulations are recorded within the inventory radius of #3 or #4, this same threat information would be gathered. Specific needs within a 4 km radius surrounding subpopulations #1 and #2 are:

• to assess and mitigate future fire risk to the remaining Antelope-brush habitats
• to assess ongoing impacts from current land management activities on Antelope-brush habitats (e.g., how fire suppression activities impact the wildfire risk at these sites; how livestock grazing and/or native ungulate browsing could be impacting Antelope-brush regrowth)
• to engage landowners/managers within these areas in actions that recover Antelope-brush habitats on their properties including developing site prescriptions for planting Antelope-brush and mitigating threats to their regrowth; and
• to develop best management practices and/or stewardship plans for landowners/managers as needed

Conservation of habitat on provincial Crown land also will contribute to both species and habitat protection of Nuttall’s Sheep Moth. This includes working with the provincial government to recommend listing Nuttall’s Sheep Moth as a Species at Risk under the British Columbia Forest and Range Practices Act and Oil and Gas Activities Act. Additional beneficial work towards protecting the species includes working with provincial counterparts on integrating species management into provincial parks and protected areas planning documents at Haynes’ Lease Ecological Reserve; integrating considerations into management planning for the portions of the wildlife management area adjacent to Haynes’ Lease Ecological Reserve; continued landowner contact, stewardship, and public awareness on the conservation value of Antelope-brush habitats on private lands.

Research

There is limited information on the habitat requirements to sustain a subpopulation of Nuttall’s Sheep Moth. Research should be initiated to gain habitat and life history information, including: temperature and degree-day requirements for life stage development, mating, and oviposition; habitat use and daily activity patterns including mating and resting sites; pupal development sites and associated soil attributes; age, size, and health of Antelope-brush plants needed to sustain larval clusters and older caterpillars; and generation time. In addition, an understanding of dispersal and adult lifespan is important. This may be achieved through a capture-mark-recapture study.

Further research is needed to clarify factors that may limit Nuttall’s Sheep Moth subpopulations (e.g., life history parameters, parasitism, and predation). There is a need to develop a list of additional studies that address how limiting factors may affect moth subpopulations when cumulative threats are applied. Protocols for measuring and monitoring habitat and site-specific threats at sites where subpopulations are confirmed also need to be developed.

7. Critical habitat

Section 41(1)(c) of SARA requires that recovery strategies include an identification of the species’ critical habitat, to the extent possible, as well as examples of activities that are likely to result in its destruction.

Critical habitat for Nuttall’s Sheep Moth is identified in this recovery strategy to the extent possible based on the best available information. It is recognized that the critical habitat identified below is insufficient to achieve the population and distribution objectives for the species (Section 5). A schedule of studies (Section 7.2) has been developed to provide the information necessary to complete the identification of critical habitat that will be sufficient to meet population and distribution objectives. The identification of critical habitat will be updated when additional information becomes available.

7.1 Identification of the species’ critical habitat

Critical habitat for Nuttall’s Sheep Moth is identified for one extant subpopulation, Vaseux Lake, in southern British Columbia. The geospatial areas containing critical habitat for Nuttall’s Sheep Moth total 522.5 ha^{Footnote 22} (Figure 4). Within these geospatial areas, critical habitat is identified wherever the following biophysical attributes occur.

7.1.1 Biophysical attribute description

A description of the known biophysical features and attributes of the habitat that are required to support Nuttall’s Sheep Moth life-cycle processes (functions) in Canada is provided in Table 4. The biophysical features and attributes required by Nuttall’s Sheep Moth overlap geospatially across life history stages, in that they combine to provide an ecological context for the species at sites where it occurs. Therefore, within these polygons, only unsuitable areas that do not possess any of the features and attributes required by Nuttall’s Sheep Moth at any time are excluded from identification as critical habitat. Examples of these excluded areas include existing buildings, running surface of paved roadways, paved parking lots, cultivated areas with no Antelope-brush, and large waterbodies (lakes).

7.1.2 Information and methods used to identify critical habitat

The geospatial location of critical habitat is identified to encompass the areas required to support life history functions for eggs, larvae, pupae, and adults (described in Section 3.3, Table 4). All life history functions will occur within the areas that the species can disperse to successfully. Currently there is no information on the dispersal of Nuttall’s Sheep Moth, and there is little information about movement in other Hemileuca. In this case, NatureServe (2020) recommends 1 km as a conservative estimate of the inferred minimum extent of habitat use. Habitat use does not arbitrarily cease within contiguous suitable habitat patches. On this basis, most movements and life history functions of Nuttall’s Sheep Moth are estimated to occur within connected suitable habitat that begins within a 1 km distance from point occurrences. Because Nuttall’s Sheep Moth is reliant on Antelope-brush during its lifecycle in Canada, suitable habitat is selected based on all ecological communities that contain greater than a ten percent Antelope-brush component.

The detailed geospatial areas containing critical habitat for Nuttall’s Sheep Moth are based on the following methodology, which is sequentially applied to all verified extant occurrence records that have adequate location certainty (i.e., records must have been verified by a species expert, collected within the past 20 years [i.e., since 2000], and have a location uncertainty distance ≤ 150 m):

1. selecting each point occurrence and applying its associated location uncertainty distance (up to 150 m)
2. further applying a 1 km radial distance (in alignment with the inferred minimum extent of habitat use for saturniids^{Footnote 23} (NatureServe 2020))
3. selecting and retaining all suitable habitat polygons^{Footnote 24} that are within or intersect with the aggregate radius to encompass essential areas that are necessary to support life history functions
4. selecting and retaining all suitable habitat polygons that abut/are contiguous with polygons retained in step (3) (to account for continuity of habitat use and habitat connectivity within a subpopulation)

7.1.3 Geographic information

The geospatial areas containing critical habitat for Nuttall’s Sheep Moth are presented in Figure 4. The 1 km x 1 km UTM grid overlay (red outline) shown on this figure is part of a standardized national grid system used to indicate the general geographic area within which critical habitat is found.

Figure 4. Critical habitat for Nuttall’s Sheep Moth at Vaseux Lake, B.C., is represented by the shaded yellow polygons where the criteria and methodology set out in Section 7.1.2 are met. The 1 km x 1 km UTM grid overlay (red outline) shown on this figure is part of a standardized national grid system used to indicate the general geographic area within which critical habitat is found. Areas outside of the shaded polygons do not contain critical habitat.

7.2 Schedule of studies to identify critical habitat

The following schedule of studies (Table 7) outlines the activities required to complete the identification of critical habitat for Nuttall’s Sheep Moth.

7.3 Activities likely to result in the destruction of critical habitat

Understanding what constitutes destruction of critical habitat is necessary for the protection and management of critical habitat. Destruction is determined on a case-by-case basis. Destruction would result if part of the critical habitat were degraded, either permanently or temporarily, such that it would not serve its function when needed by the species to complete any part of its life cycle successfully. Destruction may result from single or multiple activities at one point in time or from the cumulative effects of one or more activities over time.

Activities, described in Table 8, include those likely to cause destruction of critical habitat for the species. Destructive activities are not limited to those listed.

8. Measuring progress

The performance indicators presented below provide a way to define and measure progress toward achieving the population and distribution objectives.

• The feasibility of restoring subpopulations/sites within the species’ area of occupancy has been determined; and
• Suitable corridors of habitat connectivity within and between subpopulations and with source populations in the U.S. have been identified

9. Statement on action plans

One or more action plans for the Nuttall’s Sheep Moth will be posted on the Species at Risk Public Registry within ten years of the posting of the final recovery strategy.

10. References

Bellows, T.S., J.C. Owens, and E.W. Huddleston. 1984. Flight activity and dispersal of range caterpillar moths Hemileuca oliviae (Lepidoptera: Saturniidae). Canadian Entomologist 116:247-254.

BC CDC (British Columbia Conservation Data Centre). 2020. BC Species and Ecosystems Explorer. B.C. Ministry of Environment and Climate Change Strategy. Victoria, B.C. Available from http://a100.gov.bc.ca/pub/eswp/ (Accessed September 21, 2020).

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(6):1796-1806.

Collins, M.M. 1974. The population dynamics of moths in the genus Hemileuca on Monitor Pass, California. M.A. Thesis, California State University, Hayward, California, 86 pp.

COSEWIC (Committee on the Status of Endangered Wildlife in Canada). 2015. COSEWIC assessment and status report on the Nuttall’s Sheep Moth Hemileuca nuttalli in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. X + 41 pp. Available: http://www.registrelep-sararegistry.gc.ca/default_e.cfm (Accessed September 17, 2020).

Crabo, L., P. Hammond, M. Peterson, J. Shepard, and R. Zack. 2012. Pacific Northwest Moths (http://pnwmoths.biol.wwu.edu/). Available: http://pnwmoths.biol.wwu.edu/browse/family-saturniidae/subfamily-hemileucinae/hemileuca/hemileuca-nuttalli/ (Accessed January 2015).

Davis, N. 2015. Nuttall’s Sheepmoth Hodges #7743: Photo Details. Wild Utah. Webpage. Available: https://www.wildutah.us/html/butterflies_moths/moths/h_m_hemileuca_nuttalli_immatures.html (Accessed September 9, 2020).

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).

IUCN (International Union for Conservation of Nature). 2001. IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K. (and subsequent updates). Available at IUCN Red List of Threatened Species https://www.iucnredlist.org/ (Accessed September 17, 2020).

Iverson, K. 2012. Ecosystem status report for Purshia tridentata / Heterostipa comata (Antelope-brush / needle-and-thread grass) in British Columbia. Unpublished report. B.C. Ministry of Environment, Conservation Data Centre, Victoria, BC. 35 pp.

Iverson, K., and A. Haney. 2012. Refined and Updated Ecosystem Mapping for the South Okanagan and Lower Similkameen Valley. Unpublished report. B.C. Ministry of Environment, Penticton. 36 pp.

Iverson, K., A. Haney, and M. Sarell. 2005. Updated Antelope-brush Mapping for the South Okanagan Valley. Unpublished report. B.C. Ministry of Environment, Penticton. 19 pp.

Klinkenberg, B. (ed.). 2014. Purshia tridentata – Antelope Brush. E-Flora BC: Electronic Atlas of the Plants of British Columbia [eflora.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver, B.C. Available: http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Purshia%20tridentata (Accessed November 8, 2020).

NatureServe. 2020. NatureServe Explorer 2.0: An online encyclopedia of life [web application]. NatureServe, Arlington, Virginia. Available: http://explorer.natureserve.org (Accessed: September 2020).

Opler, P.A., K. Lotts, and T. Naberhaus (coordinators). 2014. Butterflies and Moths of North America. Accessed as: Lotts, K., and T. Naberhaus. 2017. Butterflies and Moths of North America. Available: http://www.butterfliesandmoths.org/ (Accessed September 30, 2020).

Parish, R., R. Coupé, and D. Lloyd (eds.). 2018. Plants of Southern Interior British Columbia and the Inland Northwest. B.C. Ministry of Forests and Lone Pine Publishing. Vancouver, B.C. 463 pp.

Peigler, R.S., and P.A. Opler. 1993. Moths of Western North America. 1. Distribution of Saturniidae of Western North America. Gillette Museum Publications. Fort Collins, Colorado. 7 pp.

Roemer, H. 1993. The 1993 Fire at Hayne’s Lease Ecological Reserve. File report 6-2-1-91-56. B.C. Ministry of Environment. Available: http://www.env.gov.bc.ca/bcparks/eco_reserve/haynes_er/fire_1993.pdf (Accessed December 12, 2020).

Schowalter, T.D., and D.R. Ring. 2017. Biology and Management of the Buck Moth, Hemileuca maia (Lepidoptera: Saturniidae). Journal of Integrated Pest Management 8(1):1-5. Available: https://doi.org/10.1093/jipm/pmw017 (Accessed September 10, 2020).

SIIRT (Southern Interior Invertebrates Recovery Team). 2008. Recovery strategy for Behr’s Hairstreak (Satyrium behrii) in British Columbia. B.C. Ministry of Environment, Victoria, B.C.

South Okanagan Similkameen Conservation Program. 2012. Keeping Nature in Our Future: A Biodiversity Conservation Strategy for the South Okanagan Similkameen. South Okanagan Similkameen Conservation Program, Penticton, B.C. 98 pp. Available: https://soscp.org/wp-content/uploads/2017/08/KNOIF-2013-web-1.pdf (Accessed September 20, 2020).

St. John, D. 2010. An inventory strategy for Nuttall’s Buckmoth (Hemileuca nuttalli nuttalli (Strecker, 1875)) with commentary on Common Sheep Moth (Hemileuca eglanterina (Boisduval, 1852)) and Sagebrush Sheep Moth (Hemileuca hera hera (Harris, 1841)). Unpublished report. B.C. Ministry of Environment, Penticton Office, Penticton, B.C.

Symonds, J.E. 2011. Patterns and ecological consequences of exotic plant invasion in Canada’s endangered antelope-brush ecosystem. M.Sc. Thesis, University of British Columbia (Okanagan). 77 pp.

Tuskes, P.M., J.P. Tuttle, and M.M. Collins. 1996. The wild silk moths of North America: a natural history of the Saturniidae of the United States and Canada. Ithaca, NY and London: Cornell University Press. iv + 250 pp.

Wagner, D.L. 2005. Caterpillars of Eastern North America: A Guide to Identification and Natural History. Princeton Field Guides. Princeton University Press. Princeton, New Jersey. 512 pp.

11. Personal communication

Cameron, E. 2020. Vegetation Ecologist. British Columbia Conservation Data Centre, Victoria, B.C. Personal communication with Jennifer Heron and Eric Gross.

Guppy, C. 2020. Lepidopterist. Whitehorse, Yukon. Email and verbal correspondence with Jennifer Heron and Dawn Marks.

Appendix A: Photographs of Nuttall’s Sheep Moth and Co-occurring Sheep Moth Species in British Columbia

Nuttall’s Sheep Moth, Hemileuca nuttalli. Specimens from the Royal British Columbia Museum (RBCM), Victoria. Photo: J. Heron.

Hera Buck Moth, H. hera Specimen from the RBCM. Photo: J. Heron

Western Sheep Moth, H. eglanterina Specimen from the RBCM. Photo: C. Copley

Appendix B: Effects on the Environment and Other Species

A strategic environmental assessment (SEA) is conducted on all SARA recovery planning documents, in accordance with the Cabinet Directive on the Environmental Assessment of Policy, Plan and Program Proposals^{Footnote 29}. The purpose of a SEA is to incorporate environmental considerations into the development of public policies, plans, and program proposals to support environmentally sound decision-making and to evaluate whether the outcomes of a recovery planning document could affect any component of the environment or any of the Federal Sustainable Development Strategy’s^{Footnote 30} goals and targets.

Recovery planning is intended to benefit species at risk and biodiversity in general. However, it is recognized that strategies may also inadvertently lead to environmental effects beyond the intended benefits. The planning process based on national guidelines directly incorporates consideration of all environmental effects, with a particular focus on possible impacts upon non-target species or habitats. The results of the SEA are incorporated directly into the strategy itself, but also are summarized below in this statement.

This federal recovery strategy will benefit the environment by promoting the recovery of Nuttall’s Sheep Moth. The species is recorded from the Antelope-brush / Needle-and-thread Grass ecological community although it likely uses all ecological communities where Antelope-brush is present. This ecological community is globally and provincially imperiled (G2/S2) and Red-listed in B.C. (BC CDC 2020). Within the moth’s Canadian range, five ecological communities that have an Antelope-brush component comprise approximately 17,733 ha (Cameron pers. comm. 2020). Approximately 2,433 ha are Antelope-brush / Needle-and-thread Grass, which supports a high number of species at risk.

Antelope-brush habitat conservation will directly benefit Nuttall’s Sheep Moth and indirectly benefit additional species at risk in the Okanagan Valley. Conservation actions for this species at risk include: habitat restoration (e.g., planting Antelope-brush as larval host plants, invasive species removal), ongoing public education and awareness targeted to specific interest groups such as farmers, recreational users, and developers, and the protection/conservation of existing Antelope-brush habitat on provincial and federal lands. Multi-species approaches to conservation are recommended due to the high potential for numerous species at risk to co-occur within the same habitats.

Species at risk dependent on Antelope-brush ecosystems include at least 90 federally-listed species at risk and 56 provincially-listed species at risk (note some species are on both lists). Other SARA Schedule 1 species that may benefit from protective measures taken for Nuttall’s Sheep Moth include (but are not limited to): Behr’s Hairstreak (Satyrium behrii), Branched Phacelia (Phacelia ramosissima), Columbian Carpet Moss (Bryoerythrophyllum columbianum), Grand Coulee Owl-clover (Orthocarpus barbatus), Great Basin Gophersnake (Pituophis catenifer deserticola), Great Basin Spadefoot (Spea intermontana), Lewis's Woodpecker (Melanerpes lewis), Nuttall's Cottontail nuttallii subspecies (Sylvilagus nuttallii nuttallii), Pallid Bat (Antrozous pallidus), Scarlet Ammannia (Ammannia robusta), Short-rayed Alkali Aster (Symphyotrichum frondosum), Small-flowered Lipocarpha (Lipocarpha micrantha), Tiger Salamander (Ambystoma mavortium), Toothcup (Rotala ramosior), Wallis' Dark Saltflat Tiger Beetle (Cicindela parowana wallisi), Western Harvest Mouse megalotis subspecies (Reithrodontomys megalotis megalotis), Western Toad (Anaxyrus boreas), Western Rattlesnake (Crotalus oreganus), Western Yellow-bellied Racer (Coluber constrictor mormon), and Yellow-Scarab Hunter Wasp (Dielis pilipes).