Northern Bobwhite Colinus virginianus: COSEWIC rapid review of classification 2023

Official title: COSEWIC rapid review of classification on the Northern Bobwhite Colinus virginianus in Canada

Endangered

2023

COSEWIC assessment summary

Assessment summary – May 2023

Common name: Northern Bobwhite

Scientific name: Colinus virginianus

Status: Endangered

Reason for designation: This bird of open and semi-open habitats is widespread across the eastern United States, but range and numbers have declined dramatically from historical levels in Canada. With fewer than 250 birds remaining, all on Walpole Island in southwestern Ontario, the Canadian population may be close to extirpation. There have been no Christmas Bird Count records since 2001, and no eBird reports since 2014. However, occasional recent sightings by Walpole Island Indigenous community members indicate that a very small population likely still persists. Declines are attributed to deterioration of habitat quality owing to intensification of agriculture, and the loss of early succession woodland and semi-open habitats.

Occurrence: Ontario

Status history: Designated Endangered in April 1994. Status re-examined and confirmed in November 2003, May 2013, and May 2023.

COSEWIC rapid review of classification

Assessment summary

English name: Northern Bobwhite

French name: Colin de Virginie

Scientific name : Colinus virginianus

Status: Endangered

Reasons for designation (COSEWIC 2013): Owing to habitat loss, this grassland bird’s population has declined dramatically over historical levels and shows no sign of recovery. There is only one viable population remaining in Canada, located on Walpole Island, Ontario. The status of this species is complicated by the presence of introduced pen-reared birds whose genetic composition is believed to pose a threat to the remaining native population.

Preface

Northern Bobwhite (Colinus virginianus) formerly ranged across southern Ontario, but has almost disappeared in the wild from Canada, with a native population of fewer than 250 mature individuals confined to Walpole Island, in extreme southwestern Ontario (Wyshynski 2019). The overall status of the wild population has been confused in the past by the large number of captive-reared and released Northern Bobwhite, although such releases have not usually been successful in restoring populations (literature reviewed in Brennan et al. 2020), and non-native birds are no longer released on Walpole Island. Brennan (1991) documented similar declines of the species nearly range-wide across the eastern United States, beginning in the 1960s.

Walpole Island is thought to host the entire remaining wild stock of Northern Bobwhite in Canada (Risley 2007; COSEWIC 2013; ECCC 2018; Wyshynski 2019). Genetic analysis of Northern Bobwhite samples from Ontario supports the conclusion that birds occurring on the Walpole Island First Nation territory are native (Chabot 2014). However, all Northern Bobwhite reported from mainland Ontario in recent years are presumed to be of captive-reared origin (Risley 2007; Chabot 2014), including the scattered mainland records on eBird (2021) and iNaturalist (2021) in the last ten years.

In 2000, 92 male Northern Bobwhite were detected on Walpole Island First Nation territory during ground surveys for whistling males (MacIntyre 2002). Using a conservative extrapolation, MacIntyre (2002) estimated the population at 230 mature individuals. Five observers reported seeing Northern Bobwhite on Walpole Island in 2015, and seven others reported sightings in 2016. While most reports were of 1–-2 birds, three coveys were reported in 2015 of five, nine, and 30 birds, and another three in 2016 of approximately 12, 20, and 30 birds (Jacobs and Johnson 2016; C. Jacobs pers. comm. 2016 cited in Wyshynski 2019). Wyshynski (2019) reported that recent local community knowledge confirmed the persistence of Northern Bobwhite on Walpole Island First Nation up to 2016, and there have been occasional sightings by Indigenous community members since then (Jacobs pers. comm. 2021).

The first Ontario Breeding Bird Atlas (1981–1985) reported Northern Bobwhite on 27% of 27 point counts in the 10x10 km square that contains Walpole Island, but on only 8% of 27 point counts in the second atlas (2001–2005; Ontario Breeding Bird Atlas Database 2022). The third atlas reported male Northern Bobwhite calling in that square during the first season of observations in 2021, but breeding has not been confirmed (Birds Canada NatureCounts Database; Bumelis pers. comm. 2022).

The last report of Northern Bobwhite on Walpole Island in eBird was in 2014 (eBird 2021), and none of the 107 eBird checklists submitted for Walpole Island from 2015 to 2021 reported this species (eBird 2021). The Wallaceburg Christmas Bird Count, which covers most of the suitable habitat on Walpole Island (Risley 2007), shows a declining trend from 1991–1992 until 2000–2001, with no Northern Bobwhite records from 2001 to 2020 (National Audubon Society 2020).

Wyshynski (2019) concludes that the population has declined significantly from the estimate reported in MacIntyre (2002), and Jacobs and Johnson (2016) indicate that local knowledge also demonstrates appreciable declines.

The evidence from the Breeding Bird Atlas projects, local Indigenous knowledge, and eBird support the inference that there has been a marked continuing population decline, and Northern Bobwhite likely only persists in very small numbers on Walpole Island.

Walpole Island Heritage Centre and the Walpole Island Land Trust have undertaken the restoration and protection of tallgrass prairie and savannah sites used by Northern Bobwhite in the past (Jacobs and Johnson 2016), although it is uncertain whether there is an appropriate mixture of early successional wooded areas and open and semi‑open habitats to maintain this species (Wyshynski 2019).

Current status

Endangered (2013)

Reasons for designation (COSEWIC 2013)

Owing to habitat loss, this grassland bird’s population has declined dramatically from historical levels and shows no sign of recovery. There is only one viable population remaining in Canada, located on Walpole Island, Ontario. The status of this species is complicated by the presence of introduced pen-reared birds whose genetic composition is believed to pose a threat to the remaining native population.

Updated map

Not required

Explanation

Map not required. See maps in previous assessment (COSEWIC 2013) and recovery strategies (ECCC 2018; Wyshynski 2019).

Technical summary

Colinus virginianus

Northern Bobwhite

Colin de Virginie

Range of occurrence in Canada: Ontario

Demographic information

Generation time (usually average age of parents in the population):

2.3 years. Based on generation time in Bird et al. 2020.

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

Yes, inferred continuing decline, although no recent survey data are available. Based on extremely limited number of sightings in recent years, with no eBird records since 2015.

Estimated percent of continuing decline in total number of mature individuals within [5 years or 2 generations, whichever is longer up to a maximum of 100 years]:

Unknown. Insufficient data are available to estimate rate of inferred continuing decline.

[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over the last [10 years, or 3 generations, whichever is longer up to a maximum of 100 years]:

Unknown. Insufficient data are available to estimate rate of reduction.

[Projected or suspected] percent [reduction or increase] in total number of mature individuals over the next [10 years, or 3 generations, whichever is longer up to a maximum of 100 years]:

Unknown. Insufficient data are available to project future trends.

[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over any period [10 years, or 3 generations, whichever is longer up to a maximum of 100 years], including both the past and the future:

Unknown. Insufficient data are available to estimate recent population trends and project future trends.

Are the causes of the decline clearly understood?

Yes. Likely a combination of habitat loss and other threats (ECCC 2018; Wyshynski 2019)

Have the causes of the decline ceased?

No. Although some tallgrass prairie and savannah sites have been restored on Walpole Island (Jacobs and Johnson 2016), it is uncertain whether there is an appropriate mix of early successional woodland and open/semi-open habitats to sustain Northern Bobwhite numbers (Wyshynski 2019). Habitat conditions in the historical range in mainland Ontario have continued to decline.

Are the causes of the decline clearly reversible?

No

Are there extreme fluctuations in number of mature individuals:

No

Extent and occupancy information

Estimated extent of occurrence (EOO):

<72 km². As estimated EOO of Walpole Island is smaller than maximum IAO, the value for IAO is used here for EOO (IUCN 2022).

Index of area of occupancy (IAO), reported as 2x2 km grid value:

<72 km². Maximum IAO of 72 km² calculated on basis of 2x2 km grid squares with suitable upland habitat for Northern Bobwhite mapped on Walpole Island (Burrell pers. comm. 2022).

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. Unknown. Remaining population is at a single site that may be smaller than required to support a viable population
2. Possibly. Long-distance dispersal is rare in this species, with dispersal range usually < 1.6 km

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

One. The entire Canadian population breeds on Walpole Island, so the whole population would be affected by one threat such as habitat loss and fragmentation.

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

Possibly. Insufficient recent observations available to determine decline in EOO.

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

Yes. Inferred decline in IAO based on observed decline in availability of suitable habitat and inferred decline in number of individuals.

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

Not applicable. No subpopulations

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

Not applicable. Only one location, based on threat of habitat loss and fragmentation due to agricultural expansion and intensification.

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

Yes.Restoration activities have improved habitat quality in small areas of Walpole Island and adjacent Lambton County, but habitat extent and quality continue to decline overall due to intensification of agriculture and loss of cover due to burning.

Are there extreme fluctuations in number of subpopulations?

No. No subpopulations.

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 on website for more information on this term.

Number of mature individuals

N Mature Individuals (give plausible ranges) total (no subpopulations):

<<250, high probability of <50, and perhaps close to extirpation.

Notes on individual estimates total (no subpopulations):

Canadian population may be close to extirpation on Walpole Island, with no Christmas Bird Count records since 2001, no eBird reports since 2014, and very few sightings since 2016.

Quantitative analysis

Is the probability of extinction in the wild at least [20% within 20 years or 5 generations whichever is longer up to a maximum of 100 years, or 10% within 100 years]?

Unknown. Analysis not conducted.

Threats and limiting factors

Was a threats calculator completed for this species?

Threats assessments included in provincial (Wyshynski 2019) and national (ECCC 2018) recovery strategies.

The main threats to Northern Bobwhite in Canada, in decreasing order of impact, are (Wyshynski 2019):

• habitat loss and fragmentation, mainly through agricultural expansion and intensification, residential development, and invasion by European Common Reed (Phragmites australis)
• predation
• indiscriminate burning
• release of non-native, captive-reared Northern Bobwhites (no longer released on Walpole Island)
• herbicide/pesticide use; and
• potentially European Fire Ant (Myrmica rubra), feral cats, and feral pigs

What additional limiting factors are relevant? High site fidelity (COSEWIC 2013) which limits movement among alternate areas.

Rescue effect (natural immigration from outside Canada)

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

Declining. S2 (Imperiled) in Michigan, S4 (Apparently Secure) in New York, and S5 (Secure) in Ohio. BBS results indicate declines every year from 1987 to 2019.

Is immigration known or possible?

Possible, but unlikely. Northern Bobwhite does not disperse widely compared with other bird species (NatureServe 2022). Chabot (2014) found very little historical gene flow with Michigan birds.

Would immigrants be adapted to survive in Canada?

Possible, but unlikely. Translocated individuals often fail to become established (Brennan et al. 2020).

Is there sufficient habitat for immigrants in Canada?

No. Habitat is thought to be limiting in Canada.

Are conditions deteriorating in Canada?⁺

Yes. Habitat quality is declining due to intensification of agriculture.

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

Yes. Declining in most adjacent U.S. states, likely due to similar declines in habitat quality

Is the Canadian population considered to be a sink?⁺

Unknown

Is rescue from outside populations likely?

No. Numbers declining in adjacent U.S. states; habitat quality declining in Canada; and long-distance dispersal is rare.

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

Occurrence data sensitivity

Are occurrence data of this species sensitive?

No

Status history

COSEWIC: Designated Endangered in April 1994. Status re-examined and confirmed in November 2003, May 2013, and May 2023.

Status and reasons for designation

Status: Endangered

Alpha-numeric codes: B1ab(ii,iii,v)+2ab(ii,iii,v); C2a(i,ii); D1

Reasons for designation (2023): This bird of open and semi-open habitats is widespread across the eastern United States, but range and numbers have declined dramatically from historical levels in Canada. With fewer than 250 birds remaining, all on Walpole Island in southwestern Ontario, the Canadian population may be close to extirpation. There have been no Christmas Bird Count records since 2001, and no eBird reports since 2014. However, occasional recent sightings by Walpole Island Indigenous community members indicate that a very small population likely still persists. Declines are attributed to deterioration of habitat quality owing to intensification of agriculture, and the loss of early succession woodland and semi-open habitats.

Applicability of criteria

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

Not applicable. There are insufficient data to calculate rate of population decline, and major declines likely occurred > 10 years ago.

Criterion B (Small distribution range and decline or fluctuation.

Meets Endangered, B1ab(ii,iii,v)+2ab(ii,iii,v), as EOO is < 5,000 km²; IAO is < 500 km²; the population occurs at one location; and there is a continuing decline inferred in the index of area of occupancy, observed in the quality of habitat, and inferred in the number of mature individuals.

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

Meets Endangered, C2a(i,ii), as the total population is estimated to be < 250 mature individuals, with an inferred decline in numbers that is liable to continue; and the only subpopulation having < 250 mature individuals and 100% of all mature individuals.

Criterion D (Very small or restricted population):

Meets Endangered, D1, because the population is estimated to have < 250 mature individuals.

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

Acknowledgements

Funding for the preparation of this report was provided by Environment and Climate Change Canada. Richard Elliot, Co-chair of the COSEWIC Birds Specialist Sub-committee (SSC), and SSC members Pete Davidson, Mike Burrell, and Liana Zanette, provided helpful feedback in the preparation of this report. Mike Burrell also assisted in contacting Walpole Island First Nation Northern experts, assessing Ontario occurrence records, and estimating IAO. Clint Jacobs from the Walpole Island Heritage Centre provided valuable Indigenous knowledge from the Walpole Island First Nation. The authorities listed below provided valuable information and/or advice.

Authorities contacted

• Bumelis, Kaelyn. Ontario Breeding Bird Atlas Assistant Coordinator, Birds Canada, Port Rowan, Ontario
• Burrell, Mike. Provincial Zoologist – Vertebrates, Ontario Natural Heritage Information Centre, Ministry of Northern Development, Mines, Natural Resources and Forestry, Peterborough, Ontario
• Jacobs, Clint. Walpole Island Heritage Centre, Walpole Island First Nation, Walpole Island, Ontario
• Jardine, Catherine. Data Analyst, Birds Canada, Port Rowan, Ontario
• Jones, Colin. Provincial Zoologist - Arthropods, Ontario Natural Heritage Information Centre, Ministry of Northern Development, Mines, Natural Resources and Forestry, Peterborough, Ontario, and Member of COSEWIC for Ontario

Information sources

Bird, J.P., R. Martin, H.R. Akçakaya, J. Gilroy, I.J. Burfield, S.T. Garnett, A. Symes, J. Taylor, Ç.H. Şekercioğlu, and S.H.M. Butchart. 2020. Generation lengths of the world’s birds and their implications for extinction risk. Conservation Biology 34:1252–1261.

Birds Canada NatureCounts Database. Website: https://www.birdscanada.org/naturecounts/onatlas/squaresummaryform.jsp?squareID=17TLH71 [accessed February 2022].

Brennan, L.A. 1991. How can we reverse the Northern Bobwhite population decline. Wilson Bulletin 19:544-555.

Brennan, L.A., F. Hernandez, and D. Williford. 2020. Northern Bobwhite (Colinus virginianus), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, New York. Website: https://doi.org/10.2173/bow.norbob.01 [accessed February 2021].

Bumelis, K., pers. comm. 2022 Email correspondence to D.F. Fraser. February 2020. Ontario Breeding Bird Atlas Assistant Coordinator, Birds Canada, Port Rowan, Ontario.

Burrell, M., pers. comm. 2022. Email correspondence to Richard Elliot. February 2022. Provincial Zoologist – Vertebrates, Ontario Natural Heritage Information Centre, Ministry of Northern Development, Mines, Natural Resources and Forestry, Peterborough, Ontario.

Chabot, A. 2014. Development of genomic tools for population management and risk assessment for Northern Bobwhite in Ontario. Unpublished report for Canadian Wildlife Service – Ontario. Arden, Ontario. 30 pp.

COSEWIC. 2013. COSEWIC status appraisal summary on the Northern Bobwhite Colinus virginianus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xiii pp. https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/cosewic-assessments-status-reports/northern-bobwhite-appraisal-summary-2013.html.

eBird. 2021. eBird: An online database of bird distribution and abundance. eBird, Ithaca, New York. Website: http://www.ebird.org [accessed February 2021].

Environment and Climate Change Canada. 2018. Recovery strategy for the Northern Bobwhite (Colinus virginianus) in Canada. Species at Risk Act Recovery Strategy Series. Environment and Climate Change Canada, Ottawa. ix + 37 pp https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/recovery-strategies/northern-bobwhite-2018.html[accessed February 2022].

iNaturalist. 2021. iNaturalist. Website: https://www.inaturalist.org [accessed February 2021].

IUCN Standards and Petitions Committee. 2022. Guidelines for Using the IUCN Red List Categories and Criteria. Version 15. Prepared by the Standards and Petitions Committee. Website: https://www.iucnredlist.org/documents/RedListGuidelines.pdf [accessed February 2022].

Jacobs, C., pers. comm. 2021. Email correspondence to Mike Burrell. July 2021. Walpole Island Heritage Centre, Walpole Island First Nation, Walpole Island, Ontario.

Jacobs, C., and K. Johnson. 2016. Northern Bobwhite on Walpole Island First Nation. Unpublished report to Canadian Wildlife Service – Ontario. Walpole Island Heritage Centre, Walpole Island First Nation. 15 pp.

James, R.D., and R. Cannings. 2003. COSEWIC assessment and update status report on the Northern Bobwhite Colinus virginianus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 20 pp.

MacIntyre, K. 2002. A technical report outlining the status of Northern Bobwhite, Colinus virginianus, in the Aylmer District. Ontario Ministry of Natural Resources, Aylmer, Ontario. 14 pp.

National Audubon Society. 2020. The Christmas Bird Count Historical Results [online]. Website: http://www.christmasbirdcount.org [accessed February 2022].

NatureServe. 2022. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Website: http://www.natureserve.org/explorer [accessed February 2022].

Ontario Breeding Bird Atlas Database. 2022. Summary statistics for square 17LH71. Website: https://www.birdsontario.org/jsp/summaryform.jsp?squareID=17LH71&sumtype=1st [accessed February 2022].

Page, A.M., and M.J. Austen. 1994. Status report on the Northern Bobwhite Colinus virginianus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 34 pp.

Risley, C. 2007. Northern Bobwhite Colinus virginianus. Pp. 134-135 in M.D. Cadman, D.A. Sutherland, G.G. Beck, D. Lepage, and A.R. Couturier (eds.). Atlas of the Breeding Birds of Ontario, 2001-2005. Bird Studies Canada, Environment Canada, Ontario Field Ornithologists, Ontario Ministry of Natural Resources, and Ontario Nature, Toronto, Ontario. 706 pp.

Wyshynski, S.A. 2019. Recovery Strategy for the Northern Bobwhite (Colinus virginianus) in Ontario. Ontario Recovery Strategy Series. Prepared by the Ministry of the Environment, Conservation and Parks, Peterborough, Ontario. v +11 pp. + Appendix. Adoption of the Recovery Strategy for (Colinus virginianus) in Canada (Environment Canada 2018). Website: https://www.ontario.ca/page/northern-bobwhite-recovery-strategy [accessed February 2021].

Writer of rapid review of classification

• David F. Fraser, Non-government Science Member of COSEWIC: February 2022

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.