Part 1 COSSARO candidate species at risk evaluation form – May 2010

Eskimo Curlew (Numenius borealis)

Current designations:

GRANK – GH (NatureServe 2010)
NRANK Canada – NHB (NatureServe 2010)
COSEWIC – Endangered (November 2009)
SARA – Endangered, Schedule 1
General Status Canada – At Risk (2005)
ESA 2007 – Endangered
SRANK – SHN (NatureServe 2010)
General Status Ontario – At Risk (2005)

Distribution and status outside Ontario:

"Formerly a common to abundant migrant; in fall, migrating from the western Northwest Territories east to the coast of Labrador, and then essentially non-stop south to wintering areas in central Argentina and south. In spring migration, the species followed a different route up the coast of South America, through Central America, and then north through the central-western U.S. states and the Canadian prairie provinces to the Northwest Territories. While the breeding range of Eskimo Curlew may have been more extensive, only two nesting areas have ever been documented, both in the Northwest Territories, Canada." (Sutherland 2000). Although credible sightings of the species have been made in recent decades there have been no fully substantiated records since 1963, when a bird was collected in Barbados (COSEWIC 2009).

Eligibility criteria

Native status

✔ Yes. Known to have been a regular common transient in fall migration along the Hudson and upper James Bay coasts, and at least of irregular occurrence in spring in southern Ontario (Sutherland 2000). Eskimo Curlew has never bred in Ontario.

Taxonomic distinctness

✔ Yes. Considered a valid species in all recent taxonomic treatments, though in the past some authors have considered it conspecific with the Asiatic Little Curlew, Numenius minutus (e.g. AOU 1983). The close physical similarity between the Eskimo Curlew and the Little Curlew is a confounding factor in the authentication of sight records of Eskimo Curlew (Sutherland 2000). No infraspecific taxa have been described.

Designatable units

Only ever known in Ontario as a migrant where it was once a regular common transient in fall migration along the Hudson and upper James Bay coasts, and at least of irregular occurrence in spring in southern Ontario (Sutherland 2000). Since only a migrant in Ontario there is no need to assess as more than one unit in the province.

Priority-setting criteria

Recent arrival

✔ No. Bone fragments found in an archaeological dig at Fort Albany and reported to have been deposited in the period 1679-1721 (Baldwin 1967) constitute the earliest positive record for the species in Canada; and specimens collected at Fort Albany, Ontario, were later used by Forster to formally describe the species in 1772 (Gollop et al. 1986) (Sutherland 2000).

Non-resident

✔ No. Occurred formerly as a transient in migration, however there have been no documented reports for the province since 1976. Eskimo Curlew has never been recorded breeding any closer to Ontario than the Bathurst Peninsula, Northwest Territories. It occurs or occurred in Ontario only as a transient in migration. (Sutherland 2000, COSEWIC 2009)

Primary criteria (rarity and declines)

  1. Global rank

    ✔ Endangered. GH.

  2. Global decline

    ✔ Endangered. Has undergone a global, noncyclical population decline of ≥50% from historic times to the present.

  3. Northeastern North America ranks

    ✔ Endangered. Highly ranked (S1, S2, SH or SX) in 16 of 16 northeastern jurisdictions in which it occurs natively and is not considered accidental (100%). Considered accidental in two other jurisdictions (OH, RI). See Appendix 1.

  4. Northeastern North America decline

    ✔ Endangered. Has undergone a global, noncyclical population decline of ≥50% from historic times to the present in northeastern North America.

  5. Ontario occurrences

    ✔ Endangered. There are no identifiable Element Occurrences in Ontario as the species is only a transient in migration (Sutherland 2000). There are no documented Ontario reports since 1976.

  6. Ontario decline

    ✔ Endangered. Known to have been a regular, common transient in fall migration along the Hudson and upper James Bay coasts, and at least of irregular occurrence in spring in southern Ontario (Sutherland 2000).

  7. Ontario’s conservation responsibility

    ✔ Not in any category. Ontario makes up <10% of the species global range (COSEWIC 2009).

Secondary criteria (threats and vulnerability)

  1. Population sustainability

    ✔ Endangered. The species is unlikely to sustain itself in Ontario, since it is extinct or nearly so. The prognosis for the species is not good as the species clearly hasn't recovered from the catastrophic population declines experienced during the 1870s and 1880s, despite the protection afforded it by the Migratory Bird Convention Act and other legislated protection (Sutherland 2000). Current population estimates of between 0 and 50 surviving individuals (COSEWIC 2009) are only speculative. Evidence of breeding has not been obtained for over 100-years despite considerable search efforts of the known historic breeding range.

  2. Lack of regulatory protection for exploited wild populations

    ✔ Not in any category. Eskimo Curlew is currently listed in regulation under the province’s Endangered Species Act 2007, and Canada’s Migratory Birds Convention Act and Species At Risk Act.

  3. Human threats

    ✔ Insufficient information. Several 'modern' reports of Eskimo Curlew along the Hudson Bay coast have involved individuals purportedly shot by local residents (Gollop et al. 1986). However, because none of the specimens was preserved these reports have not been authenticated. It is therefore unknown to what extent transient Eskimo Curlews along Ontario’s Hudson Bay coast may be threatened by 'incidental take' (Sutherland 2000).

  4. Specialized life history or habitat-use characteristics

    ✔ Not in any category. Apparently peculiar among shorebirds was a strong predilection by the Eskimo Curlew for the fruits of Crowberry (Empetrum nigrum), on which it was in part dependent for food during fall migration. However, the species also fed on a wide variety of invertebrates and Crowberry was only a temporally important component of its diet during migration (Sutherland 2000).

COSSARO criteria met (primary/secondary)

  • Endangered – 6/1
  • Threatened – 0/0
  • Special concern – 0/0

Criteria for extirpated status

COSSARO's (1998) criteria indicate that a species will be a candidate for Extirpated status "in cases where there have been no confirmed reports or sightings in the past 40 years or 3 generations, whichever is less, despite repeated searches by knowledgeable observers at historical occurrence sites or at other sites where the species might be expected to occur". The last documented provincial sighting was in 1976, 34 years ago. The coastal areas of Hudson and James Bays are poorly surveyed in fall by birders, so it is possible that if occasional individuals still migrate through Ontario they could do so undetected. Generation time in the species is unknown, but related species are long- lived (10-30+ years) and age at first breeding is likely delayed, possibly to three years of age, as in the related Whimbrel (COSEWIC 2009). The species is close to meeting COSSARO's criteria for Extirpated status.

Summary

The Eskimo Curlew is one of the world’s most endangered birds and may already be extinct. There have been no fully substantiated records of the species anywhere since 1963, though there are still occasional sightings reported, including one from Ontario as recently as 1976. The species never bred in Ontario but was formerly a regular and common transient in fall along the Hudson and upper James Bay coasts. The species was evaluated by COSSARO as Extirpated in Ontario.

Information sources

AOU. 1983. American Ornithologists' Union Check-list of North American Birds (6th Ed.). American Ornithologists' Union, Allen Press, Lawrence, KS. Xxix + 877 pp.

Baldwin, D.H. 1967. The Fort Albany bird bones. Archaeological Newsletter, Royal Ontario Museum New Series 26:1-4.

COSEWIC. 2009. Update COSEWIC Status Report on Eskimo Curlew Numenius borealis. Committee on the Status of Endangered Wildlife in Canada, Ottawa. Two-month Interim Report (Sept. 2009). 31 pp.

COSSARO. 1998. Categories and Criteria for Status Assessment Committee on the Status of Species At Risk in Ontario. Unpublished document, February 1998. 9 pp. (downloaded from COSSARO Extranet site, May 2010)

Gollop, J.B. and C.E.P. Shier. 1978. Status Report on Eskimo Curlew, Numenius borealis, in Canada, 1978. COSEWIC Status Report prepared for Canadian Wildlife Service, Ottawa. 54 pp.

Gollop, J.B., T.W. Barry and E.H. Iverson. 1986. Eskimo Curlew: A Vanishing Species? Special Publication No. 17, Saskatchewan Natural History Society, Regina, SK. 160 pp.

NatureServe. 2010. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://www.natureserve.org/explorer (Accessed: May 28, 2010).

Sutherland, D.A. 2000. COSSARO Candidate V, T, E Species Evaluation Form for Eskimo Curlew (Numenius borealis). Committee on the Status of Species At Risk in Ontario. February 2000. 10 pp.

Wild Species, 2005. General Status Search Tool. [http://www.wildspecies.ca/]. (Accessed May 28, 2010).

Appendix 1

Northeastern North America rank, status and decline

Province/state Rank
CT SHN (NatureServe 2010)
DE Not present (NatureServe 2010)
IL SXN (NatureServe 2010)
IN SXN (NatureServe 2010)
IA SXN (NatureServe 2010)
KY Not present (NatureServe 2010)
MA SX (NatureServe 2010)
MB Not present (NatureServe 2010). However a MB record is mentioned in COSEWIC (2009) and MB has assigned a General Status rank (at risk), and MB is listed as a range jurisdiction by COSEWIC/SARA. Considered to be S1, S2, SH, or SX for the purposes of this evaluation.
MD SXN (NatureServe 2010)
ME SXN (NatureServe 2010)
MI Not present (NatureServe 2010)
MN SXM (NatureServe 2010)
NB SXM (NatureServe 2010)
NH Not present (NatureServe 2010)
NJ SXN (NatureServe 2010)
NS SXM (NatureServe 2010)
NY SXN (NatureServe 2010)
OH SNA (NatureServe 2010); presumably considered accidental in OH
ON SHN (NatureServe 2010)
PA Not present (NatureServe 2010)
PE SHN (NatureServe 2010)
QC SX (NatureServe 2010)
RI SNA (NatureServe 2010); presumably considered accidental in RI
VA Not present (NatureServe 2010)
VT Not present (NatureServe 2010)
WI Not present (NatureServe 2010)
WV Not present (NatureServe 2010)

Occurs as a native non-accidental species in 16 of 27 northeastern jurisdictions SRANK or equivalent information available for 16 of 16 jurisdictions (100%) S1, S2, SH, or SX in 16 of 16 jurisdictions (100%)

Part 2 Ontario evaluation using COSEWIC criteria

Regional (Ontario) COSEWIC criteria assessment

Criterion A – declining population

No. Historical population decline is beyond the time frame to qualify for this criterion. Population trend over the last 3 generations is unknown. No Ontario records since 1976.

Criterion B – small distribution and decline or fluctuation

No. Species has only ever been a transient in Ontario.

Criterion C – small population size and decline

No. Population size in Ontario unknown; no records in more than 30 years.

Criterion D – very small or restricted

Endangered D1. Meets Endangered D1 with a total of <250 mature individuals.

Criterion E – quantitative analysis

No. No quantitative analysis available.

Rescue effect

No. Unlikely to be rescued from adjacent jurisdictions since the species is extinct or nearly so.

prepared by Michael J. Oldham, 28 May 2010.