STATUS OF 5 BIRD SPECIES ASSESSED BY COSEWIC IN MAY
"Twice a year, the independent Committee on the Status of Endangered Wildlife in Canada (COSEWIC) makes recommendations that the federal government uses to consider species’ legal protections under the Species at Risk Act. Birds Canada volunteers are at the foundation of this process.
'Citizen Science observers across the continent are fundamentally important in determining population trends for many species', commented Richard Elliot, 'we couldn’t do this without you.'
There are 7 COSEWIC status categories: Extinct, Extirpated (no longer exists in the wild in Canada, but still exists elsewhere), Endangered, Threatened, Special Concern, Data Deficient (meaning not enough information is available to assess the species), & Not at Risk. In May 2021, 26 species or discrete populations of wildlife were assessed, including 5 birds. This batch includes the usual indications of grave concern, but also room for a little cautious optimism.
The dainty, diminutive Ross’s Gull, with its soft pink, grey, & powder-white adult plumage, is among the most beautiful of seabirds. It is a rare treat to see one, & unfortunately, the likelihood of that happening in Canada is lessening. COSEWIC assessed Ross’s Gull as Endangered, 2 categories higher than 25 years ago. Fewer than 20 individuals are now known to breed in Canada, & no chicks have fledged in 14 years from Canada’s only known colony in the High Arctic. Canadian Low Arctic nest sites have been abandoned since the species was last assessed (as Threatened) in 2007. Major threats include chick mortality caused by Arctic Terns, & contamination from airborne toxic chemicals... Almost all of the global population of Ross’s Gull breeds in northeast Siberia, & at the global level, the species is assessed by BirdLife International as Least Concern: a silver lining, &, it is possible that small numbers may occur undetected in the Canadian High Arctic.
Short-eared Owl is one of the world’s most widespread owls. Active day & night, this nomadic, ground-nesting species breeds in open habitats in all Canadian provinces & territories... New population estimates derived from Breeding Bird Atlas data suggest that the Canadian population is approximately 31,000 mature individuals, which is only about 10% of previous estimates. A decline of more than 30% over the past 3 generations is inferred from data from the Breeding Bird Survey & Christmas Bird Counts. It is consequently designated Threatened; previous assessments in 1994 & 2008 categorized it as Special Concern. Continuing declines are projected due to ongoing loss of nesting & wintering habitat from crop conversion, agricultural intensification, urbanization, & invasive plants, &, in low Arctic habitats, climate-driven increases in shrub growth will further reduce prey availability & increase predation risk.
The fruit-eating, woodland–dwelling Band-tailed Pigeon of southwestern British Columbia still qualifies as Special Concern, as it did in 2008. However, Canadian birds are losing breeding habitat to forest harvest & urbanization, with the Breeding Bird Survey showing a continuing long-term decline of 11% in 3 generations. Species-specific surveys at sites where these birds congregate to consume mineral-rich water or soil suggest localized declines of about 40% in 3 generations. Most Canadian birds winter in the western United States where they are exposed to habitat loss, hunting, & a prevalent, parasite-caused disease. So the Band-tailed Pigeon may soon qualify for Threatened unless these threats can be mitigated.
Encouraging news concerns a public favourite, & one of the world’s most widespread birds, the Barn Swallow. Readers will be pleased to learn that the substantial decline over 2 decades (starting in the late 1980s) prompting its designation as Threatened in 2008 has stabilized over the past 10 years. Ongoing declines in some provinces are offset by a substantial increase in Saskatchewan, warranting its re-designation as Special Concern. Although the Canadian population remains large, estimated at 6.4 million mature birds, it may once again become Threatened if threats continue or worsen.
The striking Ferruginous Hawk is the only bird of prey confined to the grasslands of the North American Great Plains. Population trends in the Canadian range of southern Alberta, Saskatchewan, & far southwest Manitoba have been stable or even slightly increasing over the past 3 generations, prompting a reclassification from Threatened to Special Concern. This hawk’s history of classification has seen it bounce between Threatened & Special Concern since initial designation as Threatened in 1980. This latest designation recognizes that the species may become Threatened again in the absence of effective management of ongoing loss of foraging & nesting habitats from threats such as displacement by energy production, increased competition, disturbance at nest sites, & persecution of prey."
By Pete Davidson, Senior Conservation Advisor, Birds Canada & COSEWIC Birds Specialist Sub-Committee Member; & Dr. Richard D. Elliot & Dr. Marcel H. Gahbauer, Co-Chairs of COSEWIC Birds Specialist Sub-Committee
June 25/2021
birdscanada.org
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