Canadian Breeding Birds at Greater Risk
Two bird species that breed in Canada have been uplisted to a higher risk category of becoming extinct. The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) met in November and classified the Chestnut-collared Longspur as Threatened and upgraded the Bicknell's Thrush from Special Concern to Threatened. A "Threatened" status indicates a species that is likely to become "Endangered" if nothing is done to reverse the factors leading to its decline.
Both of these birds are habitat specialists that require specific and increasingly rare conditions to survive. Habitat loss and fragmentation are at the heart of their population declines.
The Chestnut-collared Longspur (Calcarius ornatus) is a medium-sized, sparrow-like bird that occurs in Alberta, Saskatchewan and Manitoba. It prefers to breed in short-grass or mixed-grass prairie sites recently grazed or disturbed by fire, but its breeding habitat is being fragmented by road development associated with the energy sector. This grasslands species was assessed as Threatened because it has suffered severe population declines since the late 1960s and the results of several surveys suggest that the declines have continued over the last decades, albeit at a slower rate. Grasslands are the most threatened biome in North America.
Bicknell's Thrush (Catharus bicknelli) has one of the most restricted breeding ranges among the forest birds of North America. This medium-sized thrush was originally assessed in April 1999 as a species of Special Concern and is now considered Threatened. It breeds in montane forests in Quebec, New Brunswick, Nova Scotia and the northeastern United States, and it spends the non-breeding period in very restricted highland forests in Haiti and the Dominican Republic.
Preliminary results from the Maritimes Breeding Bird Atlas project suggest a 40% decline in the area occupied over the last three generations, while the High Elevation Landbirds Program suggests more dramatic declines in the same regions. Recent surveys in Quebec also indicate declines in some locations. The species faces range-wide habitat pressures, as it is vulnerable to ongoing and future planned management practices such as pre-commercial thinning in regenerating forests that reduces cover for nests and increases nest predation. Acid rain, climate change and the spruce budworm have also reduced the suitable high-elevation habitat for these birds in North America, while forest habitat is now restricted almost exclusively to a handful of Important Bird Areas in the Greater Antilles.
Nature Canada supports these listing recommendations for inclusion on Canada's official Species At Risk list and is also working towards the conservation of these two species.
In the case of the Chestnut-collared Longspur, we are working to permanently protect Suffield National Wildlife Area from further gas development that will affect the habitat of this and many other grassland species at risk. In the case of Bicknell's Thrush, we are supporting our partner Haiti Audubon Society to improve community livelihoods and conservation practices in Haiti's Macaya National Park, where this species is known to winter.
These two species are examples of the need for conservation efforts along birds' entire migratory route or flyway.
Sources: COSEWIC Wildlife Species Assessments (detailed version), November 2009; All About Birds Guide – Bicknell's Thrush; All About Birds Guide – Chestnut-collared Longspur; Species At Risk Public Registry – Bicknell's Thrush