The Brown-headed Cowbird is an abundant bird of open prairie and agricultural land, with a breeding range that reaches from the west to the east coast of Canada. Results from the Breeding Bird Survey show that populations have decreased significantly at the national level since about 1970. However, in the Prairie Potholes Bird Conservation Region, the core of the species' range in Canada, the population has shown little overall change. As Canada's only true brood parasite, the species has been suspected of harming host species' populations, and has therefore been subjected to control programs, primarily in the United States (Lowther 1993). This species has been identified as a priority for conservation and/or stewardship in one or more Bird Conservation Region Strategies in Canada.
European settlement of North America, with the subsequent opening up of forested areas for agriculture, greatly benefited the Brown-headed Cowbird and facilitated its range expansion eastward (Lowther 1993). In its historical range in the Prairies, the population has remained stable, but elsewhere, populations have decreased substantially. Conservation concern is currently greater for the sensitive host species that it parasitizes in the United States, such as Kirtland's Warbler, Black-capped Vireo, and Least Bell's Vireo. Cowbird control programs have been used in the United States to protect Kirtland's Warbler (Lowther 1993).
Environment and Climate Change Canada and partners have developed Bird Conservation Region Strategies in each of Canada’s Bird Conservation Regions (BCRs). In these strategies, selected species are identified as priorities for one or more of the following reasons:
Select any of the sub-regions below to view the BCR strategy for additional details.