Raptor Population Index

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Species Assessment:
Swainson's Hawk (Buteo swainsoni)

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The 10-year migration count trends for the Swainson’s Hawk suggest stable populations across North America with 93% of 14 total sites showing stable counts during this span. Increasing observations were seen at one site. Regionally, populations are mostly stable with one increasing report in the West Region (see pie charts and trend maps below). 20-year count trends (not shown) also reflect a stable population with some increases in the West Region (Gulf Region: 5 stable; West Region: 3 stable, 1 increase). Average annual numbers are highest at sites in Veracruz, Mexico, with 387,209 on average in Chichicaxtle and 244,327 per year at Cardel, Veracruz. In the United States, Corpus Christi, Texas, recorded the highest average count of 6,010 per fall. These sites reported stable counts for the past decade.

Winter survey data from the Christmas Bird Count (CBC) show stable 10-year trends continent-wide with significant declines observed in Washington. The Swainson’s Hawk has no federal status under the United States Endangered Species Act but is listed as a Species of Special Concern in Utah, Nevada, Oregon, and Washington, and as Threatened in California. Evidence suggests that the population has been reduced by as much as 90% from its pre-colonial numbers. Swainson’s Hawks commonly breed in areas of intense agriculture but require access to trees for nesting and roosting. They are especially vulnerable to habitat loss due to urbanization and land development and environmental contaminants such as agrochemical compounds.

Swainson's Hawk<br>Photo by Vic Berardi

Photo by Vic Berardi

Please cite this page as:
    D. Oleyar, D. Ethier, L. Goodrich, D. Brandes, R. Smith, J. Brown, and J. Sodergren. 2021. The Raptor Population Index: 2019 Analyses and Assessments.