Thirty Years of Migration and Winter Count Data Indicate Regional Differences in Population Trajectories for American Kestrels in North America

Using fall migration trend data from the Raptor Population Index analyses (n = 59 count sites) paired with winter Christmas Bird Count trend data at the USA state and Canadian province level, we evaluated continental and regional patterns in trends of American Kestrels (Falco sparverius) over the last 30 yr. Long-term trends at the continental and regional level showed widespread declines in the number of kestrels counted during both fall migration and winter. The lone exception was in western North America where declining migration counts were evident, but could at least partly be explained by increasing winter counts. These results suggest that western kestrels are shifting migratory tendencies, migrating shorter distances (short-stopping), or are not migrating at all. This contrasts with patterns in central and eastern North America where kestrel counts declined in both fall and winter over the last 20- and 30-yr periods. Recent trends (2009–2019) showed less widespread declines in both fall and winter across North America and for most regions, suggesting kestrel declines might have moderated in the past decade. However, the species remains at significantly reduced abundance levels compared to the recent past and has not rebounded.

Title	Thirty Years of Migration and Winter Count Data Indicate Regional Differences in Population Trajectories for American Kestrels in North America
Creator	Smith, R.
	Ethier, D.
	Brown, J.
	Oleyar, D.
	Brandes, David
	Sodergren, J.
	Goodrich, L. J.
Publisher	Journal of Raptor Research
Academic Department	Civil & Environmental Engineering
Division	Engineering
Organization	Lafayette College
Date Issued	June 2023
Date Available	2023-07-17
Type	Article
Language	English
Keyword	winter trends
	Falco sparverius
	American Kestrel
	Raptor Population Index
	trend summary index
	Christmas Bird Count
	migration trends
	population trends
Bibliographic Citation	Oleyar, D., et al. (2023 June) "Thirty Years of Migration and Winter Count Data Indicate Regional Differences in Population Trajectories for American Kestrels in North America." Journal of Raptor Research 57 (2): 146–153.
Standard Identifier	DOI 10.3356/JRR-22-17
Standard Identifier	Handle 10385/m900nv94z
Permalink	http://hdl.handle.net/10385/m900nv94z
Rights Statement	In Copyright
Rights Holders	The Raptor Research Foundation, Inc.