American kestrel population trends and vital rates at the continental scale

Ecosphere
By: , and 

Metrics

1
Crossref references
Web analytics dashboard Metrics definitions

Links

Abstract

The American kestrel (Falco sparverius, hereafter referred to as kestrel) has declined across much of its North American range since at least the mid-1960s. Kestrel population dynamics have been explored through a multitude of local studies and two broad reviews of available data. Across large geographic extents, however, the demographic cause(s) of kestrel population declines remain(s) largely unknown. As part of a collaborative effort to elucidate the drivers of kestrel population declines, we developed a continental-scale integrated population model using band-recovery data, productivity data, and Breeding Bird Survey indices from 1986 to 2019 to estimate indices of annual population sizes, survival, and productivity rates across the continental United States. We detected a decline in population size of ~1%–2% per year. Overall estimates of population growth from 1986 to 2019 suggest a 29% decline in population size (95% CI = −34% to −23%). There was little evidence of a trend in brood size. However, survival of juvenile birds (mean = −0.015, SD = 0.008 and mean = −0.024, SD = 0.010 for females and males, respectively) and adult males (mean = −0.016, SD = 0.010) in the summer declined, suggesting that these vital rates could be contributing to declines in populations over time. Winter adult survival rates (mean = −0.004, SD = 0.009 and mean = −0.009, SD = 0.010 for females and males, respectively) also declined but to a lesser extent than summer survival. For juvenile birds, winter survival increased (mean = 0.006, SD = 0.008 and mean = 0.002, SD = 0.009 for females and males, respectively); however, this was not enough to offset declines in summer survival and annual survival rates declined over the time series. Annual adult survival was also low relative to previous research on kestrel survival rates. Given the importance of survival to population trends, our findings provide support for several previously proposed broad classes of factors potentially contributing to observed population declines: declines in arthropod prey, second-generation rodenticides, neonicotinoid insecticides, and predation.

Suggested Citation

Howell, P.E., Lawson, A.J., Davis Kristin P., Zimmerman, G.S., Robinson, O.J., Boggie, M.A., Eaton, M.J., Abadi, F., Brown, J.L., Heath, J.A., Smallwood, J.A., Steenhof, K., Swem, T., Rolek, B.W., McClure, C.J., Therrien, J., Miller, K.E., Milsap, B.A., 2026, American kestrel population trends and vital rates at the continental scale: Ecosphere, v. 17, no. 2, e70526, 18 p., https://doi.org/10.1002/ecs2.70526.

Publication type Article
Publication Subtype Journal Article
Title American kestrel population trends and vital rates at the continental scale
Series title Ecosphere
DOI 10.1002/ecs2.70526
Volume 17
Issue 2
Publication Date February 09, 2026
Year Published 2026
Language English
Publisher Ecological Society of America
Contributing office(s) Coop Res Unit Seattle, Southeast Climate Adaptation Science Center
Description e70526, 18 p.
Additional publication details