Linner-Warren, K., B.D. Bibles, and C.W. Boal. 2023. Seasonal abundance and habitat associations of American kestrels on the Southern High Plains of Texas. Journal of Raptor Research 57:251-263.
ABSTRACT.—The American Kestrel (Falco sparverius) is in general decline across its North American distribution but the population in the Southern High Plains region currently appears to be stable. Historical evidence suggests the region had a very low presence of kestrels, and that their current abundance is due to landscape changes associated with European settlement. We conducted monthly surveys for American Kestrels across two years to estimate seasonal densities and identify land cover associations in the Southern High Plains of Texas. We found an overall estimated density of a 0.99/km2 (95% CI = 0.406, 1.582). across the two-year period with seasonal estimated densities highest in autumn and winter (0.92 – 2.53/km2), and lowest in spring (0.49 – 0.67/km2). Whereas other studies have found temperature influenced detection of wintering kestrels, we found an interaction of drought conditions and snow most strongly influenced detection rates in our study area. Kestrels largely used land cover types in proportion to availability but there was some evidence of seasonal shifts. In generally, they appeared to select against cotton fields and select for areas with woodlots, abandoned or occupied houses, and barns, all of which likely provided nesting and roosting opportunities. Our study provides the first contemporary assessment of seasonal abundance and habitat associations of American Kestrels in the Southern High Plains where their presence and abundance is has been unintentionally facilitated by landscape changes following settlement. We provide a baseline for population monitoring and studies assessing response to additional landscape changes (e.g., wind energy) and a changing climate.