Dietary shift in the American Kestrel under severe drought conditions in the southern Baja California Peninsula

Abstract

Generalist predators often adjust their diets when environments are stressed by extreme climatic conditions. The American Kestrel (Falco sparverius) is a generalist raptor, and most studies have identified rodents and insects as its primary prey throughout its distribution. We examined prey capture rates of American Kestrels during the non-breeding and breeding seasons (2024–2025) in the southern Baja California Peninsula in a period of extreme drought. Overall prey capture rates did not differ significantly between the non-breeding (0.78 ± 0.23 prey·h⁻¹) and breeding seasons (1.13 ± 0.24 prey·h⁻¹). However, we detected significant seasonal differences in prey composition (ANOSIM, P = 0.005, R = 0.31). During the non-breeding season, diets consisted largely of insects, with vertebrates—primarily birds—being scarce. In.

contrast, during the breeding season kestrels shifted markedly toward reptile prey. The limited consumption of rodents by kestrels was remarkable, particularly during the non-breeding season, and may have consequences for kestrels once the breeding season begins. Evidently, drought had important consequences for the diversity of prey consumed and subsequently impacted the breeding performance of kestrels in the area.