Novel Predatory and Carnivorous Behaviors of California Ground Squirrels Independent of the Age and Sex of Hunters

Abstract

Dietary flexibility allows animals to respond adaptively to food pulses in the environment. Here we document the novel emergence of widespread hunting of California voles and carnivorous feeding behavior by California ground squirrels. Specifically, we aimed to investigate whether the age and sex of squirrels explained the extent to which they engaged in hunting, consumption, and/or competition over voles. This work is part of a long-term study at Briones Regional Park in California where squirrels of known ages and sexes are regularly live-trapped, marked, and released. In 2024, from June 10th to July 30th, we recorded all sightings of squirrels hunting, killing and/or consuming voles both opportunistically on trapping days and during formal behavioral observations. We found no significant difference in the age-sex composition of those individuals that engaged in any of these behaviors compared to those that did not hunt, consume, or compete over voles. Thus, juvenile and adult ground squirrels of both sexes depredate, consume, and/or compete over vole prey. Given that participation in hunting and consumption of voles was so widespread across members of the study population, future studies are required to understand whether these novel foraging behaviors were learned individually or spread socially throughout the study population.