UWEC CERCA 2026

Widespread human impacts – from climate change to unprecedented rates of human visits to once relatively untouched wilderness areas – contribute to rapidly changing selective pressures on wildlife. Long-term studies on marked individuals can offer insights into population and community dynamics over time. The current research aims to reveal the demographic and behavioral patterns of California ground squirrels (Otospermophilus beecheyi) before and after a boom year of California voles (Microtus californicus). As part of a long-term field study in California, we have live-trapped, marked, and observed individual ground squirrels since 2013. In Summer 2024, we documented the emergence of widespread hunting and consumption of voles by ground squirrels in our two study populations. Here we document the subsequent crash in squirrel abundance and surge in predator sightings in Summer 2025. We report on these demographic, behavioral, and physiological consequences of the vole boom year using an integrated approach. Our findings offer insights into how periods of prosperity (e.g., boom years) and catastrophic turnover events (e.g., demographic crashes) shape wildlife populations that generate ripple effects within ecological communities.