Black bears along the urban-wildland interface in northwestern Nevada increasingly rely on human food sources when natural forage fails — and this study shows that a late spring frost is a particularly strong trigger for that failure, more so than winter snowpack. Using 25 years of capture-recapture data on 509 bears (1998-2022), we found that late final-freeze dates were associated with lower natural survival and a higher probability that a bear would be killed by a vehicle strike or removed by wildlife managers.
As climate change increases the frequency of these “false spring” events — warm early-season temperatures followed by a hard freeze that kills flowers and fruit before they can set mast — human-bear conflict in the region is likely to become more frequent and severe. Anticipating these events could help wildlife managers respond proactively rather than reactively.
Citation: Shoemaker, K.T., Reich, H.E., Williams, P.J., Osterhout, M.J., Vasquez, J.P., Beckmann, J.P., Lackey, C.W., Stewart, K.M. 2025. Late season frosts and changing snowpack may exacerbate human-bear conflicts. Ecosphere 16(8):e70379. https://doi.org/10.1002/ecs2.70379