A new study from the University of Nevada, Reno (UNR), finds that these frosts can wipe out key food sources like berries, acorns, and pine nuts. With their natural buffet gone, bears are wandering into mountain towns and neighborhoods in search of a meal.
Researchers analyzed data from more than 500 black bears captured between 1998 and 2022 in the Sierra Nevada. They found a clear pattern: years with late frosts led to spikes in human-bear conflicts. In one season alone, bear complaints in the study area reached about 1,500 — roughly three times higher than an average year.
“When the frost hits late, it kills the whole food crop up there,” said Kelley Stewart, a UNR wildlife ecologist and co-author of the study. “So what happens is a loss of natural foods. And then the bears start looking.”
Co-author Heather Reich said the research underscores the importance of continued bear tracking and education to help wildlife managers anticipate when conflicts are most likely.
“We're getting a lot of human-bear conflicts increasing everywhere, and this is just one more trigger of that conflict,” Reich said.
She added that during lean years, bears that cause minor trouble shouldn’t automatically be labeled “problem bears.” Instead, she said, they’re often just trying to survive when nature comes up short.
The researchers hope their findings will help communities prepare for tougher seasons and encourage people to show a little grace when hungry bears come looking for food.
This story was produced by the Mountain West News Bureau, a collaboration between KUNR, Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNC in Northern Colorado, KANW in New Mexico, Colorado Public Radio, KJZZ in Arizona and NPR, with additional support from affiliate newsrooms across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting and Eric and Wendy Schmidt.
