Bears resort to rummaging through our food supplies when late-spring frosts destroy their natural food sources
by Claudene Wharton, University of Nevada, Reno
October 14, 2025
We get frustrated when those late-spring frosts decimate our tomato plants that we so enthusiastically planted after we thought spring had finally arrived. But, imagine if that was our only food source. Researchers at the University of Nevada, Reno are documenting how, in some years, spring temperature swings are wiping out natural food sources for black bears in western Nevada’s Sierra Nevada mountain range, and forcing them to seek their sustenance from our yards and gardens, and sometimes even our pantries and chicken coops.
“We all notice when there’s a late frost, from the effects on our yards and gardens,” said Kelley Stewart, leader of the research project and professor in the University’s Department of Natural Resources & Environmental Science, housed in the College of Agriculture, Biotechnology & Natural Resources. “It’s much worse up on the hills for bears and other wildlife. The temperatures are more severe. The plants start growing and flowering with an early spring warm-up, and then there’s a late-season frost that takes them all out. It especially affects berries and the harder things like acorns, pinenuts and other things that nature normally provides for the bears.”
That drives the bears to seek food from human sources, increasing human-bear interactions. Stewart points to 2022, a year with a late frost date. That year, the number of bear complaints in the study area ballooned from about 500 reported in an average year to about 1,500, according to Heather Reich, who also worked on the project. Reich, an alum of the department’s graduate program, is co-lead author of the article publishing the project’s results featured in the journal Ecosphere early this fall. She now operates her own business, Bear-ier Solutions, to help provide deterrents for bears and prevent the need for lethally removing them.
Keep reading: https://www.unr.edu/nevada-today/news/2025/bear-climate-research
Read the Ecosphere paper: https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.70379