Frogs and other amphibians have thrived on the planet for over 350 million years, adjusting to dramatic changes to their world over the millennia. As animals that are reliant on external sources of heat to regulate their body temperatures, frogs are highly sensitive to temperature and moisture patterns in their surrounding environment – both of which are rapidly changing in a warming climate. Scientists are concerned that rapidly changing winter weather conditions could make it difficult for some frogs to survive the winter. 

In a new article in Diversity and Distributions, National CASC researchers Sarah Weiskopf and Laura Thompson and co-authors determined how severe winter weather, measured by temperature and snow cover, affects survival of overwintering frogs in the eastern United States and compared the sensitivity of species with different breeding times and overwintering strategies. Using data from the North American Amphibian Monitoring Program (NAAMP), a citizen-science volunteer project that collected data on the presence or absence of frogs in areas of the eastern U.S. over 15 years, the researchers discovered that most species had increased presence in years with warmer than average temperatures and heavier snowfall. This evidence suggests that less snowfall in the coming years—which is projected under climate change—could reduce species’ survival, while milder winters could improve their chances. The researchers also found that most frogs were sensitive to winter severity, regardless of breeding time or overwintering strategy. 

This work highlights the vulnerability of this group of amphibians to rapid climate change and demonstrates that global changes have nuanced impacts on species survival. Continued monitoring of this group is needed to better understand how these conflicting conditions will impact individual species survival. 

This work benefitted from data gathered by the North American Amphibian Monitoring Program (NAAMP) and the U.S. Geological Survey Amphibian Research and Monitoring Initiative (ARMI).