A recent study led by researchers from Montana State University and the University of Wyoming has found that large mammals in the Greater Yellowstone Ecosystem adjust their behavior in response to summer heat based more on their environment’s structure than on their own biological traits or the level of temperature increase. The findings were published in the journal Ecosphere.
Justine Becker, assistant professor in the Department of Ecology at Montana State University, co-led the research. The study included collaboration with several agencies, including the Bureau of Land Management, National Park Service, U.S. Geological Service, Wyoming Game and Fish Department, and Idaho Department of Fish and Game.
The research focused on nine large mammal species—bison, bighorn sheep, moose, mountain goats, mule deer, pronghorn, elk, wolves, and cougars—using GPS data collected from 2001 to 2019 across different populations within the Greater Yellowstone Ecosystem. Analysis centered on data from mid-June to late August when temperatures are highest.
The team aimed to understand how both environmental conditions and innate animal traits influenced behavioral responses to rising temperatures. They looked for patterns both across species and within specific populations.
“As far as we know, this is the first study of this nature that’s taken data from a lot of different populations of large mammals and looked at their behavioral plasticity at the same time,” said Becker. “We were really interested in seeing whether there was any kind of generality in their responses to increasing temperatures, as well as species-specific responses that might be different from one another.”
The study found that all observed populations sought cooler conditions and reduced movement during hot periods. However, animals living in homogeneous environments—those with less varied landscapes—made more dramatic behavioral changes than those living in diverse habitats. For example, pronghorns in Wyoming’s Shirley Basin altered their movements significantly to find shade due to limited tree cover.
Researchers also considered factors such as sex, physiology, and body size but did not find links between these traits and how animals changed behavior during heat waves. The authors suggest more research is needed on individual characteristics like coat color.
Becker noted that these results are promising because they show large mammals can quickly adapt their behavior to manage heat stress—a key ability since physical adaptation through evolution occurs slowly for larger animals.
“We often think of climate change as a huge ecological challenge for most species, and it absolutely is,” Becker said. “But at the same time, behavior is this really amazing way that animals are able to buffer themselves against these changes because they can do it right away. They don’t need to wait around for the process of evolution to take its course.”
The findings may have implications for wildlife management strategies by highlighting the importance of considering entire ecosystems rather than focusing solely on individual species.
“A large part of what management agencies work on is habitat treatment, modification and protection. We’re hopeful that this study gives a general sense of the kinds of environmental features needed to help these animals and what types of habitats are going to be important for them in the future,” Becker said.
Jerod Merkle from the University of Wyoming added: “We saw a large variety of responses during hot days across individuals and across species. This result tells us that animals have options, and maintaining a landscape that is a mosaic of these different habitats is key. Further, landscapes need to be permeable, such that the animals can access all these different habitats when the heat waves come.”
Becker emphasized collaboration was essential: “Such syntheses, collaboration and comparative analysis are invaluable to the production of new ecological knowledge,” she said.
