Large mammals are finding clever ways to beat the heat

Every summer, things heat up in the Greater Yellowstone Ecosystem – a massive, wild region that stretches across parts of Wyoming, Montana, and Idaho.

For animals that live there, especially big mammals like moose, elk, and bison, staying cool isn’t just about comfort. It’s about survival.

In a new study from Montana State University, researchers looked at how these large mammals respond to rising summer heat.

The team wanted to know: do animals change how they move and behave when it gets too hot? And what makes the biggest difference in how they respond – their own physical traits, or the environment around them?

What the researchers found came as a surprise. The landscape itself – whether it was full of variety or just flat and plain – had a greater effect on animal behavior than their size, sex, or other traits.

Some habitats are hotter than others

All the animals studied responded to the heat in similar ways. They slowed down. They looked for shade. But some groups had to work a lot harder to stay cool. That’s because their habitats didn’t give them many options.

Animals that lived in wide-open, flat areas – what scientists call “homogeneous environments” – had to change their behavior more dramatically than animals in more diverse habitats.

For example, pronghorn living in the prairie of Wyoming’s Shirley Basin had to travel farther to find shade, since their environment had fewer trees and less natural cover. That extra effort made a difference.

Tracking large mammals in the heat

The research team studied nine species, including bison, bighorn sheep, mountain goats, moose, mule deer, elk, pronghorn, wolves, and cougars.

The team analyzed GPS data from more than 15 years, covering the hottest part of each year – from mid-June through August.

The data came from several organizations, including the National Park Service, the U.S. Geological Survey, the Bureau of Land Management, and state wildlife agencies.

Physical traits and heat tolerance

The team also looked at the animals’ biological traits – like size, physiology, and sex.

The goal was to investigate whether these traits make a difference in how large mammals handle the heat. But there was no clear link.

The results suggest that the physical features of an animal don’t predict how well it can handle hotter temperatures. Instead, the habitat itself – and how much variety it offers – plays the biggest role.

“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 Justine Becker, co-lead author of the study.

Animal behavior as a buffer

Behavioral flexibility – or “plasticity” – is what helps animals deal with sudden changes in temperature.

Because behavior can change quickly, plasticity gives animals a way to respond to climate change faster than evolution would allow.

“We often think of climate change as a huge ecological challenge for most species, and it absolutely is, 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,” said Becker.

“They don’t need to wait around for the process of evolution to take its course.”

New insights for wildlife management

The study’s findings could change how wildlife habitats are managed. A large part of what management agencies work on is habitat treatment, modification, and protection, Becker noted.

“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.”

“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.”

Jerod Merkle, a wildlife ecologist at University of Wyoming, added that landscapes need to be permeable, such that the animals can access all these different habitats when the heat waves come.

In other words, it’s not enough to protect animals where they are. They need access to a mix of landscapes – shady forests, open meadows, hills, and valleys – so they can find what they need when temperatures spike.

Saving large mammals from rising heat

This kind of research takes teamwork. The data used in the study came from years of tracking animals across multiple states and ecosystems.

Many different organizations – state and federal – shared information so the researchers could get a clear picture of what was happening across the entire region.

“Such syntheses, collaboration and comparative analysis are invaluable to the production of new ecological knowledge,” said Becker.

The takeaway? Big animals aren’t helpless against climate change. They’re smart, adaptable, and quick to respond when their surroundings allow it. But they need the right kinds of environments to make those choices.

And when the heat hits harder each year, having the right place to go might be what saves them.

The full study was published in the journal Ecosphere.

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