Snowy Range Moose Project

Moose have evolved to thrive in cold-weather environments of northern latitudes, but as moose distribution has expanded south in the last century, the warmer temperatures of these regions may be challenging their ability to manage heat stress. For this cold-adapted species that lacks the ability to sweat and experiences heat stress at surprisingly low temperatures, the energy it takes to stay at a safe temperature can affect other parts of life, like getting enough food for reproduction and survival. Moose of the Snowy Range in southern Wyoming occupy some of the southern-most ranges of the species, providing an opportunity to explore how moose cope with environmental conditions at the extreme of their range.

This project sought to understand how moose use their environment to deal with temperature, and it concluded in 2021.

A large female moose stands in the open sagebrush, looking directly at the camera. Her coat is thick and healthy, and the sky behind her is a clear blue.
Photo credit: Alex May

Main findings

A yellow weather monitoring device sits in a moose's bed site, with grass trampled down and bare ground showing. The surroundings are lush and green with vegetation.
Photo credit: Tana Verzuh

Moose rely on bed sites to keep cool.

Moose of the Snowy Range are at the southern extent of the species’ distribution, and may be more vulnerable to heat stress when compared with those of more northerly populations because of limitations in habitats that provided needed thermal refuge.

We found that moose selected for bed sites with cooler temperatures with moist or wet ground or with standing water. Moose avoided bedding down in dry, open, and sparsely vegetated areas like dry meadows, fire-affected areas, and sagebrush. Overwhelmingly, wet ground was most effective at reducing heat stress, even when compared with canopy cover. On a summer day, moose could overheat at temperatures as low as 54°F (!!) when bedded on dry ground with no shade. In contrast, with wet ground and 100% shade, moose were not at risk of overheating until temperatures exceeded 82°F.

This research suggests that moose need habitat with wet ground or standing water to stay cool, which can help to guide habitat and management efforts for moose.

This research was published in the paper, “Behavioral flexibility in a heat-sensitive endotherm: the role of bed sites as thermal refuges” by Tana L. Verzuh, L. Embere Hall, Teal Cufaude, Lee Knox, Corey Class, and Kevin L. Monteith in Animal Behavior in 2021.

A female moose peers through sparse branches.
Photo credit: Tayler LaSharr

Moose select for habitat that can help keep them cool.

Moose like to hang out in the willows, and although willows offer abundant sources of food for moose, there might be another reason they spend so much of their time in willows: to stay cool.

Moose overwhelmingly selected bed sites and home ranges with lower risk of overheating and also had higher amounts of willows. In line with other research, bed sites with moist and wet ground conferred the lowest risk of overheating. Moose also were more likely to select home ranges closer to roads if those ranges had higher willow percentages and low overheating risk.

This research provides further evidence of the importance of riparian areas to moose, which can help to shape habitat management priorities.

This research was published in the paper, “Behavioral responses of a large, heat-sensitive mammal to climatic variation at multiple spatial scales” by Tana L. Verzuh, Savannah A. Rogers, Paul D. Mathewson, Alex May, Warren P. Porter, Corey Class, Lee Knox, Teal Cufaude, L. Embere Hall, Ryan A. Long, and Kevin L. Monteith in Journal of Animal Ecology in 2022.

Project leads

Tana Verzuh

Tana stands on the rocky banks of a river, holding a very small frog.

Alex May

Alex May stirs a skillet full of food on a camp stove with tents and red rocks in the background.

Collaborators, partners, and funders

This work was supported by the Wyoming Game and Fish Department and the Wyoming Governor’s Big Game License Coalition. Lee Knox, Embere Hall, Teal Cufaude, and Corey Class provided valuable assistance and collaboration.