JACKSON, Wyo. — This month might be one of the last opportunities to spot a Uinta ground squirrel in the Greater Yellowstone Ecosystem (GYE) before their hibernation, which begins as early as mid-July and lasts up to eight months.
While often overlooked in favor of the local charismatic megafauna, Uinta ground squirrels are a unique and integral part of the GYE. According to Yellowstone National Park (YNP), these squirrels live in disturbed or heavily grazed grasslands, sagebrush and mountain meadows up to 11,000 feet. They can be identified by a grayish back with fine white spots, a tan to cinnamon-colored nose and shoulders and a tail that is grayish underneath.
Uinta ground squirrels provide essential food for long-tailed weasels, hawks, coyotes, badgers and grizzly bears; Jackson Hole News & Guide previously reported they’re considered “salmon of the interior West.”
“Anything that eats meat eats ground squirrels,” Kevin Taylor, lead guide with Wildlife Expeditions of Teton Science Schools, tells Buckrail. He notes they’re a staple food particularly for badgers.
Uinta ground squirrels are also a source of protein for each other. YNP confirms Uinta ground squirrels consume road-killed members of their own species in addition to their diet of grasses, forms, mushrooms, insects and other carrion, something Taylor says he’s observed.
“I’ve never seen a ground squirrel scavenge on a dead raccoon, but I’ve definitely seen them scavenge on their own species,” Taylor tells Buckrail.
Taylor, from his ecologist viewpoint, draws a parallel between this cannibalism and eating the placenta after birth to not waste the critical protein source. Taylor suggests that a familiar, same-species carcass might be viewed the same way by Uinta ground squirrels.
Currently, Uinta ground squirrels are heading into hyperphagia, a period of excessive eating to increase fat stores right before hibernation.
“When you see a male ground squirrel just before going into hibernation, it looks like a bear,” Taylor says. “You can see the fat rolling across their body as they’re moving.”
According to Taylor’s observations, big males tend to go into hibernation first, while females follow in early August. He hypothesizes that the females need a little bit more time to build up fat stores after their additional energy expenditure in the early summer producing milk for their young. Juvenile ground squirrels, born in May, will be the last to hibernate in the second half of August, also needing more time to build fat stores; however, Taylor stresses that many juveniles won’t actually acquire enough fat to make it through the winter.
Uinta ground squirrel hibernation is considered a “true” hibernation, where they lower their metabolism, heart rate, respiratory rate and body temperature. But Taylor says he often gets asked why this species goes into hibernation so early, when there’s still an abundance of green vegetation to be foraged.
His answer is that there’s likely an evolutionary cost-benefit analysis happening; being awake as a ground squirrel takes a significant amount of energy due to the constant vigilance required of these prey. At a certain point after the optimal summer time for vegetation’s biomass and digestibility, reducing energy output outweighs the benefits of eating more vegetation.
Uinta ground squirrels will be gone until the spring, reemerging based on snowmelt. Areas like Kelly Warm Springs, where the snow melts faster, will see Uinta ground squirrels first.
