Wyoming’s high country holds a quiet signal that spring has truly arrived — a round, furry shape perched atop a boulder, scanning the landscape after months underground. Marmots are among the state’s most dedicated hibernators, spending more of their lives asleep than almost any other mammal in the Rockies.
If you’re curious about when marmots come out of hibernation in Wyoming, what they do once they surface, and where you’re most likely to see one, this guide walks you through everything you need to know about these charismatic alpine residents.
Which Marmot Species Live in Wyoming
Wyoming is home to one primary marmot species that you’re very likely to encounter in the wild. The yellow-bellied marmot (Marmota flaviventris), also known as the rock chuck, is a large, stout-bodied ground squirrel in the marmot genus. It’s the marmot you’ll find sunning itself on boulders throughout the state’s mountain ranges.
The yellow-bellied marmot lives in southwestern Canada and the western United States, including the Rocky Mountains and the Sierra Nevada. Its range extends into the montane and basin regions of Wyoming, eastern Montana, Colorado, and southern Alberta.
The fur is mainly brown, with a dark bushy tail, yellow chest, and white patch between the eyes, and they weigh up to approximately 5 kilograms (11 pounds). That distinctive yellow belly is your easiest field identification clue.
Key Insight: A small but notable population of melanistic (dark-furred) yellow-bellied marmots exists in the Teton Range. There is a small population of black marmots — melanistic marmots — in the Tetons of Wyoming. If you spot what looks like an unusually dark marmot near Jackson, that’s why.
The yellow-bellied marmot is one of fourteen species of marmots and is native to mountainous and semi-arid regions of southwestern Canada and the western United States, including the Rocky Mountains, Sierra Nevada, and the Great Basin, often — but not exclusively — living above 2,000 metres (6,500 feet).
It inhabits steppes, meadows, talus fields, and other open habitats, sometimes on the edge of deciduous or coniferous forests. You might also spot marmots in Wyoming’s lower-elevation foothills and open valleys, particularly where rocky outcrops provide good burrow sites.
When Do Marmots Hibernate in Wyoming
Marmots in Wyoming are true hibernators — not light sleepers that occasionally stir like bears, but animals that undergo a profound physiological shutdown for months at a time. Understanding when they go in helps you understand when to expect them back out.
To survive the frigid winters of western Wyoming, these marmots go into power-saving mode: according to the National Park Service, yellow-bellied marmots will hibernate from autumn through early spring. More specifically, they enter their burrows in September to early October and don’t emerge again until the following April or May.
Yellow-bellied marmots spend about 80% of their lives in their burrows, 60% of which is spent in hibernation. That’s a remarkable commitment to sleep.
- Hibernation start: Late September to early October
- Hibernation end: April to early May (elevation-dependent)
- Total duration: Approximately seven to eight months
While in the hibernation state, a marmot’s body temperature can drop to approximately 41°F, and its heartbeat dips to about 30 beats per minute, down from the 180 to 200 range of its active heartbeat. The mammals also take just one to two breaths per minute.
Pro Tip: Marmots are among the true hibernators of the Greater Yellowstone Ecosystem, a list that also includes ground squirrels and bats. Other mammals colloquially known as hibernators actually enter a state called torpor, which is similar to hibernation but not as intense or lengthy. Bears, for example, enter torpor for a few months to survive a harsh winter, but they can still occasionally wake up. You can read more about how bear hibernation differs from what marmots experience.
Although they hibernate, marmots do not store food for the winter. Much of their active season is spent accumulating enough fat to survive hibernation. In fact, when marmots hibernate, they undergo metabolic suppression. Their body temperature drops to 41 degrees Fahrenheit, just above freezing, and their body fat drops up to a gram per day.
When Do Marmots Come Out of Hibernation in Wyoming
This is the question most Wyoming wildlife watchers find themselves asking each spring. The short answer: April through early May, depending largely on elevation and snowpack.
The hibernation period varies on elevation, but it is typically from September to May. Marmots at lower elevations in Wyoming’s foothills and valleys may stir earlier, while those in the high alpine zones of the Wind River Range or the Absarokas tend to stay underground longer.
Marmots emerge through the snow in April and early May, during which time there may be nothing to eat, and when they are especially vulnerable to predators. This can be a surprisingly risky moment for them — the snow hasn’t fully melted, food is scarce, and hungry coyotes and golden eagles are watching.
Males usually exit a few days earlier than females in late March, April, or sometimes in May. This head start gives males time to establish territory and locate females before the brief mating window opens.
Important Note: Due to their high-altitude environment, marmots are particularly vulnerable to the effects of climate change. Increasing temperatures have shifted the seasonality of marmot behavior, causing hibernation season to end sooner, and breeding season to start sooner. Emergence dates in Wyoming may shift slightly earlier in unusually warm springs.
Marmots will emerge having lost approximately one half their fall body weight. That dramatic weight loss is one of the reasons their first priority after waking is finding food — though snow often makes that difficult in the earliest weeks of emergence.
| Elevation Zone | Typical Emergence Window | Example Wyoming Locations |
|---|---|---|
| Lower foothills / valleys | Late March – early April | Basin areas, lower canyon edges |
| Montane / subalpine | Mid-April – late April | Yellowstone valleys, lower Tetons |
| High alpine | Late April – mid-May | Wind River Range, upper Absarokas |
What Marmots Do Immediately After Hibernation in Wyoming
Waking up from seven or eight months of near-total metabolic shutdown is no small thing. Marmots don’t simply pop out of the ground and go about their day — their first weeks above ground follow a fairly predictable sequence driven by survival and reproduction.
Mating comes first. Mating generally occurs within the first two weeks following emergence from hibernation. Males that emerged slightly ahead of females use that window to visit neighboring burrows and establish breeding opportunities. This is mating season, and males may move from hibernacula to hibernacula visiting females in their harem.
Then comes eating. Once the snow melts, marmots eat. They are herbivores and eat a variety of grasses and forbs. Eating is important because they must double their mass during the year to ensure survival through the next winter. That’s an extraordinary amount of weight to gain in just a few months of activity.
According to Yellowstone, their diet consists of grasses and forbs in early summer, seeds in late summer, and occasionally insects.
Pro Tip: Yellow-bellied marmots normally appear from burrows soon after sunrise, defecate, and spend time grooming and sunning. They forage by mid-morning, followed by sunning, grooming, and long intervals in the burrow. They feed again by late afternoon. Most time spent above ground involves sunning with head in an alert position. This daily rhythm makes mid-morning and late afternoon your best windows for observation.
Pups arrive in late spring. Gestation is about 32 days, and mothers nurse their young in their natal burrows for about another month before the pups emerge above ground. Pups, which emerge in late June through late July, must more than double their emergence mass to have a good chance of survival.
Vigilance is constant. To deal with predators — which include coyotes, raptors, and bears — marmots have a sophisticated set of antipredator behaviors. They allocate time to anti-predator vigilance and modify their vigilance according to the riskiness of a location. That upright, alert posture you’ll often see on a boulder isn’t just cute — it’s a survival strategy. You can learn more about how bears emerging from hibernation can affect prey species like marmots in mountain ecosystems.
When hibernating yellow-bellied marmots emerge in spring, they are the same age, biologically speaking, as when they first curled up in their dens eight months ago. Research suggests that hibernation may actually slow the aging process at a cellular level — one of the more fascinating aspects of marmot biology.
Where to Spot Marmots in Wyoming
Wyoming offers some of the best marmot-watching opportunities in the American West, particularly in its national parks and mountain ranges. Knowing the right habitat and the right locations gives you a significant advantage.
Habitat to look for: Marmots are commonly found in rocky outcrops and talus fields at higher elevations. These areas offer plenty of nooks and crannies for shelter and burrowing. Alpine meadows adjacent to these rocky areas provide rich foraging grounds during the summer months.
In addition to alpine habitats, marmots also inhabit subalpine and montane zones. Here, they can be found near forest edges and in open grassy areas where they can feed on a variety of plants.
Top locations in Wyoming:
- Yellowstone National Park: Yellow-bellied marmots are widely dispersed in Yellowstone National Park and prefer landscapes with lots of thick grass and rocks. Reliable sighting spots include Storm Point, the Yellowstone River Picnic Area Trail, the area around Natural Bridge, and a marmot colony in a rock hill across the road from Sedge Bay.
- Grand Teton National Park: Animals found throughout Grand Teton National Park include marmots, particularly in rocky, high-elevation terrain. Death Canyon, located in the southern part of Grand Teton National Park, is another good spot for marmot sightings.
- Gros Ventre Range: The rugged terrain of the Gros Ventre Range provides ideal habitat for marmots. Jackson Hole, Wyoming, is a treasure trove of wildlife, with the charming and curious Wyoming marmot being one of its lesser-known but equally fascinating residents.
- Bear Lodge Mountains (Northeast Wyoming): Part of the Black Hills National Forest, the Bear Lodge Mountains in Northeast Wyoming provide a gorgeous playground for both human visitors and a diverse array of animals. The town of Sundance makes a great base camp for exploring the rugged landscape and looking for mountain goats, bighorn sheep, elk, mule deer, marmots, and more.
- Beartooth Pass: If Beartooth Pass is in your itinerary, there are quite a few marmots in certain areas at the top of the pass.
Pro Tip: Rocky, alpine slopes and rock piles make good homes for marmots. They graze on grass and other vegetation during the day. If it’s extremely warm, however, a marmot will take shelter in its burrow. On hot summer afternoons, you may find burrow entrances that appear empty — try again in the cooler early morning or late afternoon hours.
If you’re planning a broader Wyoming wildlife trip, it’s also worth knowing when other animals become active. Snakes in Wyoming follow their own seasonal emergence timeline that often overlaps with marmot activity in the foothills.
How to Tell If a Marmot Is Active in Wyoming
Even when marmots are present in an area, they can be easy to miss if you don’t know the signs. Here’s what to look and listen for when you’re out in marmot country.
Listen for the whistle. Marmots communicate with each other through a high-pitched whistle. Depending on how sharp the whistle, colony members respond by either observing their surroundings or returning to their burrows. That sharp, piercing call is often your first clue that a marmot is nearby — and that it’s already spotted you.
To warn each other of predator danger, marmots will emit a loud whistle or scream, which earned them the nickname “whistle pigs.” Early Wyoming explorers used this nickname widely, and it still fits.
Look for burrow entrances. About 10 to 12 inches in diameter, the entrances to marmot burrows can be identified by the large mounds of dirt the pests excavate as they dig. These mounds are also common places to spot marmots sitting when aboveground. Fresh dirt around a burrow opening is a strong indicator of recent activity.
Watch for sunning behavior. Daily activities of marmots consist of grooming, sunning, feeding, digging, and residing in their burrows. Marmots typically start their day by emerging from their burrows. They then groom each other and lay in the sun before feeding. A flat boulder facing south or southeast — one that catches the morning sun — is worth watching carefully.
Check the season. Yellow-bellied marmots are diurnal and are less active during the night. If you’re visiting Wyoming between May and August, you’re in the heart of marmot activity season. By late September, most have already retreated underground for another long winter.
Common Mistake: Many visitors scan only the ground for marmots and miss them entirely. Marmots frequently perch on top of large boulders and rocky outcrops to survey their surroundings. Train your eyes to check elevated rock surfaces, not just the ground level, especially near talus fields and cliff edges.
Note the social dynamics. Like many marmot species, the yellow-bellied marmot is a highly social animal. Yellow-bellied marmots demonstrate social behaviors including the visiting of burrows, greeting of colony members, and play-fighting. Spotting one marmot often means others are nearby — look around the same rocky outcrop for additional individuals.
Marmots are one of Wyoming’s most rewarding wildlife encounters precisely because they’re approachable, active during daylight, and reliably found in some of the state’s most beautiful mountain landscapes. Whether you’re hiking a trail in Grand Teton, driving through Yellowstone, or exploring the Wind Rivers, knowing when and where to look puts you in a much better position to find them. Plan your visit for May through August, keep your eyes on the boulders, and listen for that unmistakable whistle — it’s one of the most distinctive sounds in the Wyoming high country.