Montana’s mountains hold a quiet secret all winter long: tucked beneath boulder fields and talus slopes, marmots are sleeping through months of cold and snow. These chunky, charismatic rodents spend more of their lives underground than almost any other mammal in the state, and knowing when they finally resurface can completely change the way you experience a hike in the high country.
Whether you’re hoping to spot one sunning itself on a rock at Glacier National Park or simply want to understand the rhythms of Montana’s alpine wildlife, this guide walks you through everything you need to know — from which species live here to exactly when they come out and where to find them.
Key Insight: Montana is home to two marmot species, and their emergence timing differs based on elevation. Knowing which one you’re looking for helps you plan your outing more precisely.
Which Marmot Species Live in Montana
Although there are 14 marmot species worldwide, only two inhabit Montana — the hoary marmot and the yellow-bellied marmot. Each occupies a distinct ecological niche in the state, and understanding the difference between them makes it much easier to know where and when to look.
The hoary marmot (*Marmota caligata*) is a species that inhabits the mountains of northwest North America, living near the tree line on slopes with grasses and forbs to eat and rocky areas for cover. It is the largest North American ground squirrel and is often nicknamed “the whistler” for its high-pitched warning call issued to alert other members of the colony to possible danger.
You can distinguish the hoary marmot from Montana’s other marmot, the yellow-bellied marmot, fairly readily based on color — the hoary marmot is whitish gray and grizzled, whereas the yellow-bellied marmot is yellowish brown to tawny with a distinctly yellow belly. The hoary marmot is the larger of the two species.
| Feature | Hoary Marmot | Yellow-Bellied Marmot |
|---|---|---|
| Scientific Name | Marmota caligata | Marmota flaviventris |
| Coloration | Whitish gray and grizzled | Yellowish brown, yellow belly |
| Size | Larger (up to ~20 lbs) | Smaller (~10 lbs) |
| Preferred Elevation | High alpine and subalpine | Valley bottoms to alpine tundra |
| Montana Range | Western Montana (alpine) | Statewide where habitat exists |
| Nickname | “The Whistler” | “Rock Chuck” |
Where their ranges overlap, hoary marmots are found in alpine habitats and yellow-bellied marmots at lower elevations. Yellow-bellied marmots occur from valley bottoms to alpine tundra where suitable habitat exists, but where *Marmota caligata* occurs, *M. flaviventris* is restricted to lower elevations.
The hoary marmot species is common to uncommon in alpine meadows and associated subalpine habitat across western Montana. If you’re exploring the Rocky Mountains near Glacier National Park or the Bob Marshall Wilderness, you’re likely in hoary marmot territory. Yellow-bellied marmots, by contrast, can turn up across a wider swath of the state wherever rocky outcrops and open meadows come together.
Pro Tip: Listen for a sharp, high-pitched whistle echoing across a talus field — that’s often your first clue a marmot is nearby, even before you spot one.
When Do Marmots Hibernate in Montana
Marmots are among the most dedicated hibernators in North America. Using the traditional definition of hibernation, the largest marmots are considered the largest “true hibernators,” since larger hibernators such as bears do not have the same physiological characteristics as obligate hibernating animals. For Montana’s marmots, this means a winter sleep that is deep, long, and metabolically remarkable.
The hoary marmot spends the majority of its life hibernating. In Montana, hoary marmots hibernate from September to early May. Yellow-bellied marmots hibernate for approximately eight months starting in September and lasting through the winter. Both species typically begin preparing for hibernation in late summer, gorging on plants to build up fat reserves before retreating underground.
Hibernation involves bouts of deep torpor — where marmots maintain a body temperature just a few degrees above the ambient temperature in their burrow — and periodic arousal, where they arise and urinate before going back into a deep torpor bout. During the depths of winter, deep torpor bouts can last up to about two weeks, while in spring the bouts become shorter and body temperature rises. Hibernation is remarkably efficient during winter — marmots burn almost nothing.
During hibernation, a marmot’s heartbeat slows to just 3–4 beats per minute, compared to an average range of 110–200 beats per minute when they are active. Snow depth plays a critical role in their survival during this period. The deep snow that piles up over their burrows acts like a white blanket, keeping the ground warmer when air temperatures above the snow get extremely cold. A low-snow year means a thinner blanket for keeping the marmot’s burrow from freezing.
Important Note: Marmots do not store food for winter. They survive entirely on fat accumulated during the active season, which is why late-summer foraging is so critical to their survival.
If you’re curious how Montana’s other hibernating wildlife compares, you can read about when bears come out of hibernation in neighboring Idaho, where similar alpine conditions shape the seasonal calendar.
When Do Marmots Come Out of Hibernation in Montana
This is the question most visitors and wildlife watchers want answered, and the timing depends on which species you’re watching and what elevation you’re at.
For hoary marmots, Montana records show hoary marmots hibernating from September to early May, meaning emergence typically begins sometime in May once conditions at high elevations allow. Yellow-bellied marmots, living at lower elevations with earlier snowmelt, tend to emerge somewhat sooner — often in April or early May in many parts of the state.
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 early emergence while snow still covers the ground is driven largely by reproductive pressure rather than food availability.
The exact timing may vary from one year to another and from one site to another depending on snow conditions, and can also vary from one individual to another. A heavy snow year will delay emergence at high-elevation sites; a warm, dry spring may pull marmots out of their burrows earlier than usual.
- Yellow-bellied marmots (lower elevations): Typically emerge April through early May
- Hoary marmots (high alpine): Typically emerge May, with some sites as late as mid-May
- Timing variable: Snow depth, elevation, and annual weather conditions all influence the exact date
- Males first: Adult males generally emerge before females and juveniles
Adult males emerge earlier than females and juveniles. This pattern is consistent across marmot species and is tied to the mating system — males need to establish themselves and begin seeking mates as soon as possible after the long winter.
Increasing temperatures have shifted the seasonality of marmot behavior, causing hibernation season to end sooner and breeding season to start sooner in recent decades. This means the traditional April–May emergence window may continue to shift earlier over time as Montana’s climate warms.
Pro Tip: If you’re planning a trip to see marmots in Glacier National Park’s high alpine zones, aim for late May through June when snow has partially melted and marmots are highly active near their burrow entrances.
What Marmots Do Immediately After Hibernation in Montana
Waking up from months of deep torpor is no small feat. When marmots first emerge in spring, their bodies are depleted and the landscape around them may still be largely snow-covered. Their behavior in the first days and weeks after emergence is shaped entirely by two urgent priorities: reproduction and rebuilding fat reserves.
Immediately after marmots emerge from hibernation, reproductive activity begins. Gestation is about 30 days, with an average litter size of 2–4. For hoary marmots, the litter of two to five young is born between late May and mid-June. For yellow-bellied marmots in Montana, litter emergence occurs from mid-June to early August.
Foxes and coyotes have been observed waiting outside snow tunnels from hibernacula to prey on emerging marmots. Despite this danger, it is mating season and males may move from hibernacula to hibernacula visiting females in their harem. The drive to mate overrides the risk of predation in these first weeks.
Once the snow begins to recede and vegetation becomes accessible, feeding becomes the dominant activity. Once the snow melts, marmots eat. Eating is important because they must double their mass during the year to ensure survival through the next winter. Emerging earlier to find no food causes marmots to lose a lot of mass, making spring a costly and challenging season.
You’ll also notice a lot of social activity in the days following emergence. Many forms of social behaviour have been observed among hoary marmots, including play fighting, wrestling, social grooming, and nose-to-nose touching. After months of isolation underground, colonies re-establish their social bonds quickly.
Sunbathing is another key post-hibernation behavior. Hoary marmots frequently sun themselves on rocks, spending as much as 44% of their time in the morning doing so. This thermoregulatory behavior helps them warm up efficiently after the cold of their burrows and is one of the most reliable signs that a marmot is fully active.
Common Mistake: Assuming a marmot seen in early spring is fully settled into its active routine. In the first week or two after emergence, marmots may disappear back into their burrows for extended periods as their bodies adjust to being awake.
If you’re interested in comparing spring emergence patterns across Montana’s wildlife, our guide on when snakes come out in Montana covers another species whose activity closely tracks seasonal temperatures.
Where to Spot Marmots in Montana
Montana offers some of the best marmot-watching opportunities in the lower 48 states, particularly in its northwestern mountain ranges. Knowing the right habitat and locations puts you in a much better position to find these animals.
Hoary marmots occupy alpine and subalpine habitats, with burrows in rock outcrops, boulder fields, or talus slopes adjacent to meadows. Yellow-bellied marmots are similarly tied to rocky terrain. They inhabit talus slopes or rock outcrops in meadows, preferring areas with abundant herbaceous and grassy plants nearby. Rocks support their burrows and serve as sunning and observation posts. They avoid dense forests.
Top locations for marmot watching in Montana:
- Glacier National Park: Glacier and the Canadian parks are home to hoary marmots. Lucky and observant visitors can see them in various locations around the park, but the alpine meadows behind the Logan Pass Visitor’s Center are a good place to look. Marmots can be spotted from low valleys to alpine areas. Logan Pass is a great place to start your search — they are usually in open, grassy communities and almost always near rocks.
- Beartooth Plateau: The high-elevation plateau along the Montana-Wyoming border provides extensive talus and alpine meadow habitat. Both species have been documented here, with historical records of yellow-bellied marmots on the plateau going back to the mid-20th century.
- Bob Marshall Wilderness: Remote and rugged, this wilderness area in western Montana supports hoary marmot populations in its upper alpine zones. Reaching them requires effort, but the solitude makes the experience rewarding.
- Mission Mountains: The steep terrain west of the Flathead Valley offers accessible alpine zones where hoary marmots are regularly observed.
Western Montana represents the southern extent of the hoary marmot’s distribution, making it a particularly interesting place to observe this species. Hoary marmots are considered an ideal indicator of rapid environmental change in alpine areas because of their sensitivity to environmental conditions.
Pro Tip: The best time of day to spot marmots is morning, when they emerge from their burrows to warm up on exposed rocks. They are typically active in the morning, late afternoon, and evening. Midday activity drops off, especially in warm weather.
For those planning wildlife-watching trips across the region, it’s worth noting how marmot emergence timing compares to other hibernating species. You can explore when bears emerge from hibernation in Colorado or when bears come out in California to see how elevation and latitude shape these seasonal patterns across the West.
How to Tell If a Marmot Is Active in Montana
If you’re out in the field and want to know whether marmots in an area are up and moving, there are several reliable signs to look for — both visual and auditory.
Auditory signs:
Hoary marmots are vocal animals, with at least seven distinct types of calls, including chirps, whistles, growls, and whining sounds. Many of these calls are used as alarms, alerting other animals to potential predators. If you hear a sharp, piercing whistle echoing across a rocky slope, there’s a very good chance an active marmot has spotted you before you spotted it.
Visual signs:
- Sunbathing on rocks: One of the most reliable indicators. Marmots spend most of their mornings soaking up the sun rays, and a marmot draped across a boulder in the morning light is a classic sight in Montana’s high country.
- Fresh digging around burrow entrances: Loose soil or debris freshly pushed from a burrow opening is a strong sign of recent activity, especially in spring when marmots first emerge.
- Scent marking on rocks: Marmots communicate using scent, both by defecation and by marking rocks or plants using scent glands on their cheeks. Worn, darkened patches on prominent boulders can indicate a frequently used lookout post.
- Upright sentinel posture: An active marmot standing tall on its hind legs, scanning the surroundings, is one of the most distinctive wildlife sightings Montana has to offer.
In areas frequented by people, hoary marmots are not shy. Near well-traveled trails like those around Logan Pass in Glacier, you may find marmots that barely react to hikers passing nearby. In more remote terrain, they tend to be more wary and will retreat to their burrows at the first sign of disturbance.
Key Insight: Absence of marmots doesn’t always mean the area is unoccupied. Marmots avoid temperature stress by adjusting the amount of time they are active aboveground. On average, yellow-bellied marmots are active for 74% of the time from sunrise to 10:00 a.m., dropping to 43% from 10:00 a.m. to 4:00 p.m. A quiet midday site may be full of marmots that are simply resting underground.
Climate change is an important backdrop to all of this. Marmot populations are vulnerable to climate change because their physiology is adapted to low temperatures and they are stressed by high heat loads. Species like the hoary marmot that live in high alpine areas are most vulnerable, as they have little opportunity to move farther upslope with warming conditions. Paying attention to marmot activity in Montana’s mountains is, in a quiet way, a form of witnessing how these ecosystems are changing.
If you enjoy tracking seasonal wildlife activity across the region, explore our guides on when bears emerge in Massachusetts, when bears come out in Maine, and when snakes become active in North Dakota to see how hibernation timing shifts across different climates and latitudes.