The Alaska marmot has winter dens plugged with dirt, vegetation, and feces from around September to June.
Alaska marmots, also called Brooks Range marmots, inhabit rocky mountain slopes and scree fields in northern Alaska. Their winter dens are permanent structures that may be reused for many years. A colony seals the single entrance before the long Arctic winter, creating a sheltered environment for communal hibernation.
The plug is made from a mixture of dirt, vegetation, and feces. It helps close the entrance against cold and snow while the marmots remain inside. The dens are often built on exposed ridges that thaw earlier than surrounding ground; the plug melts in spring, allowing the colony to emerge. Although the hibernation period is commonly described as September to June, the exact timing varies with snowfall, temperature, and local conditions.
Alaska marmots should not be confused with hoary marmots, another species found in Alaska. The Alaska marmot lacks the hoary marmot’s distinctive white facial patch and is concentrated mainly in the Brooks Range.