Olympic marmot (Marmota olympus)

Physical description

The Olympic marmot has brownish fur interspersed with white. Their total length is about 18 to 32 inches with a tail that is about 6 to 10 inches long. They  weigh between 9 to 20 pounds. 

Ecology and life history

The Olympic Marmot inhabits subalpine and alpine meadows and talus slopes at elevations from 920 to 1,990 meters. Its range is largely contained within Olympic National Park.

Typical habitat for Olympic Marmots encompasses subalpine and alpine meadows and talus slopes near timberline at elevations from 300 to 6500 feet. Many colonies are located on south-facing slopes, where food availability is probably greater because of earlier snowmelt. The proximity of nearby suitable meadow habitat may be a limiting factor for colonization or recolonization of vacant habitats. Suitable meadow habitat is naturally fragmented, being distributed in discontinuous patches of varying quality and size (from 12 to more than 250 acres) across exposed mountain slopes.

Olympic Marmots are gregarious and form colonies ranging in size from a few to more than 40 animals. Marmots dig burrows that are used for shelter throughout the year. 

Diet is comprised of herbaceous plants, roots, and woody vegetation. The species hibernates without eating or drinking for seven to eight consecutive months from fall to late spring, relying on accumulated body fat and a much reduced metabolism.

Olympic marmots have a long maturation period, low rate of reproduction, and high juvenile mortality. They are not reproductively mature until 3 years of age, and the average age of females at first reproduction is four and one half years. Only about 30 percent of adult females produce litters in any given year. Litters range in size from one to six pups and are born in underground burrows. Juvenile mortality during the first year is about 50 percent. Marmots can live into their teens.

Young females are fairly sedentary and rarely disperse within about a 1000 feet to establish new home ranges.

Predation by coyotes, not present prior to the 20th century, was the most common cause of mortality for adult females from 2002 to 2006. Coyotes have reportedly inhabited high elevation areas of the Olympic Peninsula for around 60 years, but were rare or absent from the Olympics historically when wolves were widespread in western Washington.

Geographic range

Olympic marmots are endemic to the Olympic Mountains. Localized declines and extirpations have occurred since the late 1980s, while numbers at some sites have remained stable.

Olympic marmots were numerous during a three-year study in the 1960s, but in the late 1990s rangers began noticing many long-occupied meadows no longer hosted marmots.

Predation by coyotes was the most common cause of mortality. The decline in the marmot population during the 1990s and early 2000s, followed by an increase in marmot survival in years with higher snowpack, suggests that coyote predation is affected by snowpack. If this relationship is confirmed, it indicates Olympic marmots will be affected by any decline in average snowpack resulting from climate change.