Nuzzling, playing, chirping, feeding together; the Olympic marmot is quite possibly one of the most social and gregarious mammals on the peninsula. They are endemic to the Olympic Peninsula, meaning they are found no where else in the world. The Olympic marmot is a housecat-sized rodent with a long, bushy tail. Adults can weigh 15 pounds or more before they enter hibernation in September or early October. They are often brownish in color, but may be yellow or tan colored when they emerge from hibernation in the spring, and almost black in the fall.
Family groups of one adult male, one or more adult females, and several cohorts of young share a home range of 1/2-acre to five acres. In any given year, about 30 percent of adult females produce litters of 1-6 pups. Pups initially stay close to their burrows when they emerge in late July, but by mid-August, they can be seen wrestling and chasing each other in enthusiastic play. Marmots have a sharp, piercing whistle that warns others of intruders or potential predators, and notifies hikers that they are in marmot territory.
Marmots occupy mountain meadows above 4000 feet. Although they are found throughout the Olympic Mountains, they are rare in the wetter southwest areas of the park. About 90 percent of Olympic marmot habitat is protected within Olympic National Park.
In the 1990s and early 2000s, Olympic marmot numbers declined,
at least partly due to predation by non-native coyotes. Marmots and their habitat are also expected to be sensitive to climate
change. In recent years, marmots have also disappeared from some of the driest meadows in the northeast Olympic Mountains. In response to these concerns, in 2010 the park initiated a monitoring program that enables volunteers to record the presence or absence of marmots in many meadows throughout the park.
Olympic marmots prefer fresh, tender, flowering plants such as lupine and glacier lilies. In May and June, they will eat roots and may even gnaw on trees. They can double their body weight in the summer and use stored fat during a seven to eight month hibernation.