The species shows the greatest sexual dimorphism found in marmots, with adult males weighing on average 23% more than females.

The species has a diet consisting mainly of a variety of meadow flora, including dry grasses, which it also uses as bedding in burrows.

Female marmots reach sexual maturity at three years of age and produce litters of 1–6 every other mating season.

American zoologist and ethnographer Clinton Hart Merriam first formally described the Olympic marmot in 1898, as Arctomys olympus, from a specimen he and Vernon Orlando Bailey collected on the Sol Duc River.

[1][9] As of October 2011, molecular data based upon the taxonomy of the Olympic Marmot was able to approximate the initial immigration of the species from Russia to their current location of the state of Washington, also known as the trans-Beringian exchange.

[11] The Olympic marmot's head is wide with small eyes and ears; the body is stocky with stubby legs and sharp, rounded claws that facilitate digging;[12][13] the tail is bushy and ranges from 18 to 24 cm (7.1 to 9.4 in) long.

Infant marmots' fur is dark gray in color; this changes in the yearling period to grayish brown with lighter patches.

The first molt of the year occurs in June, commencing with two black patches of fur forming on the back of the shoulders.

[23] Marmots are in decline in some areas of the park due to the encroachment of trees into meadows as well as predation by coyotes, and they are seldom seen in the wetter southwestern part.

[24] Within the park, Olympic marmots inhabit lush sub-alpine and alpine meadows, fields, and montane scree slopes.

[25] They live in colonies spread out in various locations in the mountains and containing the burrows of differing numbers of marmot families.

There is a higher risk of inbreeding and death from random events in meadows with fewer marmots, making migration essential to the survival of the species.

[1] Burrows are more frequently located on south-facing slopes, which generally receive more precipitation, 75 cm (30 in) per year (mostly snow), and thus have more available flora.

[18] The Olympic marmot is well-adapted to its generally cold natural habitat, where there is snowfall almost every month of the year on the mountain slopes and barren grasslands.

[26] Olympic marmots eat meadow flora such as avalanche and glacier lilies, heather blossoms, subalpine lupine, mountain buckwheat, harebells, sedges, and mosses.

[28] When snowfall covers vegetation, marmots have a more carnivorous diet, consuming carrion encountered while digging for roots and possibly killing late hibernating chipmunks (Neotamias townsendii).

[1][18] The Olympic marmot's predators are mostly terrestrial mammals such as coyotes, cougars, and bobcats;[30] however, it is also preyed on by avian raptors such as golden eagles.

[33] An additional behavior that takes place when a marmot becomes nervous or bothered by a predator is that it retracts its top lip to show its upper incisors.

When researchers intrude on colonies to observe behavior, the families living in burrows there initially vocalize ascending calls, showing surprise, but later adjust to the presence of humans, allowing studies to proceed.

In between these times, Olympic marmots can sometimes be found lying on rocks where they sun themselves for warmth, grooming each other, playing, chirping, and feeding together.

The diminution of hostile behavior is only temporary, as the satellite male becomes assigned to its subordinate status again the following spring after emergence from hibernation and the ritual begins again.

A gland located in their cheek exudes chemicals which they rub on scenting points, such as shrubs and rocks, which can be smelled by other marmots in the area.

Sometimes they are so disoriented after awaking from hibernation that they have to relearn the colony's landmarks (which are now covered in snow, which obscures them even more); they wander around aimlessly until they find their burrows.

After hibernation ends, both male and female Olympic marmots attempt to entice the opposite sex with courtship rituals.

[2] Even after they are allowed to emerge, the young initially stay within the immediate vicinity of the burrow, where they can be found chasing each other and wrestling playfully.

In 1989, the total Olympic marmot population was calculated to be only about 2,000, but this low number was due to poor data collection.

Predation by coyotes that had not been present in the area before the 20th century was found to be the main cause of death of females, inhibiting population re-growth.

[18] The park, which holds multiple other endemic species, has been designated a UNESCO Biosphere Reserve and a World Heritage Site.

"[50] Governor Chris Gregoire's signing of Senate Bill 5071 was the result of a two-year effort by the fourth and fifth graders of Wedgwood Elementary School in Seattle.

The students researched the marmot's habits, and answered legislators' questions to overcome initial bipartisan opposition to another state symbol.