Marmota olympus

Marmota olympus formerly was regarded as a subspecies of M. marmota by some authors. It was regarded as a distinct species by Jones et al. (1992), Hoffmann et al. (in Wilson and Reeder 1993), and Thorington and Hoffmann (in Wilson and Reeder 2005). Recent genetic work suggests that Olympic Marmots diverged from the Vancouver Island (M. vancouverensis) and Hoary (M. caligata) Marmots about 2.6 million years ago (Steppan et al. 2011, Kerhoulas et al. 2015).

Small range in the Olympic Mountains of Washington State; localized declines and extirpations occurred from the late 1980s to early 2000s, but population is more or less stable at present. Coyote predation and climate change (tree encroachment into meadows) may be responsible for the declines.

The range is limited to the upper slopes of the Olympic Mountains of northwestern Washington (Edelman 2003); the species is almost completely restricted to Olympic National Park (Barash 1973). Extent of occurrence was estimated at 1,800 square kilometers by Barash (1973); survey in 2012 resulted in a mapped extent of about 1500 km2. However, the more generalized map in Cassola (2016) shows a larger extent of approximately 4500 km2. Most marmots occur at elevations of 1500-1750 meters, with normal lower and upper extremes of 920 and 1990 meters (Barash 1973, Wood 1973) and rare occurrences to near sea level (30-200 meters) (Scheffer 1995).

Based on a 5-km separation distance between occupied occurrences, there were about 12-13 mapped in the 2018 survey (NPS 2018). A few more probably exist along unsurveyed ridges.

The synergistic effects of predation by coyotes and tree encroachment into subalpine meadows may have been responsible for local declines in the 1990s and 2000s (S. C. Griffin, pers. comm., cited by Edelman 2003; Griffin et al. 2008, 2009). During the 1990s and 2000s, annual survival of adult females dropped to less than 70%, compared to about 89% in the 1960s; predation by coyotes was the most common cause of mortality (Griffin 2007, Witczuk 2007, WDFW 2013). Although coyotes have inhabited Olympic Marmot habitat for around 60 years, they were rare or absent before then, when wolves were widespread in the area (Scheffer 1995). After 2007, marmot survival increased in years with higher than normal snowpack, which apparently impacted coyote predation rates (WDFW 2013).

Climate warming and lower snowpack therefore may be linked with increased coyote predation. Warming will also cause tree encroachment in the marmot's meadows (McCaffery and Jenkins 2018), and this may be exacerbated by fire suppression.

Climate change may also alter precipitation patterns. Deep snowpack in the spring can have a negative impact on marmot reproduction, but too little snow may remove insulation needed by hibernating marmots (Inouye et al. 2000, Tafani et al. 2013) and add to drought conditions in the summer (McCaffery and Jenkins 2018).

Disturbance is not seen as a serious threat; Olympic Marmots acclimate quickly to human intrusion into colonies (Edelman 2003).