Vancouver Island COSEWIC assessment and status report: chapter 3

• Previous page
• Table of contents
• Next page

Species Information

Name and classification

The Vancouver Island marmot (Marmota vancouverensis: Swarth 1911) is one of 14 species of marmot currently recognized (Barash 1989). It was originally described from specimens collected in 1910 (Swarth 1911, 1912).

Morphological description

Adults typically measure 67-72 cm from the nose to the tip of the tail (mean = 69.7 cm, SD = 4.0, n =68). Mass varies depending upon time of year. Adult females may increase from 3.5 kg shortly after emergence in late April to 5-5.5 kg by the onset of hibernation in early October. Mass gain is influenced by site conditions and reproductive status, but an average adult female gains 15-18 g per day during the active season. Males tend to be larger but gain mass at similar rates (Figure 1). Marmots lose approximately 30% of body mass during hibernation (Bryant and McAdie 2003).

The Vancouver Island marmot is notable for its dark chocolate fur colour and contrasting patches of white fur on the nose, belly and top of the head (Nagorsen 2005). New fur is particularly dark and almost black in young of the year. Older fur weathers to tan or cinnamon colour. Because marmots may not fully complete moulting in a given year, older animals often display a variegated fur pattern. The species also has atypical skull morphology (Cardini et al. 2005), unique vocalizations (Heard 1977), and high levels of sociality (Blumstein 1999, Blumstein et al. 2001).

Genetic description

M. vancouverensis is closely related to the hoary marmot M. caligata and Olympic marmot M. olympus, which occur on the British Columbia mainland and the Olympic peninsula of Washington State respectively (Barash 1989). Recent DNA studies (Steppan et al. 1999, Kruckenhauser et al. 1999) report limited (3-5%) genetic differences among the three species, suggesting recent divergence. Nagorsen (2005) suggested that the close affinity likely meant that marmots colonized Vancouver Island after the retreat of the Cordilleran-Wisconsin glaciers, 10,000 to 13,000 years ago.

Vancouver Island marmots display lower levels of genetic variation than other species, but are not highly inbred. Microsatellite data confirm that Mount Washington marmots are genetically isolated from those in the Nanaimo Lakes region (Table 1). There is genetic differentiation among colonies, with significant positive overall F_st=0.23 (95% range =0.09 - 0.43; Hartl 1981) mostly due to the presence of private alleles in the Mount Washington colony.