Microtus miurus Osgood 1901

131.

Singing Vole

Microtus miurus

French: Campagnol chanteur / German: Alaska-Wihimaus / Spanish: Topillo fonador

Other common names: Alaska Haymouse, Alaska Vole, Toklat Vole

Taxonomy. Microtus miurus Osgood, 1901, head of Bear Creek, in mountains near Hope City, Turnagain Arm, Cook Inlet, Alaska, USA.

Subspecies paneaki is considered here as a synonym of nominotypical miurus. Five subspecies recognized.

Subspecies and Distribution.

M.m.miurusOsgood,1901—KenaiPeninsula,Alaska,USA.

M.m.anderson:Rand,1945—knownonlyfromthetypelocalityinWNorthwestTerritories,Canada.

M.m.cantatorR.M.Anderson,1947—WrangellMtsofAlaska,USA,andSWYukon,Canada.

M.m.murieiNelson,1931—NAlaska,USA,andmostofYukon,Canada.

M. m. oreas Osgood, 1907 — S Alaska, USA.

Descriptive notes. Head-body 82-114 mm, tail 19-41 mm, ear 11-13 mm, hindfoot 19-21 mm; weight 22-52 g. Dorsal pelage of the Singing Vole is a mix of buff-tipped to black-tipped guard hairs and varies from pale tawny to pale buffy gray, but it is sometimes pale ocherous. Tail is darker above (dusky) and lighter buffy to ocherous below.

Habitat. Tundra and taiga-tundra ecotonal habitats on well-drained ground. Singing Voles are found most often in willows (Salix, Salicaceae) along streams or near or above tree line, with their burrows often associated with rocky outcrops and large boulders that provide structural refuge from predators. Differences in microhabitats and social interactions tend to structure ways that Singing Voles use their environment. If an area has multiple microhabitats that are strongly defined, an individual will show stronger habitat affinity, but if habitats vary less and are more uniform, behavior tends to influence how space is used.

Food and Feeding. Singing Voles are well known for communal hay piles of dried grass, shrubs, and forbs aboveground and cached food such as tubers underground for long winters. Caches are made primarily by immature individuals of the age class that is most likely to survive winter. Diet is primarily herbaceous plants and fungi, with noted affinity for feeding on horsetail (Equisetum arvense, Equisetaceae), cottongrass (Eriophorum angustifolium, Cyperaceae), coltsfoot (Petasitesfrigidus, Asteraceae), bearberry (Arctostaphylos rubra, Ericaceae), and willows. Because Singing Voles are highly social and tend to congregate at particularsites, they can have an intense localized impact on vegetation through selective feeding and from nutrients deposited in their feces.

Breeding. Breeding occurs in June-August, and litters have 4-12 young. Seasonal patterns of spatial overlap of Singing Voles that are of reproductive age suggest promiscuous mating system and some flexibility in territoriality. Males were shown to be territorial earlier in the breeding season; females tended to be territorial later.

Activity patterns. Singing Voles are active day and night and throughout the year. In winter, they are dependent on sites with adequate snow cover to avoid harsh winter conditions.

Movements, Home range and Social organization. Home ranges are hypothesized to increase with body size for males and females, with males generally having larger home ranges (average 1250 m* for adult males and 450 m?* for adult females). In a study on the north slope of the Brooks Range, Alaska, population density estimates ranged from a peak of 45 ind/ha to a low of 9 ind/ha, while a different study in the same region reported a range of 50 ind/ha to 5 ind/ ha. Highly social behavior tends to concentrate populations to localized areas and facilitates maintenance of extensive burrow systems under snow. Thought to be semi-colonial, their well-documented singing appears to be a warning signal when predators are nearby. Others have suggested, however, that vocalizations are related to territoriality.

Status and Conservation. Classified as Least Concern on The IUCN Red Lust.

Bibliography. Batzli & Henttonen (1993), Bee & Hall (1956), Douglass (1984), Hall (1981), MacDonald & Cook (2009), Maguire & Rowe (2017), Murie (1961), Musser & Carleton (2005), Rausch (1950, 1953), Wilson & Ruff (1999), Youngman (1975).