Singing Vole, Microtus miurus
The singing vole (Microtus miurus) can be found in North America. It is named so because of the high pitched warning call it gives out from the doorways of its burrow. They are native to northwestern Canada and Alaska, preferring tundra habitats above the tree line. They avoid extreme areas of these regions including the Alaska Peninsula and a large portion of the northern coast. They are found throughout the Yukon in the east and as far as the Mackenzie Mountains. They live in areas where drainage is good, like slopes and rock flats, and where vegetation is abundant. Currently, five subspecies of the singing vole are recognized.
The singing vole is medium sized, with a body length of up to 6.3 inches and a tail that can add 1.6 inches to its full length. Depending on the diet and age of the vole, it can weigh up to 2.1 ounces. The singing vole is different from other local voles because it’s under parts are not grey. Its long, soft fur often covers the small ears of the singing vole. The color of the dense fur can vary from a pale grey to pale brown and during the winter, it becomes greyer. From under the ears to the buttocks, running along the flanks, a streak of light brown can be seen on either side. The singing vole has a short tail and small, sharp claws on its feet that cannot usually be seen from underneath the fur.
Burrows of this vole contain familial groups. They are semi-colonial, and will often share burrows between family members. The burrows hold a number of chambers, used for storing food and other purposes. Each passage way is typically around .98 inches wide. This is a defense tactic that allows only vole-sized creatures to pass through, preventing possible attacks by weasels. The burrow can be as long as 3.3 feet from the entrance and can run 7.9 inches horizontally below the ground. Predators of the vole include stouts, Arctic foxes, wolverines, and hawks.
The singing vole is active during the day and night, showing no absolute preference for either time. The singing vole will create a path from the burrow to a food source, but it is not as visible as paths made from other voles. It is common for the voles to gather grasses, and leave them out to dry on rocks or on tree roots. The grasses, and sometimes horsetails or lupines, will slowly dry, creating a nutritious food source for the winter. This process starts in August, and the voles can make stacks of grass up to twenty inches high. However clever the method is, the food is still at risk of being stolen by other creatures. Singing voles will store food like roots and rhizomes (underground stems) in burrow chambers as well. Their diet consists of arctic plants like lupine, willows, horsetails, and sedges.
The breeding season for the singing vole lasts from May to September, creating enough time for each female to have up to three litters per year. Each litter typically contains eight babies, although reports have shown litters contain six to fourteen. This can be dangerous as mothers only have eight teats, and so usually, the litter will not survive. Each baby can weigh up to .09 ounces at the time of birth, but it will grow quickly within its next few weeks. At around four weeks the litter is weaned, and often times the mother is ready to mate again. Males may be ready to mate at the age of one month, while females are not usually ready until their second year. Many singing voles do not survive their first winter, but in captivity, reports have shown that they can live to be approximately 2 years old with an average lifespan of a short forty-three weeks.
Image Caption: Singing Vole (Microtus miurus), Hall Island. Credit: Morkill, Anne (US Fish and Wildlife Service)/Wikipedia