Woodland Vole(Microtus pinetorum LeConte)
From: Saunders, D. A. 1988. Adirondack Mammals. State University of New York, College of Environmental Science and Forestry. 216pp.
Description: The woodland vole shows many adaptations for its burrowing lifestyle. The fur is short, soft, and silky, almost mole-like in texture. The front feet and claws are larger than those of its relatives. The eyes are small; the ears short and nearly hidden by the fur surrounding them. Characters useful in distinguishing this species from other Adirondack voles include fur color and texture, and tail length. The back and sides are auburn or chestnut; the throat, belly and feet are gray to buffy gray. The tail is about 25 mm (1.0 in) in length, slightly longer than the hind foot. Bog lemmings have shorter tails and shaggy fur; the other voles have longer tails. Woodland voles are approximately 118-130 mm (4.6-5.1 in) in total length, and weigh 20-35 g (0.7-1.4 oz).Range and Habitat: The range is most of the eastern U.S., extreme southeastern Ontario, and Southwestern Quebec. Mammal collectors have taken this species from the southeastern periphery of the Adirondack park, but records are few and the absence of the woodland vole from many small mammal surveys suggests that populations are small and widely separated. The difficulties associated with locating a small burrowing species may make this distribution more apparent than real.
Both the latin pinetorum and another common name, the pine vole, refer to a habitat this rodent occupies only in the Southeast. In the Adirondacks, it chiefly resides in deciduous and mixed forests where soils are loose and covered with a thick leaf litter. Woodland voles do not create surface runways, but dig shallow tunnels 2.5-5.0 cm (1-2 in) in diameter, that permeate the forest floor, to depths of 7.6-10.0 cm (3-4 in), occasionally deeper. Many tunnels are just under the matted layer of organic debris. Nests 15-18 cm (6-7 in) in diameter and made from dry leaves, grass, and rootlets are either a few centimeters underground or near the surface and under objects such as logs. Each nest has several openings leading to adjacent tunnels.
Food and Feeding Behavior: Woodland voles are herbivores although they occasionally eat insects and carrion. They eat a variety of herbaceous plants, but prefer grasses and sedges. The stems and underground structures (roots, rhizomes, stolons, tubers, bulbs, corms) more than green foliage form much of the summer diet, which this vole obtains by tunneling. Seeds, nuts, and fruits are major components of the autumn diet. The inner bark and small roots of woody plants, as well as plant parts and seeds cached underground during autumn, are winter foods. Where woodland voles inhabit orchards and nurseries, they are notorious for their damage to fruit trees and ornamental plants, eating roots below the snow.
Activity and Movement: Woodland voles neither climb nor swim well, and spend much of their time walking or running within the tunnel system. They excavate tunnels by loosening the soil with their front teeth and feet, kicking the particles backwards, and stooping periodically to turn around and shove the particles to the surface with their heads. Shallow mounds of soil accumulate on the surface but are often hidden under the leaf litter. Periods of activity alternate with rest throughout a 24 hour period, and at all times of the year. Winter activity occurs at the interface of snow and soil, or underground. During the remainder of the year, woodland voles are most active on the surface during the hours of darkness.
Reproduction: Breeding may take place during any month of the year, but in this region, woodland voles are more apt to breed from early spring until late autumn. Females may bear many litters, but average only 1-2 per year. The length of the gestation period is 20-24 days, and the usual litter size is 3 or 4 (extremes 1-6). At birth, a woodland voles weighs about 2.6g (0.09 oz), is blind, and apart from tiny whiskers and a few fuzzy hairs on the back, naked. The eyes open at 7-9 days, about the same age as a coat of hair and the ability to crawl vigorously develop. Weaning is complete at 17-21 days, and breeding may commence at 2-3 months. The potential life span is at least 14 months, but adults are unlikely to survive more than 2-3 months.
Predators: Some of the predators of the woodland vole are the northern harrier, red-tailed and broad-winged hawks; great horned, barred, and screech owls; red and gray foxes, mink, raccoon, and opossum.
- Social system - The mating relationships and social organization of the woodland vole are unknown. A few observations (several adults sharing the same tunnel system; three females bearing litters in a communal nest) made throughout the range suggest this vole is tolerant of its neighbors, gregarious, and possibly, monogamous. Adults of both sexes have small home ranges of 0.1-0.2 ha (0.25-0.5 acre) that overlap, and tend to remain within these home ranges or gradually shift them in response to depleted food supplies. Average densities in forested habitat are 15-25 voles per ha (6-10 per acre) and are relatively stable compared to the meadow vole. Woodland voles in orchards may exist at higher densities, in one instance estimated at 625 individuals per ha (250 per acre).
- Communication - Anal and hip glands are probable sources of products regulating social behavior, but the chemical ecology and other facets of communication are not known. The enlarges hip glands of breeding males may elicit aggressive behavior from receptive females that leads to mating. Adults vocalize in aggressive or alarm contexts, producing one to multiple-note calls often described as chattering or chirping.
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