Download Microtus ochrogaster

Kevin Luepke
Microtus ochrogaster
Prairie Vole
Description
The pelage of a Prairie vole is most often dark brown to black along the head and back.
Longer hairs are usually tipped with brownish-yellow, dorsally, giving a salt-and pepper
look. Ventrally, the hairs are yellowish-brown or light cinnamon. The tail is bicolor and
usually 24-41 mm long. The pelage color remains the same throughout the year. Prairie
voles have a dental formula of I1/1, C0/0, P0/0, M3/3; totaling 16. The Prairie vole can be
distinguished from other rodents by the third upper and lower molar. The third lower
molar has no closed triangles and three transverse loops. The third upper molar has two
closed triangles. Five plantar tubercles are found on the hind feet and females have three
sets of mammary glands in the Prairie vole. Adults have a total length ranging between
125 and 172 mm, tail length of 24 to 41 mm, hind foot length of 17 to 22 mm, ear length of
11 to 15 mm, and weight between 30 and 60 g (Kurta 1995, Stalling 1990).
Distribution
There are 6 subspecies of Microtus ochrogaster currently recognized with 2 species found
in Wisconsin: Microtus ochrogaster minor is found in the central part of the state and
Microtus ochrogaster ochrogaster, is found in the southern part of the state (Stalling
1990).
Microtus ochrogaster ranges from southeastern Alberta, Canada; to western West
Virginia; to northern Alabama; to northeastern New Mexico; and back up to southeastern
Alberta, Canada (Kurta 1995, Stalling 1990). Recently, the range of the Prairie vole has
increased on the south and east margins of its range, due to clearing forests, floodplains,
and ditch-lines of railways and roadways which serve as corridors for dispersal (Stalling
1990).
Figure 1. Distribution of subspecies of Microtus ochrogaster
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Microtus ochrogaster haydenii
Microtus ochrogaster ludovicianus (extinct)
Microtus ochrogaster minor
Microtus ochrogaster ochrogaster
Microtus ochrogaster ohionensis
Microtus ochrogaster similis
Microtus ochrogaster taylorii
(Figure 1. taken from Stalling 1990).
Reproduction
The Prairie vole is monogamous, a female and male share the same nest and home range,
and remain together for life. Males exclude other males from the home range through
aggression. Both, mother and father, care for the young. Prairie voles breed during the
spring, summer, fall, and mild winters. Lowest levels of reproduction occur between
December and January, where as the highest reproductive activity takes place between
May and October. The Prairie vole shows a cyclic change in population density (90%
change between high and low) of 2 to 4 years. Gestation lasts on average 21 days, when
three to four young, weighing 3 g, are born with closed eyes and ears, and digits fused 75%.
Fur appears on young by day 2, crawls by day 5, begins eating solid food by day 12, and is
weaned between 2 and 3 weeks. Maternal age, size, and time of the year affect the litter
size. Most of the growth of a Prairie vole is complete by 2 months. Females mature in
30-40 days and males mature at 35-45 days (Kurta 1995, Stalling 1990). The average life
span of Microtus ochrogaster is one year, but can live up to two years of age (Stalling
1990).
Behavior
Microtus ochrogaster is a crepuscular mammal. Activity occurs during sunrise and sunset,
although activity changes throughout the seasons. Diurnal activity decreases during
summer, and increase during the winter. Communal groups that are formed, are usually
made of offspring and survivors from the past winter and are broke down into social
organization (Lanctot 1999, Cochran 1999). Aggressive behavior was found when food
and water were competed for, and when home ranges were overlapping (Lanctot 1999).
Microtus Ochrogaster is mostly herbivorous, feeding on grass mainly, alfalfa, dandelion,
fleabane, plantain, and clover. Also, insects and few fruits in the summer and autumn, and
moss, bark, and roots during the winter and early spring. Seeds contribute to the diet
year-round (Kurta 1995, Stalling 1990). Microtus ochrogaster is a grassland loving
species, which inhabits drier sites with shorter and more varied plant vegetation in the
Great Lakes region due to habitat competition with the meadow vole (Kurta 1995). In the
rest of the distribution of Prairie voles, they are found in ungrazed pastures, fallow fields,
weedy areas, fencerows, ditch lines, and occasionally in cultivated fields of alfalfa or
soybeans (Stalling 1990). The home range of a Prairie vole is relatively small, about ¼
acre (0.1 ha). A network of runways are constructed through the grass, which come from
feeding areas leading to burrow entrances, which creates a grass canopy to protect against
predation. A burrow is shallow, and used for feeding, cashing food, or a nest of dried grass
during the winter, and aboveground during the summer. The Prairie vole makes up a
portion of the diet of many carnivorous mammals, raptors, and retiles. Such as the coyote,
red fox, house cat, opossum, least weasel, short-tailed shrew, Cooper’s hawk, red-tailed
hawk, barred owl, screech owl, shrike, and various snakes (Kurta 1995). Monogamous
relationships are found, because strong pair bonds are formed between the mates, and this
isn’t seen in the female until after she has mated, also, biparental caring of young (Stalling
1990, McGuire et al. 2002). The Prairie vole is found living in small family groups, older
pups care for neonatal siblings (Kurta1995). Pups and neonatal infants are able to emit
ultrasounds, which aid in helping the parents find them for thermoregulatory needs (Blake
2001).
Literature Cited
Blake, B. H. 2001. Ultrasonic calling in isolated infant prairie voles (Microtus
ochrogaster) and montane voles (M. montanus). Journal of Mammalogy,
83(2):536-545.
Cochran, G. R., N. G. Solomon. 1999. Effects of food supplementation on the social
organization of prairie voles (Microtus ochrogaster). Journal of Mammalogy,
81(3):746-757.
Kurta, A. 1995. Mammals of the Great Lakes Region. The University of Michigan
Press, Ann Arbor, Michigan, USA.
Lanctot, R. B., L. B. Best. 1999. Comparison of methods for determining dominance
rank in male and female prairie voles (Microtus ochrogaster). Journal of
Mammalogy, 81(3):734-745.
McGuire B., E. Henyey, E. McCue, W. E. Bemis. 2002. Parental behavior at parturition
in prairie voles (Microtus ochrogaster). Journal of Mammalogy, 84(2):513-523.
Stalling, D. T. 1990. Microtus ochrogaster. Mammalian Species 355:1-9.
Reference written by Kevin Luepke, Biol 378: Edited by Chris Yahnke. Page last updated