Geographic Range
Gray-tailed voles (
Microtus canicaudus
) have a limited range scattered across the northeastern United States. They are found
at low elevations throughout Willamette Valley in Oregon and at least two localities
north of the Columbia River in Clark County, Washington.
Habitat
Gray-tailed voles are associated almost exclusively with agricultural lands at low
elevations within their limited range. They have invaded formerly forested lands converted
to agriculture in coastal range valleys, adjoining the Willamette Valley. Their population
typically declines in the winter; small populations are often isolated in fragmented
habitats. Within their habitat, they construct intricate and extensive tunnels and
subterranean burrows 15 to 30 cm below the surface. They sometimes use the burrows
of other species. They use agricultural fields as a form of protection from predators
and as a food source.
- Habitat Regions
- temperate
- terrestrial
- Terrestrial Biomes
- savanna or grassland
- Other Habitat Features
- agricultural
Physical Description
This species is similar in appearance and size to their relatives,
montane voles
, except their dorsum is more yellowish, their tail is grayer and their overall pelage
is less grizzled. Their body dimensions are also close to
creeping voles
, however, their body mass may exceed 50 g, which is double that of creeping voles.
Gray-tailed voles average 145 mm in length. In the summer, they have a light yellow-brown
or yellow-gray dorsal pelage. Their venter is grayish-white and their feet are gray.
Their tail is gray beneath and brownish above. In the winter, black tipped hairs darken
their dorsum. Juveniles are gray to grayish-brown, both ventrally and dorsally, their
feet are gray and their tail is gray with a black dorsal stripe. Their skull is high,
smooth and well arched. Their incisors protrude only slightly beyond the nasals in
dorsal view and the incisive foramina are usually less than 5 mm long. Their dental
formula is I 1/1, c 0/0, p 0/0, m 3/3, total 16.
- Other Physical Features
- endothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
Reproduction
Their mating system is not definitively known. Males have some features, such as relatively
small testes, that indicate monogamy within the species. Other traits, such as their
sexual dimorphism and the larger home ranges maintained by males, indicate a polygynous
mating system. In this species, both females and males are territorial. Relatives
of the opposite sex do not keep overlapping home ranges once juveniles became sexually
active. This is thought to be an adaptation for inbreeding avoidance. Voles also have
hip glands that excrete oils used for a variety of communication functions. They possibly
function in dominance displays, individual recognition and territorial marking. While
the actual functions of these glands are not known for a certainty, they are more
functional during the breeding season.
In the laboratory setting, females as young as 18 days, weighing only 12.5 g, are
capable of mating and producing viable offspring. However, it was found that although
litter sizes were larger, the mean mass of offspring was significantly lower and offspring
survival to 18 days was significantly lower than among females that first mated at
28 days. This study also showed that up to 70 days of age, litter sizes decrease inversely
with the age at which females first mated, but a lower mass at birth is attributed
to larger litter sizes. The mean litter size found in the wild is 4.4 young. Their
breeding season is from March through December and their gestation period is 21 to
23 days. When gray-tailed voles interbreed with
montane voles
their resulting hybrid offspring generally have a significantly lower survival rate
and are generally born into smaller litters.
- Key Reproductive Features
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- viviparous
There is currently very little information available about the parental investment
of gray-tailed voles. However, parental behavior has been studied in another member
of genus
Microtus
. Among prairie voles (
Microtus ochrogaster
), both genders participate in parental care, although male participation may be limited
by female interference. It is not known whether gray-tailed voles show similar behavior
patterns.
Lifespan/Longevity
The lifespan of gray-tailed voles has not been reported. However, the captive lifespan
of other members of genus
Microtus
has been reported. For instance, woodland voles (
Microtus pinetorum
) have a captive lifespan of 3.8 years. Likewise, field voles (
Microtus agrestis
) and common voles (
Microtus arvalis
) have a known captive lifespan of up to 4.8 years. Prairie voles (
Microtus ochrogaster
) have the longest known captive lifespan within the genus at 5.3 years.
Behavior
Gray-tailed voles construct intricate and extensive systems of runways and subterranean
burrows and sometimes use the burrows of other species. These burrows are constructed
15 to 30 cm below the ground surface and range in size from 8 to 15 cm long by 3 to
5 cm wide. Nests are built underground or above ground under boards, bales and debris
scattered in fields. Heavy rains commonly flood fields for several days at a time
in the winter, so even though air trapped in subterranean nest cavities permits continued
occupancy, they must swim through flooded tunnels to reach their nest. Hybrid litters
of gray-tailed voles and other vole species result in smaller litters and fewer surviving
offspring, so interbreeding is avoided among these species.
- Key Behaviors
- terricolous
- fossorial
- motile
- territorial
Home Range
Both males and females hold territories, but male territories are larger and overlap
with many female territories. The degree of familiarity with other individuals may
influence the animal's social behavior, including their use of space and mating behavior.
It is unknown how this recognition is developed or achieved, but one proposed way
is through the oils secreted from their hip glands. Gray-tailed voles possess many
behavioral traits to avoid inbreeding. The home ranges of opposite sex relatives do
not overlap when juveniles become sexually active. Also, individuals that are familiar
with each other produce fewer litters than unfamiliar individuals.
Communication and Perception
Not much is known about communication among gray-tailed voles due to lack of experimentation.
One type of communication that is used within related vole species is oils secreted
from their hip glands. These glands are thought to function in dominance displays,
individual recognition and territorial marking. These glands have been studied minimally
within gray-tailed voles and were found to be more functional during the breeding
season. Familiarity within this species is important because it influences the animal’s
behavior, including their use of space and social behavior. Being able to recognize
kin is also a way to avoid inbreeding in this species. It is not completely known
how kin recognition is achieved or developed.
- Communication Channels
- chemical
- Other Communication Modes
- pheromones
- scent marks
Food Habits
Gray-tailed voles are primarily herbivorous. They are associated almost exclusively
with agricultural lands, especially grasses grown for seed, small grains and permanent
pastures of legumes and grasses. They commonly inhabit forage crops that provide abundant
food and cover. Hence, this species has benefited from agricultural practices. While
the specific diet of gray-tailed voles has not been studied extensively, some components
of their diet include grasses, clovers, wild onions and false dandelions. They also
thrive on white clovers, apples, bluegrasses and ryegrasses in the laboratory. Studies
looking at the predation of insects by gray-tailed voles have been inconclusive.
- Plant Foods
- leaves
- roots and tubers
- seeds, grains, and nuts
- flowers
Predation
Gray-tailed voles are countershaded, which is an anti-predator adaptation common to
many species of voles. They also avoid predators behaviorally by building underground
tunnels. Voles are also associated with agricultural fields, which provide dense cover
from predators. Some common predators of this species include owls (
Tytonidae
,
Strigidae
), hawks (
Falconidae
), foxes (
Vulpes vulpes
,
Urocyon cinereoargenteus
), skunks (
Mephitis mephitis
) and domestic and feral cats (
Felis catus
). These are common predators to many other vole species as well.
Ecosystem Roles
Mammalian associates of gray-tailed voles include vagrant shrews (
Sorex vagrans
), townsend moles (
Scapanus townsendii
), brush rabbits (
Sylvilagus bachmani
), eastern cottontails (
Sylvilagus floridanus
), California ground squirrels (
Spermophilus beecheyi
), camas pocket gophers (
Thomomys bulbivorus
), deer mice (
Peromyscus maniculatus
), dusky-footed woodrats (
Neotoma fuscipes
), townsend voles (
Microtus townsendii
), creeping voles (
Microtus oregoni
), Pacific jumping mice (
Zapus trinotatus
), long-tailed weasels (
Mustela frenata
) and striped skunks (
Mephitis mephitis
). They also host several species of fleas. In interspecific encounters with other
voles, dominant-subordinate or mutual avoidance responses generally occurred. Gray-tailed
voles use the burrows of other species, or dig their own burrows, which can be used
by other species.
- Ecosystem Impact
- disperses seeds
- creates habitat
Economic Importance for Humans: Positive
Gray-tailed voles have little known positive economic importance, outside of research.
They have been used in investigations of the impact of dietary selenium and vitamin
E on species in Oregon. They were also used as test animals to determine feasibility
of enhancing the nutritional quality of residues of annual ryegrass (
Lolium multiform
) for animal feed by fermentation with torula yeast (
Candida utilis
).
- Positive Impacts
- research and education
Economic Importance for Humans: Negative
The only known negative economic effect of gray-tailed voles is the minor damage they
cause to some agricultural crops.
- Negative Impacts
- crop pest
Conservation Status
While the population levels of this species are stable, agricultural practices such
as mowing and the use of pesticides reduce population density and growth, survival,
recruitment and body growth of these animals. Overall, though, they are thought to
have benefited due to human agricultural practices.
Additional Links
Contributors
Courtney Dibble (author), Northern Michigan University, John Bruggink (editor), Northern Michigan University, Leila Siciliano Martina (editor), Texas State University.
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- terrestrial
-
Living on the ground.
- tropical savanna and grassland
-
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
- savanna
-
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
- temperate grassland
-
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
- agricultural
-
living in landscapes dominated by human agriculture.
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- fossorial
-
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
- motile
-
having the capacity to move from one place to another.
- territorial
-
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
- chemical
-
uses smells or other chemicals to communicate
- pheromones
-
chemicals released into air or water that are detected by and responded to by other animals of the same species
- scent marks
-
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
- granivore
-
an animal that mainly eats seeds
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- tactile
-
uses touch to communicate
- chemical
-
uses smells or other chemicals to communicate
References
Boyd, S., A. Blaustein. 1985. Familiarity and Inbreeding Avoidance in the Gray-Tailed Vole ( Microtus canicaudus ). Journal of Mammalogy , 66/2: 348-352.
Dalton, C. 2000. Effects of Female Kin Groups on Reproduction and Demography in the Gray-Tailed Vole, Microtus canicaudus . Oikos , 90/1: 153-159.
Edge, D., J. Wolff, R. Carey. 1995. Density-Dependent Responses of Gray-Tailed Voles to Mowing. The Journal of Wildlife Management , 59/2: 245-251.
Gordon, D., D. Lattier, R. Salbiger, J. Torsella, J. Wolff, K. Smith. 1998. Determination of Genetic Diversity and Paternity in the Gray-Tailed Vole ( Microtus canicaudus ) by RAPD-PCR. Journal of Mammalogy , 79/2: 604-611.
Hsu, T., M. Johnson. 1970. Cytological Distinction between Microtus montanus and Microtus canicaudus . Journal of Mammalogy , 51/4: 824-826.
McGuire, B., E. Henyey, E. McCue, W. Bemes. 2003. Parental behavior at parturition in prairie voles ( Microtus ochrogaster ). Journal of Mammalogy , 84:2: 513-523.
Robbins, R. 1983. Seasonal Dynamics of Fleas Associated with the Gray-Tailed Vole, Microtus canicaudus Miller, in Western Oregon. Journal of the New York Entomological Society , 91/4: 348-354.
Schauber, E., D. Edge, J. Wolff. 1997. Insecticide Effects on Small Mammals: Influence of Vegetation Structure and Diet. Ecological Applications , 7/1: 143-157.
Tacutu, R., T. Craig, A. Budovsky, D. Wuttke, G. Lehmann, D. Taranukha, J. Costa, V. Fraifeld, J. de Magalhaes. 2013. "The Animal Aging and Longevity Database" (On-line). Human Aging Genomics Resources: Integrated Databases and Tools for the Biology and Genetics of Aging. Accessed October 11, 2013 at http://genomics.senescence.info/species/ .
Verts, B., L. Carraway. 1987. Microtus canicaudus . Mammalian Species , 267: 1-4.
Wang, G., D. Edge, J. Wolff. 2001. Rainfall and Guthion 2S Interactions Affect Gray-Tailed Vole Demography. Ecological Applications , 11/3: 928-933.
Wolff, J., D. Edge, R. Bentley. 1994. Reproductive and Behavioral Biology of the Gray-Tailed Vole. Journal of Mammalogy , 75/4: 873-879.