BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Clethrionomys rutilus | Northern Red-Backed Vole 



TIMING OF MAJOR LIFE HISTORY EVENTS : 
Breeding season - The breeding season of northern red-backed voles
generally extends from May to August.  Females are polyestrous and
produce two or three litters during the breeding season.  The first
litter is produced in late May or early June [1].

Litter size - Information regarding the gestation period of northern
red-backed voles was not available.  Litter size ranges from four to
nine.  The average litter size is 5.93 [1].

Growth of young and sexual maturity - Young northern red-backed voles
are unable to regulate their temperature successfully until about 18
days.  At this time they are weaned and leave the nest.  Young grow
little during the winter because of low food supplies.  Age of sexual
maturity depends to some extent on time of birth.  About 20 percent of
females from the first litter breed during the summer of birth.  The
remaining 80 percent, and later litters, breed the following May [1].
Martell and Fuller [12] found that the onset of summer breeding was
related to the time of snowmelt.  A late spring was followed by a low
rate of maturation of young-of-the-year females [12].

In dense populations of northern red-backed voles, sexual maturation of
young females may be delayed, or they may migrate to a vacant breeding
space [8].  Information was not available regarding sexual maturation of
male northern red-backed voles.

Behavior - Northern red-backed voles are mainly nocturnal and
crepuscular but are of necessity about during the prolonged arctic
daylight season [1].


PREFERRED HABITAT : 
Northern red-backed voles are commonly found in northern shrub
vegetation or open taiga forests.  They also inhabit tundra [1,12,21].
Northern red-backed voles are abundant on early successional sites as
well as in mature forests [21].  They occasionally inhabit rock fields
and talus slopes [1].

Northern red-backed voles use surface runways through the vegetation as
travel corridors.  Nests are built in short underground burrows or under
some protective object such as a rock or root [1].  Northern red-backed
voles are active all winter and construct long tunnels under the snow.
Winter nests typically are placed on the ground among thick moss [1,21].
Northern red-backed voles frequently invade houses during the winter
[1].


COVER REQUIREMENTS : 
Northern red-backed voles inhabit areas that contain dense ground cover
for protection from weather and predation [19,21].  On the Kenai
National Wildlife Refuge in south-central Alaska, the presence of
northern red-backed voles was positively correlated with protective
cover [2].  During the winter, northern red-backed voles use layers of
thick moss or matted vegetation as thermal cover [20,21].  During the
mid-winter months in a spruce forest of central Alaska, all northern
red-backed voles on a control area aggregated in a small area of thick
moss cover, despite abundant food resources elsewhere on the trapping
grid [21].


FOOD HABITS : 
Northern red-backed voles eat the leaves, buds, twigs and berries of
numerous shrubs; they also eat forbs, fungi, mosses, lichens, and
occasionally insects [1,2,21].  Berries are generally the major food
item in the diet of northern red-backed voles and are eaten whenever
available.  In central Alaska, West [21] found that northern red-backed
voles relied heavily upon the fruits of several berry-producing plants
during all seasons.  These included bog blueberry (Vaccinium
uliginosum), mountain cranberry, black crowberry (Empetrum nigrum),
comandra (Comandra livida), and bunchberry.  Northern red-backed voles
primarily ate berries during the fall and winter.  Lichens were consumed
only during the winter and spring.  In early summer, when berries are
not available, mosses (unspecified spp.) were eaten.  The mid- to late
summer diet of northern red-backed voles also included a large
proportion of mosses, although berries were still the primary food [21].

Northern red-backed voles on the Kenai National Wildlife Refuge fed
during the summer on berries of species such as mountain cranberry and
bunchberry.  They also ate fungi, succulent green plants, and insects.
As fungi became plentiful late in the summer, they made up a large
percentage of the diet.  Mountain cranberry consumption declined as the
summer progressed even though berry abundance increased.  This suggests
that fungi were preferred over mountain cranberries.  The amount of
truffle in the diet remained constant throughout the summer [2].


PREDATORS : 
Some predators of northern red-backed voles include American marten
(Martes americana), Arctic fox (Alopex lagopus), red fox (Vulpes
vulpes), short-tail weasel (Mustela erminea), coyote (Canis latrans)
[15,19,24], and probably most other predators of small mammals that
occur within the range of northern red-backed voles.  In Alaska,
northern red-backed voles and voles (Microtus spp.) comprised 74 percent
of the diet of American martens in the summer and 68 percent of the diet
during the winter [24].


MANAGEMENT CONSIDERATIONS : 
Small mammals are the primary means by which hypogeous fungal spores are
dispersed.  The extensive use of hypogeous fungi, such as truffle, by
northern red-backed voles promotes the establishment of symbiosis
between mycorrhizal fungi and higher plants in disturbed forest areas on
the Kenai Peninsula of Alaska [2].


REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Clethrionomys rutilus | Northern Red-Backed Vole