BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Rangifer tarandus | Caribou 



TIMING OF MAJOR LIFE HISTORY EVENTS : 
Mating Season - mid to late October
Gestation - 7.5 months
Birthing Season - May and June; females within a herd often calve 
                  within 10 days of each other; twinning rare; 
                  calf mortality high
Age of Maturity - 3.5 years for females; young males may
                  not breed due to competition from other males
Antlers - occur in both sexes; some females in certain populations
          do not have antlers; females shed about calving time; males
          shed during or after the rut
[5,24,29]


PREFERRED HABITAT : 
Woodland caribou inhabit high alpine meadows and open subalpine forests,
as well as lower elevation forests.  During summer they seek dense
forests where temperatures are cooler and vegetation is succulent.  In
winter caribou move to more open forests to feed on arboreal lichens,
moving to higher elevation, south slopes in late winter [24,29].  In the
Selkirk Mountains of Idaho woodland caribou move to low elevation
cutover units in spring to take advantage of early green-up [32].
Caribou can smell food under deep snow (24 inches [60 cm] or deeper) and
dig craters in the snow to access food [23,24].  Barren-ground caribou
prefer the open tundra, but some populations seek tree cover in adjacent
boreal forests during winter [19,24].  Irregular terrain is preferred
over uniform terrain because the variable snow depth makes food more
accessible in winter [5].  Both barren-ground and woodland caribou use
poorly drained meadows, sedge bogs, and moss muskegs [24].


COVER REQUIREMENTS : 
Caribou require escape cover from predators during calving; predation is
a primary population-limiting factor.  Woodland caribou need the cover
of dense forests with a large supply of arboreal and ground lichens, as
well as herbaceous forage.  Caribou are not easily frightened by man's
activities, and therefore need large spaces to roam where hunting and
poaching pressures are minimized.  Caribou also need protection against
flying insects in summer.  Cool, shady forests, windy hilltops, or
snowfields can provide an escape [5].


FOOD HABITS : 
Studies in the last 20 years have concluded that caribou are not as
entirely dependent on lichens for food as was once thought [16,18,19].
Bergerud [4] stated that caribou do not have specialized feeding habits
and can use most plants when necessary.  Lichens are more important
locally, especially to caribou populations that depend on arboreal
lichens during winter [32].  Scotter [30] listed the following lichen
families as important food sources:  Caliceaceae, Cypheliaceae,
Peltigeraceae, Gyalectaceae, Lecideaceae, Cladoniaceae, Umbilicariaceae,
Lecanoraceae, Parmeliaceae, Usneaceae, Calophlacaceae, Teloschistaceae,
Buelliaceae, and Physciaceae.  Important lichen genera are Cladonia,
Cladina, Cetraria, Peltigera, Stereocaulon, Usnia, and Alectoria
[23,25].  Caribou also eat grasses, sedges, and twigs and leaves of
woody plants [24].  Other foods include horsetail (Equisetum spp.),
willow, huckleberry and blueberry (Vaccinium spp.), larch (Larix spp.)
needles, alder (Alnus spp.) leaves, bog birch (Betula glandulosa),
cottongrass (Eriophorum spp.), sweetgale (Myrica gale), Labrador tea
(Ledum groenlandicus), bearberry (Arctostaphylos uva-ursi), and black
crowberry (Empetrum nigrum) [2,5,8,23,29].


PREDATORS : 
Caribou predators include man, wolves (Canis lupus), grizzly bears
(Ursus arctos), lynx (Felis lynx), and eagles (no species given) [24].


MANAGEMENT CONSIDERATIONS : 
Caribou populations fluctuate with greater intensity than any other
North American ungulate; habitat factors and predation are largely
responsible [7].  Predation, severe weather, and social interactions
cause high calf mortality.  Caribou are also susceptible to overhunting
and poaching because they are approachable [5].  Man-made barriers, like
dams and pipelines, disrupt migration of some herds.  Caribou suffer
from a variety of fungal and bacterial diseases, as well as parasites;
especially the meningeal worm, Parelaphostrongylus tenuis, carried by
the white-tailed deer [22,24].  Zack [35] listed habitat management
guidelines for caribou seasonal cover.  Johnson and others [14] made
recommendations for logging and road building in woodland caribou
habitat.


REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Rangifer tarandus | Caribou