General
information on Quebec Labrador George River Caribou
Caribou or Tuttu as the native Inuktitut
call them and the innu called them Mushuauattik
has a weight for the males or (stags or bulls )of 225 pounds
to 350 pounds while the female or (does) have a weight
of 100 pounds to 250 pounds. The height to the shoulder of a
stag will vary from 40 " to 98" tall and a
caribou will have a life span in the range of 12 to 15
years.
Natural History: Caribou are the only
deer species in which both males and females have antlers.
Their antlers, which are shed every year, have a long,
sweeping main beam up to five feet wide. Each side has one
or two tines, or branches, and each tine may have several
points. The larger racks of caribou bulls are considered
trophies by big-game hunters.
A single calf is born in the spring. Unlike most deer,
caribou young do not have spots. They are able to walk
within two hours of birth and are weaned gradually over
several months. After calves are born, females with newborns
gather into "nursery bands" and separate from the
rest of the herd. Gradually, the bulls and barren cows
rejoin the calving cows at the calving grounds. These larger
groups of caribou offer some protection for the calves from
predators such as wolves, bears and lynx.
Caribou feed on sedges, grasses, fungi, lichens, mosses,
and the leaves and twigs of woody plants such as willows and
birches. Although some herds stay on the cold tundra all
year, most caribou have distinct summer and winter ranges.
The large northern herds migrate over long distances,
frequently crossing large, swift-running streams and rivers.
Consequently, even caribou young are extremely strong
swimmers.
Caribou Hair
Their fur allows the caribou to survive in an extremely
cold climate. To understand the insulating property of the
fur, let's take a look at the individual hair.
Each club-shaped hair contains countless cells holding
air, and is surrounded by many, many other hairs. These
hairs are thinner and softer, and they, in turn, hold a lot
of air. All this means that each caribou is surrounded by a
cushion of air and compact hairs, allowing the animal to
feel at ease at temperatures below -40° Celsius.
As a bonus, this insulating layer also offers very good
flotation. This helps the caribou get across the thousands
of lakes and rivers it must negotiate during its annual
migration. Because they float so well, the caribou spend
less energy swimming!
Caribou Feet
Caribou have special adaptations that allow them to
survive their harsh arctic environment. Long legs and broad,
flat hooves help them walk on snow and on soft ground such
as a peat bog. A dense woolly undercoat overlain by stiff,
hollow guard hairs keeps them warm. Caribou dig for food
using their large, sharp hooves.
The caribou have developed a spectacularly efficient way
to counter the effects of cold: blood temperature in their
feet can vary, allowing them to lose less heat during cold
weather. The heat that would normally follow the blood into
the feet is redirected instead to the body. Meanwhile, the
biological thermostat in the feet gets turned down, allowing
their temperature to drop close to the freezing point -
without causing any discomfort. Humans don't have this
advantage. We get cold feet when the temperature drops. Our
northern migratory friends cross steep mountain ranges,
rivers whose ice is breaking up, huge and windy lakes, and
icy and inhospitable stretches of land.
All this in order to constantly remain in a group, where
protection is best assured.
To adapt to all this physically demanding travel, the
caribou have developed a highly perfected circulatory
system. A caribou can travel 40 kilometers per hour
for over an hour, or swim dozens of kilometers, without
feeling put out in the least. The solid hooves of the
caribou are ideally suited for the punishment they take on
land (caribou are the world's most migratory land mammals,
traveling many thousands of kilometers per year). But they
also act as powerful paddles. Thanks to their hooves,
caribou can swim at speeds of up to 11 kilometers per hour.
In order to best provide the essential support necessary
for long journeys through forests and mountains, and for
sprints across the Arctic terrain, caribou hooves change
with the seasons. In winter, the bottom of the hoof is
covered with hair, providing insulation and traction. The
hoof itself also lengthens, and its bottom becomes concave -
so that muscles in the toes do not come into contact with
the frozen ground.
The Arctic landscape just wouldn't be the same without
the caribou. Under its fur, this creature of the cold hides
many fascinating adaptations essential to survival in an
unusual environment.
Caribou, or reindeer, are land mammals of the cervidae
family - and therefore cousins of the moose, elk and
white-tailed deer. They live in the Earth's Arctic and
sub-Arctic regions, although some populations extend
southward into coniferous forests and southern mountain
ranges. They are a circumpolar species, found in North
America, Europe and Asia. Caribou distribution patterns vary
widely between one country (or continent) and another.
Caribou are called Rangifer tarandus by
biologists. Generally, caribou refers to members of the
species living in North America, while reindeer refers to
their European and Asian counterparts. The unique
characteristics of caribou set them apart from other members
of the cervidae family - and, more importantly,
assure their survival in a harsh climate
Antlers are one of the most interesting characteristics
of the caribou. Both males and females have antlers, making
the caribou unique among members of the cervidae
family. In other cervidae species, only the males
grow antlers. The fact that caribou have such long legs,
combined with the presence of antlers on females, suggest
that they may be the oldest cervidae still living.
Antlers:
While they grow, the antlers are covered in soft brown
hair, known as velvet. Once the antlers are fully formed,
the blood vessels contract into their base, and blood stops
flowing through them. At this point, the antlers lose their
velvet, giving them a bloody appearance. But this
superficial blood dries quickly, and the antlers turn brown.
Exposure to the sun will fade the antlers; on females, they
become so pale as to be nearly white. The average lifespan
of an adult caribou is eight to ten years. They reach
maturity at about three years. As with most deer species,
male caribou fight each other for a harem of five to 40
cows. This sparring, called rutting, occurs in the fall.
Injuries in this natural quest for dominance are rare,
although occasionally the bulls' antlers lock together and
both animals die.
Caribou antlers can grow to six or seven kilograms on
males, and one kilogram on females. A lot of energy goes
into growing them - and before long they wind up on the
ground.
The antler cycle among male caribou is similar to that of
other northern cervidae. Depending on the age of the
animal, antlers start growing between April and June. The
older males' antlers start growing sooner, so that they can
be ready in time for mating season. Insect bites are a
particular nuisance for caribou. When mosquitoes are
numerous, a caribou may lose up to half a pint of blood a
day. In coastal areas, they seek temporary relief by
submerging themselves in water. They may seek windy
hilltops, dry, rocky slopes, or snowfields if they do not
have access to a coastal area. Barren ground caribou have
been known to stampede in attempts to escape the ravages of
mosquitoes, warble flies or nostril flies.
By early September, the lead males' antlers have lost
their velvet. They are now ready for combat and for acts of
bravado. Younger males will have to wait as late as
mid-October before they are ready to enter the fray.
Most of the time, antlers serve simply to dissuade
smaller rivals. As much as possible, the animals avoid
out-and-out combat; it carries a serious risk of injury, and
involves expending a lot of energy in the critical period
just before the onset of winter. Many males die as a direct
result of battles during the rutting period. Others die
during the winter, indirect victims of an overly exhausting
mating season. This explains why most caribou herds have two
females for every male.
Males lose their antlers after rutting, sometime between
November and March. The older members of the herd lose their
now-useless antlers first.
The female antler growth cycle runs on a delayed schedule
compared to that of the males. According to natural
selection, adaptations persist when they offer an
evolutionary advantage. Female caribou antlers provide an
excellent example.
Female Antlers:
There are fewer variations in the female antler growth
cycle than in that of males. The age of individual females
has little influence on the growth cycle; instead, it is
mainly determined by reproductive status.
Antlers start growing in June, with velvet falling off in
October. Those females who will be carrying a fetus during
the winter keep their antlers until a few days after the
birth of their fawn, in June. The antlers help the mother
defend her fawn against predators during the time when it is
most vulnerable.
On the other hand, females not bearing fawns lose their
antlers three or four weeks earlier, in May.
So whether or not they are carrying young, females hang
onto their antlers throughout the winter - long after the
male leaders have lost theirs. The females don't let this
advantage go to waste. They use their antlers to threaten
males into giving up their best sources of food for their
own benefit, and that of their fawns or fetuses. Sometimes,
a male who has dug through two metres of snow to get at a
source of lichen will give way following a threat from a
smaller, antlered female. Males don't usually play a role in
care of the young - but in this instance, without knowing
it, they do contribute to raising the family.
Caribou were once essential to the survival and
livelihood of native peoples of the Arctic. Natives used
caribou meat, milk and organs for food. Hides provided
material for clothing and shelter, and bones, antlers, and
sinews were used to make tools, tableware, and handicrafts.
However, though caribou remain a subsistence food resource,
other uses have declined as native populations have become
more technologically advanced.
