Caribou on the Move
“There are two forms of nature. One is the nature you
see every day. The other aspect of nature is something very
distant, very remote. You don’t see it, but you know it’s
there. It’s spiritual. It has to do with imagination, with
soul. Without this kind of nature our daily life may not change,
but something—soul—is missing.”
~Michio Hashimo, caribou watcher
Although they’re not the least bit aware of it, caribou have
become the subject of a hot political debate that has been
boiling over the past five years. It would seem these unobtrusive
creatures of the remote arctic tundra and boreal forests of
North America and Greenland would be far from the spotlight
of national politics, but their future became uncertain when
Washington announced plans to open the Alaska National Wilderness
Reserve (ANWR) to oil and gas drilling. At almost twenty million
acres, ANWR would seem big enough a place to accommodate the
interests of bipeds and quadrupeds alike, but the narrow coastal
plains, where fossil fuels are suspected to abound, happens
to also be the center of biological activity for a quarter
of the year. This valuable two thousand acre stretch is the
calving grounds for two large caribou herds.
Caribou are creatures on the move. Weather patterns and
biological instinct trigger migratory movement. Each spring
the pregnant cows lead the herd from their southern winter
range to their northern calving grounds between the Katakturuk
and Kongakut Rivers. Having left before the flush of early
spring foliage, the cows suffer a constant energy deficit
on this trail. They travel twelve to fifteen miles a day,
crossing icy rivers and plodding through spongy muskeg to
reach their destination by late-May, early-June. Here they
give birth in relative safety; the wolves, grizzlies and eagles
that would prey on newborn calves tend to stay below in the
woodland forest areas. Although calves can run within ninety
minutes of birth, they and their depleted mothers are no matches
against a persistent predator. The high-quality grasses, sedges,
flowering plants, willow leaves, and mushrooms of the calving
grounds soon restore the health of the cows. The reddish-brown
calves, which weigh approximately thirteen pounds at birth,
grow stronger and stronger, doubling their weight within ten
to fifteen days. Yet even in this sanctuary, 20-25% of caribou
calves die in their first month of life.
By mid-summer, mosquitoes and warble flies are almost intolerable,
driving the herd in thousands to find refuge in old snow patches
or windy ridge tops. By staying in these huge post-calving
aggregations, the herd continues to protect the cows and calves
from predators. As August approaches the herd will disperse
into smaller groups to feed. Where the caribou goes largely
depends on food-quality and the presence of insects. In September
they drift toward their winter range, which shifts slightly
from year-to-year, minimizing the effects of over-grazing.
Mating occurs en route in September and October. Caribou,
which are members of the deer family, are the only species
in which both females and males grow distinctive antlers.
These antlers can grow up to four feet in width. As fall approaches,
the larger bulls, weighing between 350-400 pounds, begin to
shed the fur on their antlers, called velvet, marking the
approach of the breeding season. Sparring, dueling, and chasing
each other, bulls compete for breeding rights. Unlike other
herding species, bulls do not maintain harems, but instead
fight for control within a space. Stronger bulls win space
and cows toward the center of the herd, where predators are
kept at a minimum. Weaker and younger bulls are forced to
the dangerous outskirts. Females can mate as young as sixteen
months, although most will not until they are at least a year
older than that.
And yet the move to winter quarters continues. As the weather
turns cold, caribou adapt. Their metabolic rate lowers, enabling
them to reduce food intake. Throughout the winter they use
their concave hooves to dig in the snow to feed on lichens.
These broad hooves are also ideal for tramping across soft
ground and paddling in rivers. Caribou's unique hairs trap
air, providing insulation and buoyancy. An inner compass pushes
them onward. Nothing it seems can halt the annual migration.
Yet the one thing which has noticeably interrupted their fixed
patterns has been the human influence on their habitat.
22,000 caribou are killed each year, providing food, shelter,
and medicine for hunters and arctic tribes, such as the Gwitchin.
In Alaska, hunters harvest more caribou than any other big
game species. Maintaining a healthy caribou herd contributes
to the economy in Alaska. These activities have never threatened
the caribou, which now number 950,000 in Alaska. Aboriginal
hunters have been a part of the caribou story for thousands
of years. It is not man himself that is the threat, as the
caribou’s domesticated Eurasian cousin, the reindeer, can
attest. It is the modern activities of man: logging, coal
mining, and oil and gas exploration which affect the caribou
most dramatically. Surveys of oil and gas facilities in Prudhoe
Bay show that caribou will not calve within thirty miles of
such man-made structures. Unfortunately, the strip of land
now being targeted for exploration is only thirty miles wide.
Unlike the situation at Prudhoe Bay, there is no good alternative
calving grounds. And so, time will only tell how these Ice
Age survivors will weather their next storm.
About the Author
Emma Snow has always adored wild animals. Emma provides content
for Wildlife Animals http://www.wildlife-animals.com
and Riding Stable http://www.riding-stable.com.