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seasons for descriptions
Pregnant cows
destined for the calving
grounds initiate spring
migration. It corresponds with
significant snow melt — commonly in April and May. Bulls, yearlingsand
dry cows follow weeks later. Pregnant cows (who move north before the
flush of early spring forage) are in constant energy deficit during this
period, traveling an average of 20km per day. Deep snow, early breakup,
and spring floods are
just some of the factors that
can delay this tough stage
of the Porcupine Caribou
Herd’s annual journey.
Insects usually
dictate when this dramatic
stage of the caribou’s annual migration begins. Spurred on by biting
mosquitoes and oestrid flies, tens of thousands of caribou group together
and move like a river across the landscape, covering as much as 25km/day
as they search out areas that offer relief from the bugs
(i.e. windy ridgetops) and
good quality food.
Porcupine caribou
calve almost always between
June 1 and 10. Adult females are
in the poorest condition of the year
when they arrive on the calving grounds and, after giving birth, are
dependent on
the area’s high-energy food. The general absence of wolves and
insects are just some of the characteristics that make
this area worthy of a 2-month-long
1,000km migration. Even with this sanctuary, life is difficult. An
average of 25% of the calves
get killed in their first
month of life.
Towards the end
of July and the first half
of August, the large aggregations
of caribou split into smaller bands
that disperse throughout northeastern Alaska and the Yukon. Where exactly they go is largely determined by food quality and the presence of insects. Areas that offer good forage and cool humid conditions are sought, such as northeastern Yukon’s Richardson Mountains. Lactation demands
are still high for the nursing
cows and insect harassment
can easily send them
into energy deficit.
of July and the first half
of August, the large aggregations
of caribou split into smaller bands
that disperse throughout northeastern Alaska and the Yukon. Where exactly they go is largely determined by food quality and the presence of insects. Areas that offer good forage and cool humid conditions are sought, such as northeastern Yukon’s Richardson Mountains. Lactation demands
are still high for the nursing
cows and insect harassment
can easily send them
into energy deficit.
The start, pace,
and progress of the fall
migration are all strongly
influenced by weather. The caribou
tend to move slowly southwards
in a widely dispersed pattern
until substantial snowfall or a rapid
temperature drop move them south
more quickly. However if the weather
improves (i.e. temperatures rise), the migration may slow down, halt, or even reverse temporarily until renewed snowfalls and cold temperatures send the
caribou south again.
and progress of the fall
migration are all strongly
influenced by weather. The caribou
tend to move slowly southwards
in a widely dispersed pattern
until substantial snowfall or a rapid
temperature drop move them south
more quickly. However if the weather
improves (i.e. temperatures rise), the migration may slow down, halt, or even reverse temporarily until renewed snowfalls and cold temperatures send the
caribou south again.
The rut is a spectacular
phase of the caribou’s
annual life cycle, a period when
the big bulls spar with one another
for the privilege of mating with the
cows. Dueling and chasing preoccupy
the bulls to the point of exhaustion,
rendering them easy prey for wolves
and bears that continue to shadow the
migration. There is no affinity for
where the rut occurs. Rather, it
transpires wherever the herd
happens to be along
the fall migration.
This is the time of
dark and cold when Arctic
temperatures can plummet as
low as –50C. Surprisingly, if snow
isn’t too deep, it is also a time of year
when the well-adapted caribou can gain
weight. The cows are no longer lactating,
the bulls aren’t sparring, and the herd,
although widely scattered, isn’t moving
much compared to the rest of the year.
Winter range is generally south of the
treeline, where the snow remains soft,
making it easy for the caribou to
paw and “crater” down to
the ground lichens that
sustain them.
April 8, 2003:
Karsten Heuer + Leanne Allison
left the remote community of
Old Crow,Yukon, to join the Porcupine
Caribou Herd on their epic life journey. For 5 months the Canadians migrated on foot with the 123,000-member herd from wintering to calving grounds in Alaska's Arctic National Wildlife Refuge, and back again — 1500km across snow and tundra. They completed their journey on Sept. 8, 2003 and headed straight to Washington, DC to tell politicians + activists what they found.
Karsten Heuer + Leanne Allison
left the remote community of
Old Crow,Yukon, to join the Porcupine
Caribou Herd on their epic life journey. For 5 months the Canadians migrated on foot with the 123,000-member herd from wintering to calving grounds in Alaska's Arctic National Wildlife Refuge, and back again — 1500km across snow and tundra. They completed their journey on Sept. 8, 2003 and headed straight to Washington, DC to tell politicians + activists what they found.
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