Latest Census Shows Decline
in Alaska's Largest Caribou Herd
May 19, 2008
Kotzebue, Alaska - The Alaska Department of Fish and Game (ADF&G)
has released its population estimate of the state's largest caribou
herd. The photo-census of the Western Arctic Caribou Herd, conducted
in July 2007, yielded a new population estimate of 377,000 caribou
a decline of 113,000 animals since the last count in 2003.
ADF&G caribou biologist Jim Dau is carefully weighing the
significance of the census for this highly valued herd, which
currently ranges from the North Slope to eastern Norton Sound,
and the Chukchi Sea to the Koyukuk River."
Dau is confident about the
accuracy of the estimate. "We radio tracked collared caribou
extensively from July through mid May and determined that almost
the entire herd (99%) was present during the photography,"
he said. "Photo quality was generally good, and we hired
the most experienced caribou counter in the state to count the
photographs. Also, the estimate is consistent with annual estimates
of adult mortality and calf survival."
Alaska Reindeer [between
ca. 1900 and ca. 1930]
This historical photograph forms part of: Frank and Frances Carpenter
collection (Library of Congress). Gift; Mrs. W. Chapin Huntington;
Courtesy Library of Congress Prints and Photographs Division
The Western Arctic Herd numbered 242,000 caribou in 1970, and
then plummeted to 75,000 by 1976. The herd steadily grew until
possibly peaking at 490,000 animals around 2003. The loss of
113,000 animals from a herd of nearly half a million caribou
in four years doesn't entirely surprise or alarm
caribou biologists, but they are definitely taking notice.
Dau, who has monitored the Western Arctic Herd since 1988, is
still not sure whether the decline is the beginning of a downward
trend, or the result of several recent mid-winter thaw-freeze
events. "With the herd so high for so long, we've been waiting
for the shoe to drop, but we may not necessarily be there yet,"
In December 2005, temperatures rose above freezing and rain soaked
the snow cover for two days. "When cold temperatures returned,
the herd's winter range was encased in a thick layer of near
impenetrable ice, and caribou died in droves," said Dau.
A similar warming event in January 2007 brought four days of
rain, and Dau anticipated another large die-off. Instead, the
prolonged warming period, coupled with high winds, eliminated
the snow cover and dried the surface vegetation. No subsequent
ice crust formed and the availability of critical winter lichens
actually improved. "It's a fine line whether these thaw-freeze
events are good or bad for caribou," Dau explained. "Weather
both summer and winter has been a wild card in recent
years, and it's playing Russian roulette with the caribou."
A twenty-five year study conducted by Federal Bureau of Land
Management biologists has documented a decreasing amount of lichens
in the herd's winter range on the eastern Seward Peninsula and
Nulato Hills. Dau is not sure if this is impacting the herd yet,
noting, "Caribou health is the ultimate expression of range
quality and, in recent years, caribou have gotten very fat during
summer and maintained good body condition throughout winter when
weather was not unusually severe." He added, "In 2007
adult cow mortality was low and calf survival was high, which
suggests the herd may still be capable of stability or even slow
In the fall of 2007, ADF&G veterinarian Dr. Kimberlee Beckmen
collected tissue and organ samples from the herd to test for
disease and assess body condition. She gave the herd high marks
for overall health. Dau said local subsistence hunters agree
that caribou have seemed healthy and fat.
Despite the reduction in numbers, the herd is clearly still very
large. By comparison, the Porcupine Herd is the state's second
largest herd and numbers 123,000. Nonetheless, Dau said this
latest count signals the need for caution regarding the herd's
range. "It's certainly not lost on us that other large caribou
herds in Alaska and Canada are now declining as well. Taken collectively,
these declines may merely be a coincidence," he said. "Alternatively,
we may be entering a phase when conditions throughout North America
are less favorable for caribou than during the past 30 years."
The next Western Arctic Caribou Herd census is scheduled for
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