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Bears Preying on Musk
Oxen in Arctic Refuge
Associated Press
Posted September 29, 2003
Musk ox kills by brown bears in the Arctic National Wildlife
Refuge have dramatically increased over the past decade,
according to studies by federal and state biologists.
A number of individual Arctic grizzlies have learned how
to stalk and take down the shaggy animals, said ANWR ecologist
Patricia Reynolds, with the U.S. Fish and Wildlife Service.
"I think the reason that bears are efficient predators
is because they are adaptable, and they have the ability
to switch to whatever is out there," Reynolds said.
In at least 10 instances, the bears killed two to seven
musk oxen at once, possible examples of a relatively rare
phenomenon biologists call "surplus killing,"
where a predator kills more prey than can be consumed immediately.
"This really surprised us," Reynolds told scientists
at an Arctic science conference in Fairbanks last week,
where she presented a paper called, in part, "A Search
for Weapons of Muskox Destruction."
In an article published last year in the journal Ursus,
Reynolds and two co-authors reported that 28 of 46 known
musk ox deaths took place during multiple kills, with most
occurring since 1999.
Bears don't usually engage in such surplus killing and
musk oxen can be exceedingly dangerous prey, able to gore
attacking bears with thrusts from their powerful heads and
their sharp horns. At least one bear is thought to have
died as a result of battling musk oxen on the tundra, and
others have been wounded.
"It's a risk to them, and that's the interesting trade-off,"
Reynolds told the Anchorage Daily News.
The rise in bear predation comes as ANWR musk oxen have
crashed in number, from a high of 386 in 1986 and an average
of about 325 in the early 1990s to an estimated 50 this
year.
Where bear kills once accounted for virtually no musk ox
deaths, predation took an estimated 13 percent of the ANWR
herd in 2003.
Reynolds, who has studied refuge musk oxen for more than
20 years, said the overall decline in ANWR has been driven
mostly by tough winter conditions, not bear predation.
Crusty or deep snow has been forcing the animals to work
harder to find food. Possibly as a result, ANWR musk oxen
haven't been producing many calves.
Overall, Alaska's musk ox population appears to be healthy,
with 450 in the Arctic region and an estimated 5,000 in
the state.
Hunted to extinction in Alaska in the 1800s, musk oxen
were reintroduced into the state in the 1930s and into ANWR
in 1969.
Associated Press
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