Updated June 30, 2007
A
mountain lion paid the ultimate price for his gluttony after
helping himself to too many servings of lamb and venison near
southwestern Arizona’s Kofa National Wildlife Refuge. Earlier
this month wildlife officials killed the lion as it guarded the
fresh carcasses of two desert bighorn sheep and a mule deer. The
lion threatened recovery of a faltering sheep species in the
refuge. But even as the Arizona Game and Fish Department dispatched
wildlife officers to destroy the offending puma, the department
offered hunters 12 licenses to kill desert bighorn sheep in the
protected wildlife area. Although predation threatens the
vulnerable sheep herd, paradoxically, targeted hunting of rams may
actually help save the desert bighorn sheep from extinction.
“This is not about hunting lions,” or sheep,
says Gary Hovatter, an information and education program manager
for the Arizona Game and Fish Department. “It’s about
restoring bighorn sheep herds.”
Established in 1939,
the Kofa National Wildlife Refuge encompasses more than 600,000
acres and serves as one of the few remaining habitats for desert
bighorn sheep. The rugged Kofa and Castle Dome Mountains rise
steeply from the scrublands that epitomize this desert habitat. In
the refuge, desert bighorn sheep share their home with desert
tortoise, desert kit fox and now desert mountain lions.
Bighorn sheep numbers in Kofa have dropped in the past few
years from more than 800 individuals in 2000 to around 390 by last
year. Ecologists attribute sheep declines primarily to cycles of
drought, with sheep recovering during years with greater rainfall.
But recently, the number of sheep has dropped in spite of more
rain, and biologists blame mountain lions.
At least five
mountain lions now live in the refuge, according to recent surveys,
including one lion with cubs. “The single biggest change in
the Kofa was the establishment of a resident lion
population,” says Hovatter. “For almost a hundred
years, there’s been no history of a mountain lion population
here.”
Mountain lions kill one large game animal a
week on average, and with at least five lions residing in Kofa,
wildlife managers worry that the cats could over-hunt vulnerable
game populations like the desert bighorn sheep.
The young
male lion killed last week was an overzealous hunter, says Bob
Henry, a biologist with the Arizona Game and Fish Department.
“We had five documented kills in three months, period,”
he says, referring to the three animals the lion hoarded and two
others from another kill site.
In the most recent attacks,
Hovatter thinks the lion was staking out a watering hole in the
refuge, “killing every big game animal that came to the
water.”
And game and fish officials worry about the
potential for more losses. Four of the five animals killed by the
lion were bighorn, including three ewes, a significant loss,
especially when considered in a larger context: Since bighorn
populations increase at the annual rate of 17 yearlings per 100
ewes, Hovatter says, “this lion’s kills accounted for the annual
recruitment we would expect to get from 25 ewes.”
Now
biologists plan to backtrack the puma’s whereabouts using
previously recorded satellite data, so they can search for other
animals killed by the lion.
While some decry killing
mountain lions in a wildlife refuge, game and fish officials
explain that destroying the animal is a better choice than
relocating it. Capturing and moving lions stress them, and once
placed in a new habitat they fight with, and are often killed by,
other lions. Sometimes they starve to death.
Paul
Krausman, a professor of wildlife conservation and management at
the University of Arizona in Tucson, calls the behavior of this
cougar atypical. “I’ve never seen a situation where you
have three big fresh kills at once, especially with a young male
lion,” says Krausman. “But,” he concedes,
“it is possible.”
Even so, Krausman
continues, “I don’t think those five lions would
devastate the sheep population. If they do, then there’s
something else wrong with [the sheep].”
In fact,
the struggling herd contends with other challenges made worse by a
cougar killing ewes. The herd currently has an imbalance of rams to
ewes, creating a situation similar to a small town where men
outnumber women. When a bunch of men hound the one woman in the
bar, tensions may erupt in an all out brawl, leaving everyone
exhausted. In Kofa, a few dominant rams guard as many ewes as they
can; the remaining rams roam the edges of those groups, hoping to
gain access to the females. So hunting rams can actually relieve
some of the stress on the bighorn sheep ewes.
Hunting has
other benefits for conservation, says Hovatter. Money from licenses
funds conservation projects, protecting habitat for many species.
And hunting groups sometimes volunteer time to assist ecologists
with fieldwork.
Wildlife managers hope their seemingly
paradoxical strategy will boost sheep numbers high enough in Kofa
that they can then reintroduce them in other areas.
“The Kofa is some of the most rugged country in the
United States,” says Krausman, “It’s amazing to
go out there and see bighorn sheep surviving.”
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