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TomBrooklyn
09-05-2003, 09:44 AM
New York Times

"The Real World, Yellowstone": Wolves on View All the Time

By JIM ROBBINS


YELLOWSTONE NATIONAL PARK, Wyo. - For decades wolf biologists have had to
make do with furtive and fleeting glimpses of the wild behavior of the
animal they study, usually in remote and harsh corners of the world.

But now they can watch packs of wolves here go about the full range of their
lives, from hunting to raising pups to courtship rituals and sex. The
observations are beginning to create a much more complex portrait of wolves.

"It's the best wolf laboratory ever," said Dr. L. David Mech, a senior
research scientist with the United States Geological Survey in St. Paul and
a leading expert on wolves.

Several factors came together to create the unparalleled view. One is
volume. In early 1995, 14 gray wolves were released into the prey-rich park,
and the next year 52 more here and in central Idaho. Nine years later their
number in the park has grown to 14 packs, or 148 animals, not including 14
new pups this year. Experts say it is the highest density of wolves in the
world.

Topography also plays a part. There are wolf packs in Alaska and northern
Minnesota and Wisconsin, but the terrain is either remote and access to it
difficult, or it is heavily forested. Here it is hilly but treeless and
open, and the wolves are easily visible, allowing biologists to watch
without getting too close. They don't even have to leave their car if they
choose.

It may also be that the animals are oblivious. "They were held in pens and
got used to the sights, sounds and smells of people," Dr. Mech said. "They
may have realized they didn't have to be afraid," a trait the first
generation may have passed on.

That doesn't diminish their wild behavior, he said. As Daniel Stahler, a
National Park Service wildlife specialist, sat in his white government-issue
S.U.V. recently, with cars and trailers whizzing by, he pointed to a broad
grassy meadow on the side of a mountain. "I've probably seen 25 kills on
that slope," he said. "Their whole life unfolds in front of observers a
couple of miles away. Kill rate, prey selection, interaction with prey and
scavengers. Yellowstone is the first to do this at this level."

In nearly four decades as a researcher before the Yellowstone
reintroduction, Dr. Mech estimated that he saw 100 to 200 wolf-prey
encounters. Dan McNulty, a former student of Dr. Mech who has been
researching wolves for eight years here, has witnessed more than 700.

Technology has also helped expose the lives of the Yellowstone wolves. Many
are fixed with a collar that contains a global positioning receiver. Twice a
day orbiting satellites fix the position of the wolf and those data are
stored in the animal's collar. By tracking a second, separate radio
transmitter, researchers can find the wolf on the ground, get within a
quarter-mile and then download the stored information with a laptop
computer. Once they know where the wolves have been, biologists can hike in
and analyze the kills.

Yellowstone researchers are adding to their knowledge of how wolves live so
quickly that they have been able to tabulate only a small part of the raw
data. One major new finding involves the way packs of the highly territorial
animals interact in encounters with other wolves and packs, something rarely
observed before.

"We can see ritualized behavior with wolves meeting for the first time or a
wolf coming into a new territory," Mr. Stahler said. "When a dispersing male
enters a neighboring wolf pack's territory, ritual behavior is a big part of
that. Avoiding eye contact, and the ear and tail position are critical. The
wrong behavioral move and he could get killed."

Researchers have also documented something previously unknown about pack
dynamics - a long-distance romance. A young male from the Chief Joseph pack
loped to the territory of the Druid pack a few miles away, and mated with
two young females, offspring of the pack's alpha male. The older male either
couldn't - or didn't want to - stop the amorous activity.

"The old man is related to his daughters," and wolves generally avoid
inbreeding, Mr. Stahler said. By allowing the interloper to mate with his
offspring, he said, the old male "is benefiting from them passing on their
genes." This liaison, and possibly others like it, may be due to the fact
that the park is saturated with wolves and the male can't establish a new
pack.

There has been another rare mating event. A female in a pack commonly breeds
and whelps an average of five pups. In 2001 three litters were born to the
Druid pack, for a total of 21 wolves.

New details have also emerged on how wolves kill. "There are just two or
three good hunters in the pack," Mr. Stahler said. The rest, he said, the
young and the old, "are just baggage." Those three wolves will harass a
bison or an elk, taking great care to avoid antlers or horns, which can mean
death. They charge and parry as they wait for the animal to tire, and drop
its defenses. When the opening is presented, two wolves typically charge the
rear and clamp their powerful jaws on the hind legs, while the third will
seize the throat in a crushing bite. As the animal frenetically snorts and
stamps, trying shake off the wolves, they try to hang on until the animal
suffocates or bleeds to death.

But dropping an 800-pound elk is extraordinarily difficult, even for animals
born to it. Elk are smaller and easier to kill than bison - one in four
attempts on elk results in a kill, while they manage to kill just 1 bison in
25 attempts.

The remote Pelican Valley of the park has provided researchers with a
remarkable glimpse of the predator-prey relationship between wolves and
bison. Superheated water surfaces here and the ground is dotted with
simmering hot pools and bubbling geysers that give off billowing clouds of
steam. A small herd of bison moves through the steamy valley to feed on the
grass that grows on the warm ground.

Wolves have noticed, and patiently watch for hours until the animals make
the fatal mistake of leaving the bare ground, where they have the strategic
advantage. "Bison are very agile and defend themselves in a group," Mr.
McNulty said. "But when they move through snow they are forced to go single
file and can't fight cooperatively. They get bogged down in the snow."

That is the moment the wolves wait for. One encounter began in the
half-light of daybreak, as wolves initiated their assault on a shaggy,
snowbound bull. "He hooked one wolf and threw it up in the air, and kicked
another," Mr. McNulty said. The drama continued all day and into darkness,
which shielded the victor from view - for a while. "The next morning wolves
were seen on the carcass," he said. But one of the attackers was mortally
injured by the bison.

Hunting is risky for wolves. Biologists have documented eight wolves killed
by prey in the park. And if hunting does not kill them, it can cause serious
injuries. "The only weapons wolves have is four canines," Mr. McNulty.
"Imagine trying to kill a bison with your teeth. You are exposed during that
attack."

All the more frustrating, then, is being chased off the kill. Two days later
a grizzly bear poached the bison carcass in the Pelican. Wolves are no match
for a grizzly, which swatted them away. The bear ate its fill and slept on
the carcass.

With six large predators, including wolves, roaming its prey-rich plains,
Yellowstone is unlike anywhere else in the Lower 48, Mr. McNulty said,
providing a glimpse not only into an unusual ecosystem, but also into an era
that seems gone forever. "We're seeing the same system early frontier
naturalists saw on the prairie," Mr. McNulty said. "After they left, the
prairies were overrun with Europeans and wildlife was extinguished."

For Dr. Mech, who has chased wolves to study them from Minnesota to the
Arctic for 45 years, the epiphany came when he watched seven minutes of a
movie taken in Yellowstone by Bob Landis, the filmmaker.

It was always assumed, he said, that wolves killed the old, sick and the
weak because those animals fell behind in the chase. Not true, he said.
Wolves look for these animals from the outset. "They scan the herd and
minimize the possibility of damage to themselves," he said. "For me that's
the outstanding event."