When I first moved to Pescadero, I volunteered as a docent at Año Nuevo State Park. It's an amazing place, home to bobcats, mountain lions, coyotes,
foxes, raccoons, skunks, weasels, brush rabbits
and black-tailed deer as well as the Northern elephant seals for which the Park is best known.
Hundreds of thousands of northern elephant seals
once inhabited the Pacific Ocean. They were slaughtered
wholesale in the 1800s for the oil that could be
rendered from their blubber. By 1892, only 50 to
100 individuals were left. The only remaining colony
was on the Guadalupe Island off the coast of Baja
California.
In 1922, the Mexican government gave protected
status to elephant seals, and the U. S. government
followed suit a few years later when the seals
began to appear in Southern California waters. Since that time, elephant seals have continued
to multiply exponentially, and they have extended
their breeding range as far north as Point Reyes.
Today, there are approximately 160,000 northern
elephant seals.
Grizzly bears and other large mammals were once
common at Año Nuevo, and grizzlies in particular
were a dominant factor in the animal life of the southcoast
region. They were a constant threat to the Ohlones
who lived here for centuries, and they were still
a significant danger for Spanish and early American
settlers during the 18th and 19th centuries. It was not until about the mid-1880s that the
last grizzly in the Santa Cruz Mountains was killed. Unlike the elephant seals, there's no bringing them back here.
That's why it is so incredible to actually see grizzly bears in the wild as we did earlier this fall during our vacation in Yellowstone, Glacier and the Tetons national parks. They are breathtaking. As the following article by Cory Hatch explains, not even a year after the U.S. Fish and Wildlife Service removed protection for Yellowstone grizzlies under the Endangered Species Act, scientists are concerned about the deaths of female grizzly bears.
Less than a year after the U.S. Fish and Wildlife Service removed
protection for Greater Yellowstone grizzlies under the Endangered
Species Act, federal scientists say female grizzly mortalities are
approaching the threshold that could trigger a review.
So
far in 2007, research teams documented a near-record 50 females with
cubs of the year, with an average litter size of 2.16 cubs.
But,
those same researchers estimate that about 18 female grizzlies over 2
years of age have died from hunting accidents, management removals and
natural causes.
Though the overall grizzly bear population is
thriving with an estimated 571 animals, Interagency Grizzly Bear Study
Team leader Chuck Schwartz said the female mortalities are approaching
the sustainable limit of 9 percent.
If female mortality exceeds
9 percent of the population for two consecutive years, bear management
officials from Idaho, Wyoming, Montana, Grand Teton National Park,
Yellowstone National Park and the U.S. Fish and Wildlife Service must
hold a management review that could put grizzlies back under the
protection of the Endangered Species Act.
In all, officials
tallied 25 known and probable grizzly mortalities. Twenty-two were
human-caused, two resulted from natural causes, and the reason for one
death was undetermined. Aside from management removals, for every bear
that is reported dead, two more likely went unreported, according to
Schwartz.
“This is not a good year for bears as far as mortality is concerned,” said Schwartz.
Schwartz
reported this year’s results at the annual meeting of the Yellowstone
Grizzly Coordinating Committee at Snow King in Jackson last week.
Nine
female grizzlies over 2 years of age were among the reported dead:
three from management actions, four from hunting incidents, and two
from natural causes.
Wildlife managers say these so-called “independent-age females” have the biggest impact on the grizzly populations.
But
Schwartz said the total grizzly population estimate of 571 bears is
likely low. “As bears increase in this ecosystem, we’re likely
underestimating what is out there,” he said. Statisticians and
biologists are working on a new formula for counting the animals.
Further, Schwartz says one year of high mortality among females does not constitute a crisis.
“We
have exceeded sustainable mortality limits in the past,” he said. “When
we have a year like this, typically the mortality levels drop down
again.”
Schwartz said his study team uses models that let
researchers look at estimated female survival. “Through 2003, we’ve
shown a very slight increase in female survival, which sort of shows
that all of the programs to keep females alive are working,” he said.
“Our major concern through all of this is that we don’t allow the bear
population to decline because of humans.”
Louisa Willcox,
director of the Natural Resource Defense Council’s wild bears project,
said the high mortality among females is just one more reason why
grizzlies should remain protected under the federal endangered species
law.
“The very first year, just months after delisting, we have a problem,” she said.
A
lack of natural food in 2007 has created a “perfect storm” for grizzly
conflicts and mortalities, according to Willcox. Droughts and late
frosts have hurt berry crops, mild winters have yielded fewer animal
carcasses, mountain pine beetles and blister rust have robbed forests
of whitebark pine trees, and lake trout have caused declines in
Yellowstone’s cutthroat trout populations.
The Natural Resources
Defense Council is one of several conservation groups that have filed a
lawsuit against the grizzly delisting.
Schwartz agreed that a
decline in natural food sources is cause for worry but said individual
bears seem nutritionally sound. The study team uses electrodes placed
on a captured bear’s nose and tail to measure body fat, similar to the
system that is used on Olympic athletes.
“Bears going into the
den in the autumn are around 30 percent body fat,” he said. “We’ve
measured that every year since 2000. You let the health of the animal
tell you about how healthy the environment is.”
“If food is
limited, then you wouldn’t expect the bear to get fat,” Schwartz
continued. “If the environment were to change and food were less
abundant, then we can detect it. If we began to see a downward trend,
that would be indicative that the bears are not meeting this nutrition
requirement.”
Schwartz said most bears would spend more time eating alternative foods during years when their traditional fare is meager.
However,
eating different foods doesn’t solve the problem. For example, a
positive relationship exists between whitebark pine seed production and
grizzly bear birth rates, Schwartz said.
Researchers with the
Interagency Grizzly Bear Study Team and elsewhere are currently
conducting habitat surveys to see how mountain pine beetles and blister
rust are affecting the whitebark pine tree population.
Further, biologists are looking at other food sources like cutthroat trout, army cutworm moths, and elk carcasses.
For
instance, cub and yearling survival seems to be a little better in
years following winters with heavy snowfall. Last winter, which saw
light snowfall, elk carcasses were only found every 0.14 kilometers on
certain survey transcets.
Bears are attracted to carcasses in
the spring. When there aren’t a lot, bears will congregate around those
available. Since large male grizzlies are known to kill cubs, sharing
carcasses could result in lower cub survival.
“Those offspring
are a little more vulnerable than if she had her own carcass and he had
another carcass off to himself,” he said outlining a scene of a mother
with cubs sharing a carcass with an adult male.
As for
Yellowstone cutthroat, fisheries biologists measuring spawning fish in
Clear Creek, a tributary of Yellowstone Lake, found only 500 fish this
spring compared to upwards of 60,000 fish in the 1970s.
“The
bears aren’t using the streams the way the used to,” Schwartz said.
Most bears have switched from streams to elk calving areas.
“It’s mostly male bears that are eating fish, not female bears,” he said.
Yellowstone
officials are currently using gill nets to catch and kill lake trout in
Yellowstone Lake. With more 270,000 fish harvested over the past
several years, biologists expect the cutthroat population to rebound.
“If things hold, we can anticipate that there are going to be more fish available,” Schwartz said.
Army
cutworm moth supplies, another important food source for grizzlies,
seem to be holding steady. In 2007, researchers documented 253 bears in
172 groups at 51 confirmed and possible moth sites. Though not all of
those 253 are different bears, Schwartz said the food source seems
intact.
“As near as we can tell, moth numbers are probably
holding up just fine,” he said. “We’re seeing a continued use of moth
sites in this ecosystem.”
