Yosemite Natioanl Park: Wildlife
Beers
Yosemite National Park is home to 300 - 500 American black
bears, Ursus americanus. Although usually referred to as the
black bear, very few are black, and they are more likely to
be found in a variety of colors ranging from black to brown,
blond, or cinnamon.
Black bears are omnivores and will eat almost anything. They
spend most of their days foraging for grasses, seeds, berries,
acorns, and insects and occasionally feed on carrion. Bears
tear open rotten logs or old stumps in search of insect larvae.
Meadows also furnish a wide variety of food, such as grass,
clover, lily, wild onion, and brodiaea bulbs. Research in
Yosemite shows that plants, including acorns, comprise 75%
of the diet of Yosemite bears. Bears are also fond of fruit,
particularly manzanita, service berry, elderberry, and wild
cherry. Chipmunks, ground squirrels, marmot, pocket gophers,
and mice are also a part of their diet. In the fall, bears
are often seen beneath oak trees searching for acorns. Unfortunately,
many Yosemite bears have also perfected the skill of obtaining
food from humans.
Bears are also opportunists which means that they can easily
adapt to new foraging habitats, from meadows to manzanita
bushes, from cars to picnic coolers. Opportunism is often
seen as an indication of intelligence in animals and most
researchers agree that bears are highly intelligent. Anyone
who has lost food to a bear learns that a bear's strength
and intelligence should never be underestimated. This enterprising
nature of the black bear can be linked to the fact that cubs
stay with their mothers for well over a year after birth.
This allows mother bears time to teach cubs survival techniques
that directly relate to opportunism. It is this characteristic
which allows cubs to learn from their mothers how to break
into cars for food.
The biggest threat to the survival of the black bear in Yosemite
is the availability of human food; in cars, campgrounds, picnic
areas, and the wilderness. Once a bear is rewarded by obtaining
human food, it will often continue to seek it out and some
may even resort to intimidating humans in order to get more.
As their natural fear of people fades, they may become more
aggressive. When they become too aggressive and human safety
is threatened, bears are sometimes killed by park rangers.
Obtaining human food alters the natural foraging habits, population
dynamics, biology, and behavior of bears. It is the ultimate
goal of wildlife managers is to have all bears in Yosemite
eating their natural diet, avoiding humans and our food altogether.
It is your responsibility to store food properly when visiting
Yosemite. Your actions can affect the lives of bears!
Bear biology
Black bears reach sexual maturity at the age of three. Males
and females stay together for only a few days when mating
occurs in June or July. Although black bears have a gestation
period of seven months, females do not show signs of pregnancy
until shortly before birth because they have a reproductive
adaptation called delayed implantation. The fertilized egg
does not attach to the females' uterine wall until autumn.
If food is scarce and a female is unable to put on sufficient
weight before hibernation, the fertilized egg will, as a result,
spontaneously abort.
A black bear litter consists of one to three cubs weighing
as little as half a pound each. The cubs immediately begin
to nurse on the female's high fat milk and emerge from the
den in early spring weighing as much as five pounds. The average
adult bear stands three feet at the shoulder, measures five
feet in length, and weighs between 200 and 300 pounds. However,
some of Yosemite's bears have tipped the scales at over 650
pounds!
During winter months when food sources are scarce, Yosemite's
black bears den in boulder caves and occasionally in the cavities
of large trees. By metabolizing the body fat stored throughout
the previous summer and fall they keep themselves warm. Black
bears in the Sierra Nevada do not truly hibernate, since their
body temperature and respiratory rate drop only slightly.
Studies show that black bears, in general, have the ability
to sleep for over five months without eating or eliminating
waste.
The rising temperatures of spring and summer make it necessary
for bears to concentrate on keeping themselves cool rather
than warm. To stay cool, bears construct day beds or nests,
usually in shady thickets or boulder piles. Much like dogs,
they push aside leaves and twigs as they dig down to cool
mineral soil. Black bears are most active during the crepuscular
hours of the day, that is, dawn and dusk. During the warmest
summer months, few bears are active during the day, becoming
more and more nocturnal as summer temperatures rise. Many
bears have found this cool, quiet time period to be the easiest
opportunity in which to forage for natural foods, and search
for human food because less people are present.
Perhaps no more than five bears co-existed within the granite
walls of Yosemite Valley prior to the settlement of non-native
people. But after more settlers and visitors began to live
in and visit Yosemite, it was common to see as many as 60
bears at a time rummaging through garbage at a popular spot
called Bear Hill. Back then, Yosemite bears were fed by rangers.
The visitors who photographed them saw the bears as being
synonymous with the park, and the bears themselves were quick
to learn that human contact meant food.
In the 1920s and 1930s, human-conditioned bears were beginning
to wreak havoc, injuring tourists and raiding restaurants
nightly. In 1925, the National Park Service began luring bears
away from restaurants and campsites with a trail of food scraps
leading to open pit garbage dumps. This bear feeding program
also attracted tourists who wanted to view bears close up.
Responding to visitor demand, the National Park Service then
designated a parking area and constructed bleacher seating
at the dump in Yosemite Valley. Bear related injuries increased
as people made attempts to get too close.
During the 1950s and 1960s, most of the open dumps in the
Valley were closed due to the increased aggression by bears,
which resulted in numerous visitor injuries. In 1971, the
last dumps in the park were permanently closed. Bears learned
quickly that they could get food from visitors staying in
campgrounds, tent cabins, and the wilderness. In 1975, the
National Park Service began a more comprehensive bear management
program including research, public education, better methods
of storing trash, and controlling problem bears. Many conditioned
bears were killed by the National Park Service during the
first years of this management program. Killing bears that
had become conditioned to human food was the only way to decrease
dangerous bear incidents. They could not be shipped off to
zoos--which were more interested in exotic species, nor relocated
outside the park, because surrounding U.S. Forest Service
land managers and private owners did not want to deal with
Yosemite's conditioned bears.
Unfortunately, many park visitors fail to understand the connection
between leaving food for bears, in cars, unattended in campsites,
in backpacks, and killing them. Widespread noncompliance with
food storage regulations causes bears to become conditioned
to human food, and to become a threat to human safety. Currently,
food-conditioned bears are captured, tagged, and relocated
to more remote bear habitat within the park. Most of these
bears find their way back, usually within one week. Bears
that continue to return and exhibit aggressive behavior must
often be euthanized. A new strategy has been to release the
bears where they were captured while subjecting them to a
very negative experience. The hope is that the bear will associate
that area with the negative experience and avoid it.
The goal of wildlife managers is to provide the park's black
bears a home where they can thrive in a natural condition,
dine on native plants and animals, and reach a normal life
expectancy. To achieve this, one thing must happen in Yosemite:
all human food, scented items, and garbage must be properly
stored where bears cannot get them. This goal has been made
possible with the help of the Yosemite Fund, which over the
past 10 years, has donated food storage lockers for every
park campsite, trailhead, parking lot, and rental tent camp.
In 1998, the Yosemite Association launched a backcountry food
storage program, and provided food canisters for hikers at
a nominal rental fee. This program was expanded in 1999 when
the Yosemite Association and Yosemite Concession Services
combined efforts. Now, every backpacker who leaves from a
Yosemite trailhead will have access to a canister for a $5.00
per trip rental fee. Also in 1999, Yosemite National Park
received a budget increase of $500,000 to increase visitor
education, enforcement of food storage regulations, cleanup
of trash, and additional wildlife management staff to work
with bears. Since 1999, incidences of bears obtaining human
food have plummeted, in large part because of increased cooperation
of park visitors in storing their food and trash properly.
As for the future of black bears in Yosemite, some look forward
to a day when seeing bears in developed areas is a rare occurrence.
So, just as some people marvel that one could see bears at
dumps in the park, perhaps some day people will marvel that
bears used to walk through campgrounds and parking lots. Instead,
those same visitors will hopefully see wild bears in their
natural settings.
California Bighorn Sheep
When pioneers came to this scenic area more than 100 years
ago, many hundreds of bighorns roamed these mountains. Soon
after, however, the California bighorn sheep were forced to
extinction in Yosemite National Park by hunting, diseases,
and the competition for food by domestic sheep. Today, through
the efforts of the National Park Service, U.S. Forest Service,
California Department of Fish and Game and the Yosemite Association,
the bighorns are once again part of Yosemite's wildlife population.
Found along the eastern edge of the park, the bighorns are
sometimes seen beside Highway 120 beyond Tuolumne Meadows.
Golden Eagle
The population of Golden Eagles, Aquila chrysaetos, within
the boundaries of Yosemite is doing well. Golden eagles are
not commonly seen in Yosemite Valley. They are superb fliers
and hunters. Look for their golden crown of feathers. Young
birds have white areas on wings and tails.
Great Gray Owl
Yosemite is home of the rare and endangered Great Gray Owl,
Strix nebulosa. A current study is underway documenting the
status, distribution, numbers, habits and health of the park
population of this large, noble species. In some areas of
the park you may hear their distinctive, deeply-toned hoot."
Coyote
This silver-grey member of the canine family is seen year
round. At night you may hear them singing in a chorus of howls,
barks and yodels. Coyotes, Canis latrans, are primarily predators
of field mice and squirrels, though they have learned to beg
from people. Please do not feed them, as human food is harmful
to them, they may bite and conditioning them to seek food
from people makes them vulnerable to being hit by passing
cars.
Mule Deer
All the deer in Yosemite are mule deer. Often seen in or near
meadows browsing or grazing, the naturally timid mule deer
have grown accustomed to seeing people. More attacks on humans
occur by deer than by bears. Though they appear to be tame
and may even approach you, the California mule deer is a wild
animal and will charge if cornered or threatened. Its hooves
and antlers are sharp. Always leave the deer a wide area to
walk away and, like all other animals in the park, never tempt
them with food.
Squirrels
A variety of tree and ground squirrels can be found throughout
Yosemite. One of the traditional favorites is the western
gray squirrel, Sciurus griseus. During mating season (twice
a year) they become animated, chasing one another, fighting
and making noise. Look for the impressive gray, bushy tail.
Steller's Jay
This comic, bright blue bird with pointed gray-black crest
has been dubbed the "camp robber" for the sly way
in which it steals a bit of food from a camp table. The distinctive
caw-like screech of the Steller's Jay, Cyanocitta stelleri,
is often an alert to others that food has been found.
Peregrine Falcon
An endangered species, the Peregrine Falcon has returned to
Yosemite Valley. Efforts by the National Park Service, Yosemite
Association and Santa Cruz Predatory Bird Research Group and
other organizations have augmented the population that reappeared
in the park in the late 1970's. The Peregrines, nesting in
Yosemite, are carefully watched and protected by the Park
Service.
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