Environmental Engineering Reference
In-Depth Information
8
Sustaining Biodiversity:
The Ecosystem Approach
Land
Forest
Renewal
Biodiversity
CASE STUDY
Reintroducing Wolves
to Yellowstone
wolves would attack their cattle and sheep; one en-
raged rancher said that the idea was “like reintroduc-
ing smallpox.” Other objections came from hunters
who feared the wolves would kill too many big-game
animals, and from mining and logging companies that
worried the government would halt their operations
on wolf-populated federal lands.
Since 1995, federal wildlife officials have caught
gray wolves in Canada and relocated them in
Yellowstone National Park and northern Idaho. By
2005, about 850 gray wolves lived
in or around these two areas.
With wolves around, elk are
gathering less near streams and
rivers. Their diminished pres-
ence has spurred the growth of
aspen and willow trees that at-
tract beavers. And leftovers of elk
killed by wolves are an impor-
tant food source for grizzly bears.
The wolves have also cut
coyote populations in half. This
has increased populations of
smaller animals such as ground
squirrels and foxes hunted by
coyotes, providing more food for
eagles and hawks. Between 1995
and 2002, the wolves also killed
792 sheep, 278 cattle, and 62
dogs in the Northern Rockies.
In 2004, the U.S. Fish and
Wildlife Service (USFWS)
proposed removing wolves
from protection under the
Endangered Species Act in Idaho
and Montana. Private citizens in
these states could then kill
wolves that attack livestock or
pets on private lands. Conserva-
tionists say this action is prema-
ture, warning that it could undermine one of the na-
tion's most successful conservation efforts.
Population growth, economic development, and
poverty are exerting increasing pressure on the
world's forests, grasslands, parks, wilderness, oceans,
rivers, and other storehouses of biodiversity, a topic
explored in this chapter.
At one time, the gray wolf, also known as the eastern
timber wolf (Figure 8-1), roamed over most of North
America. Then between 1850 and 1900, an estimated
2 million wolves were shot, trapped, and poisoned by
ranchers, hunters, and government employees. The
idea was to make the West and the
Great Plains safe for livestock and
for big-game animals prized by
hunters.
It worked. When Congress
passed the U.S. Endangered
Species Act in 1973, only about
400-500 gray wolves remained in
the lower 48 states, primarily in
Minnesota and Michigan. In 1974,
the U.S. Fish and Wildlife Service
(USFWS) listed the gray wolf as
endangered in all 48 lower states
except Minnesota.
Ecologists recognize the im-
portant role this keystone predator
species once played in parts of the
West and the Great Plains. These
wolves culled herds of bison, elk,
caribou, and mule deer, and kept
down coyote populations. They
also provided uneaten meat for
scavengers such as ravens, bald
eagles, ermines, and foxes.
In recent years, herds of elk,
moose, and antelope have ex-
panded. Their larger numbers
have devastated some vegetation,
increased erosion, and threatened
the niches of other wildlife species.
Reintroducing a keystone species such as the gray
wolf into a terrestrial ecosystem is one way to help
sustain the biodiversity of the ecosystem and prevent
further environmental degradation.
In 1987, the USFWS proposed reintroducing gray
wolves into the Yellowstone ecosystem. The sugges-
tion brought angry protests. Some ranchers feared the
Figure 8-1
Natural capital restoration:
the
gray
wolf
. Ranchers, hunters, miners, and loggers have
vigorously opposed efforts to return this keystone
species to its former habitat in the Yellowstone Na-
tional Park—which is bigger than the U.S. states of
Delaware and Rhode Island combined. Wolves were
reintroduced beginning in 1995 and now number
around 850.
