Under alternative 1,
bison numbers would not be maintained within a specific range, and low
population levels could result during some periods. Consequently, foraging opportunities
could be reduced during some years and negatively impact grizzly bears, particularly
during the spring. This impact would likely be negligible unless bison
disappeared from Pelican or Hayden Valleys
in the park. Alternative 2 would allow the bison population to reach a
long-term maximum of 3,500 bison quickly, and would leave park roads ungroomed,
which would likely increase winter bison mortalities and carrion in the park.
This would increase the availability of bison as a food source and moderately
benefit grizzly bears. Alternative 3 would have minor benefits. Alternatives 4,
6, and 7 would maintain the bison populations within a specific range and cause
only minor changes in the population. Thus, the impacts on grizzly bear
foraging opportunities would be negligible. Alternative 5 would cause a major
decrease in the first few years in the bison population and reduce the carrion
supply available to grizzly bears. The modified
preferred alternative would result in bison populations similar enough to those
under alternative 1 that it is not likely to adversely affect the grizzly bear.
Gray Wolves. The Rocky Mountain
gray wolf was reintroduced in Yellowstone
National Park in March 1995 and is
part of a “nonessential experimental population.” This means that the species
is listed and protected under the Endangered Species Act, but agencies have
additional flexibility in their management. At this
time, 11 named packs of wolves exist in the Greater Yellowstone Area (8
breeding pairs existed in 1999), as well as an additional 115 to 120 wolves
living independently in the Greater Yellowstone Area as pairs or individuals
All alternatives could disturb or displace wolves from areas near bison
management activities. However, any impact on the small wolf population would
likely be negligible.
Wolves prey primarily on elk, moose, and deer. These species are abundant in
the analysis area, and usually account for more than 90% of the biomass
consumed. Smaller mammals may be an important alternative food during the
snow-free months. Wolves rarely prey on live bison, but do eat bison carrion if
it is available. Although wolves could eventually increase their take of bison
as prey as the wolf population increased, impacts from changes in the bison
population during the 15 years this plan was in effect would be negligible in
alternatives 1, 3, 4, 6, 7, and the modified
preferred alternative. Alternative 2 would have a moderate beneficial
impact and alternative 5 a moderate to major adverse impact to wolves through
larger-scale changes in bison population numbers.
On December 12, 1997, the
United States District Court for the District of Wyoming ruled that the gray
wolf reintroduction program in Yellowstone
National Park and northern Idaho
violated one provision of the Endangered Species Act. The court ordered the
federal government to remove the reintroduced wolves and their offspring. On January 13, 2000, this decision was overturned by the 10th U.S. Circuit
Court of Appeals.
lynx are very susceptible to some human
activities. All the alternatives could displace or disturb lynx from areas near
bison management activities. Under alternatives 2, 5, and 6, snowmobile use now
on the groomed trails inside the park would be displaced to trails and
off-trail areas in the neighboring Gallatin
National Forest where lynx occur.
Lynx are specialized predators that may face competition from generalist
predators given access to their habitat by following packed-snow routes such as
those resulting from snowmobile use. Winter recreation activities would be
monitored on the national forest and, if necessary, mitigating measures
implemented to lynx. Changes in bison numbers would have a negligible impact
because lynx seldom feed on bison carrion.
Wolverines. Impacts very similar to those
described for lynx could also affect wolverines. These include displacement or
disturbance from bison management activities or increased snowmobile activity
in the Gallatin National
alternative 2, 5, or 6 were implemented.
Trumpeter Swans. Trumpeter swans could be affected by the location
and operation of bison management facilities. The swan occupies meadows and
open fields, plus lakes, ponds, or slow-moving water inside the park on the Madison
River. In particular, a breeding pair at Seven-Mile
Bridge where a capture facility is
proposed in alternative 6, would experience major adverse impacts from
construction and operation.