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Bald eagles, grizzly bears, Canada lynx, and gray wolves are the only known species to occur within the affected area that are protected by the Endangered Species Act. Wolverine and trumpeter swan, U.S. Forest Service sensitive species, could also occur in the affected area. These species could be directly affected by bison management actions, such as shooting, hazing, or habitat loss or modification. Because bison are an important food source, predatory species could also be indirectly affected by reduced foraging opportunities caused by changes in bison numbers, distribution, and seasonal migration patterns. The agencies prepared a biological assessment for the modified preferred alternative and sent it to the U.S. Fish and Wildlife Service. The letter of concurrence from the U.S. Fish and Wildlife Service can be found in appendix J of volume 1.

Bald Eagles. Alternatives 5 and 6 would negatively affect bald eagles that winter and nest near Seven-Mile Bridge because of the location of a capture facility in this area. Other bald eagles in the analysis area would be protected by avoiding their nesting and wintering areas. Change in bison carrion availability would have a negligible effect because it is only a small part of the bald eagle diet. The modified preferred alternative may have a minor positive effect on bald eagles, particularly those nesting on Horse Butte, as a result of the potential for less hazing, capture, and handling of bison than under the no-action alternative.

Grizzly Bears. All alternatives could potentially disturb or displace grizzly bears from areas near bison management activities. The alternatives would affect only a small part of the Greater Yellowstone Grizzly Bear Recovery Zone, an area where seasonal or year-long grizzly activity is common and contains habitats important to the recovery of grizzly bears. Denning bears would not be affected during the winter when most activities would occur. Under alternatives 3, 4, and 7, increased human activity could increase the probability for human/bear conflicts and bear mortality. This probability would be reduced to negligible by educating hunters, removing gut piles, and implementing other mitigating measures.

The degree to which an alternative modifies bison population numbers could likewise affect grizzly bears. Bison, along with other ungulates, rank as one of the highest sources of net digestible energy for grizzly bears in the Yellowstone ecosystem. Bison are particularly important to bears because they provide a high quality food source during early spring before most vegetal foods are available to bears. From March through May, ungulates, mostly elk and bison carrion, are the most important foods in the grizzly bear’s diet (Mattson et al. 1991). Grizzly bears that den in the Pelican and HaydenValleys in the park depend on bison carrion and are most likely to be affected by changes in bison populations.

 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 (Smith 2000).

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.

Canada Lynx. Canada 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 Forest if 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.