Mortality patterns and population sinks for Yellowstone grizzly bears, 1973-1985

摘要: Yellowstone National Park and the surrounding national forests support one of few remaining grizzly bear (Ursus arctos horribilis) populations in coterminous United States. The area attracts >2 million tourists annually, permanent communities both out park cater to their needs. Many outfitters provide access for recreation hunting areas adjacent park. Furthermore, cattle sheep graze extensively nearby areas. Grizzly bears, because omnivorous food habits, natural aggressiveness, ability move long distances, will likely find any human habitation within home range obtain there if possible. Once a secures successfully at particular location, that place becomes an important part its may be checked periodically more (Stokes 1970, Meagher Phillips 1983). Bears are tolerated even encouraged seek some locations. However, most settlements they usually removed by appropriate authorities. These sites become "population sinks," bring bears into contact with humans, often resulting removal from population. Evaluating population sinks as sources mortality requires consideration spatial temporal components, including locations trouble spots, movements seasonal changes, age-specific mortality. Adult females constitute crucial component dynamics, difference between recovering declining toward extinction amounts loss 1-2 adult females/year (Knight Eberhardt 1984, 1985). sex age distribution deaths magnitude losses relation recruitment key issues evaluating trends. Because grizzlies effectively isolated other populations, depends solely on reproduction, which has been relatively low available evidence indicates exceeded after about best prospect reversing apparent downward trend 23%/year is reducing mortality, particularly females. In this paper, we document location sinks, suggest factors influence these sites. We focus females, but use records segments needed.