Wolf-moose interaction on Isle Royale: The end of natural regulation?

Long-term population fluctuations of wolves and moose in Isle Royale Nation al Park, Michigan, are used to evaluate a central tenet of the "natural reg ulation" concept commonly applied by the National Park Service (NPS) in the United States, namely, that wild cervid populations exhibit density depend ence which, even in the absence of large predators, will stabilize populati on growth. This tenet, restated as a hypothesis, is rejected based on moose population response to a chronic wolf decline. In 1980-1996 with wolf numb ers down, partly due to introduced disease, moose numbers increased to a hi storic high level. There was insufficient density dependence in moose repro duction and mortality to stabilize moose numbers. In 1996 moose suffered a crash; 80% died, primarily from starvation. These fluctuations, along with the possibility that the highly inbred wolf population may become extinct, will challenge NPS policy. The long-standing NPS management tradition of no nintervention may not be compatible with the current policy that stresses m aintenance of natural ecological processes, such as a predator-prey system.