This study seeks to document lifelong survival patterns for moose in Isle Royale National Park, Michigan, and to assess resulting impacts on adjacent trophic levels. The study is based on the hypothesis that nutritional plane of moose in winter largely determines lifelong survivorship for moose, which then determines wolf food level and ultimately wolf density. The level of radiocarbon (14C) in moose bones and teeth collected at Isle Royale since 1958 will be used to determine year of birth, based on a sharp historical peak in 14C which resulted from atmospheric nuclear weapons tests in the 1950s and early 1960s. Using the 14C dating technique, data from almost 1,400 Isle Royale moose alive during the past 3 decades will be used to track changes in cohort survival pattern and population age structure. When combined with existing data on moose vulnerability, the results are predicted to explain long-term fluctuations in wolf density. Moose population simulations and actual wolf population responses in 1988-1990 will test the hypothesis that lifelong survival in moose is a key link between 3 trophic levels (wolf, moose, and vegetation) in this simple community. There have been no comparable analyses of multi-level trophic interactions involving large mammals, so results will be useful in both theory and application. This study will also prompt more widespread use of radiocarbon dating techniques in animal population studies and other natural sciences.
