Trophic web and resource cycle for Isle Royale Figure 3 from Schlesinger et al. A much higher proportion of plant biomass can be consumed by ungulate grazers than by ungulate browsers, which depend on the annual growth of twigs and buds of woody shrubs.
The grizzly bear population in the GYE has increased dramatically since the s, although the bears are still listed as threatened under provisions of the Endangered Species Act. Currently very rare but in some places increasing since wolf reintroduction, willow and aspen are important for many bird species, small mammals, beavers, and moose.
Mule deer are abundant, numbering about orbut they migrate out of the park in winter, escaping some of the most intense wolf predation. In contrast to most predictions based on modeling, Messier and colleagues suggested that elk might decline substantially following wolf recovery because of the number of predator species involved.
This stumbling block may be particularly troublesome in the complex Yellowstone ecosystem; the need to design research hypotheses that discriminate among potential competing causes is therefore very real.
Moose no longer number on Isle Royale, as they did before wolves Allenso will elk ever exceed 19, as they did before wolves and after the artificial reductions in Yellowstone? In a world where species are becoming extinct on a daily basis, this rare relationship has endured and that should be given a lot of weight when making the decision of what to do about the wolf-moose problem on Isle Royale.
For example, in January researchers watched as a lone female wolf entered the territory of one of the wolf bands they had dubbed the Middle Pack.
The National Park Service faces a thorny set of choices to either intervene or let nature take its course. Some predicted that wolves would reduce coyotes and that the coyote reduction would affect other species YNP et al.