Top Carnivores in the Suburbs? Ecological and Conservation Issues Raised by Colonization of North eastern North America by Coyotes

Abstract

Just a handful of individual members of a population of top predators—wolves and tigers, orcas, and great white sharks, for example—hold the potential to disproportionately influence animal and plant communities. The importance of this phenomenon, known as a “top-down” effect, has been demonstrated in several recent studies. For example, as few as four killer whales may be responsible for a shift in 800 kilometers of Alaskan near-shore community structure, from a structure dominated by kelp forests with few herbivores to one with high numbers of sea urchins and low kelp densities (Estes et al. 1998). Similarly, just two or three wolf packs indirectly control tree community organization by regulating moose numbers in 544-km2 Isle Royale, Michigan (Post et al. 1999). In coastal southern California, the presence or absence of coyotes in patches of sage–scrub habitat directly controls the distribution and abundance of smaller carnivores, which in turn alter scrub-breeding bird communities (Crooks and Soulé 1999).