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

Abstract

J 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 Soule 1999). Today in northeastern North America, the top terrestrial predator is the coyote, Canis latrans, an immigrant to the region that is anything but rare. Historically, the species was unknown to European settlers of eastern North America, who were more concerned with the presence of wolves and cougars. Coyotes were a predator of the Great Plains. Lewis and Clark didn’t catch their first glimpse of a coyote until 1804, when they reached the eastern edge of present-day Nebraska (Ambrose 1996). Times have changed. Over the past two centuries the coyote has dramatically expanded its geographical range and is now ubiquitous throughout northeastern North America (Figure 1; Parker 1995, Gompper 2002). It has even colonized seemingly isolated geographical regions such as Cape Cod and the Elizabeth Islands of Massachusetts, Cape Breton Island, Prince Edward Island, and Newfoundland of Atlantic Canada, as well as urban habitats such as parts of New York City. The culmination of this range expansion may arguably be the capture of a wild coyote in Central Park in the heart of Manhattan in 1999 (Martin 1999).