Competing Cottontails

Two Kinds of Cottontails

New England and Eastern cottontails look very much alike.

Eastern cottontails' larger eyes give them an advantage over brush-dwelling New England cottontails./L. Gorman/USFWS

But one key difference gives the introduced Eastern species an edge over the native New England rabbit: the eyes of Eastern cottontails are half again as large as those of New England cottontails. This physical trait likely arose because Eastern cottontails evolved in more-open habitats, where detecting predators at a distance conferred a strong survival advantage.

New England cottontails are a forest species that depends on areas of thick shrubs and young trees that grow up following disturbances such as fires, hurricanes, and flooding. A woodland creature living in thick habitat has less of a need to spot predators at long distances, which is probably why the New England cottontail did not develop eyes as large or far-seeing as those of the Eastern cottontail.

Biologists believe that their larger eyes and sharper vision lets Eastern cottontails venture farther from protective cover while remaining able to spot and evade predators. Eastern cottontails seem better able to survive in the fragmented habitats of southern New England, including open fields, forest edges, small thickets, and even golf courses and suburban lawns. In many smaller habitat patches, Eastern cottontails have replaced New England cottontails. Eastern cottontails probably do not directly oust New England cottontails from such areas: They may simply be able to survive in habitats that New England cottontails cannot use, and they may be better able to find and occupy new habitats as they become available.