Two Kinds of Cottontails

Two kinds of cottontails inhabit much of southern New England and eastern New York: the native New England cottontail (Sylvilagus transitionalis) and the eastern cottontail (Sylvilagus floridanus), thousands of which were introduced into the region during the last century, brought in from states such as Missouri, Kansas, Oklahoma, and Texas.

Despite the fact that they are separate species, New England and eastern cottontails look much alike.

But one key difference may give the eastern cottontail an edge over the New England species where their ranges overlap: the eyes of an eastern cottontail are half again as large as those of a New England cottontail. This trait likely arose because eastern cottontails evolved in more-open grassland habitats, where detecting predators at a distance conferred a strong survival advantage.

The New England cottontail is primarily a forest species that depends on areas of thick shrubs and young trees that push up following natural disturbances such as wildfires, hurricanes, and flooding, as well as disturbances caused by human activities such as logging and farm abandonment. (Such habitat is sometimes called "early successional habitat" or young forest.) A woodland creature living in thick, tangled 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 as 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 small habitat patches, eastern cottontails have replaced New England cottontails.

Eastern cottontails probably do not 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 following natural or human-caused disturbances.

Biologists continue to study how both New England and eastern cottontails use different habitats, and how the presence of eastern cottontails may affect the ability of New England cottontails to use areas of habitat that conservationists create.