Background and Natural History
Here in the Bay State, there are two species of cottontail rabbits, the New England cottontail (Sylvilagus transitionalis) and the Eastern cottontail (Sylvilagus floridanus). You can't tell these rabbits apart by looking at them in the field. The differences can be determined with certainty only by skull characteristics and measurements and by DNA techniques. Generally speaking, however, New England cottontails have a slightly shorter ears (avg. 57mm) and smaller bodies (avg. 958 g) than Eastern cottontails (avg. 61mm and 1136 g). New England cottontails have a black spot between the ears about 90% of the time (40% in Eastern). They lack a white spot on the forehead (Easterns have a spot 43% of the time). New England Cottontails typically (95%) have a black line on the front edge of the ear (Easterns 40%).

Historic Background
The New England cottontail was first described as a species in 1895 from a Connecticut specimen. It is the only cottontail species native to the Northeast. The species has now been split into two, with the newly-described Appalachian cottontail (Sylvilagus obscurus) inhabiting the Appalachian Mountains from New York to Georgia and Alabama, and the New England cottontail found from the Hudson River Valley of New York through central and southern New England. During the last 25-50 years, New England cottontails appear to have decreased sharply in numbers and distribution over most of their range. It is listed as a species of regional conservation concern throughout the Northeast based upon threats to its survival, lack of data, limited range, and other special concerns. In June 2004, the U.S. Fish & Wildlife Service (USFWS) found that there was substantial need for protection of the New England cottontail under the U.S. Endangered Species Act and initiated a review. In 2006, the USFWS determined that federal listing was warranted but precluded due to other listing priorities. However, the New England cottontail was given the highest listing priority in the Northeast. Further action is pending.

Distribution and Introductions

Why Are Cottontail Populations Changing?
Populations of New England cottontails are in decline due to the destruction or modification of favorable habitat, to displacement by the highly adaptable Eastern cottontail, and to increases in medium-sized predators (skunks, raccoons, coyotes). Several subspecies of Eastern cottontails were introduced to the northeast in the 1920's and 1930's. These rabbits developed into established populations showing a high degree of hybrid vigor and ability to exploit a wide range of habitats. Perhaps, in the scramble to occupy new patches of early successional scrubland habitat, Eastern cottontails have been able to move into and exploit these sites more quickly than the New England species.

BREEDING

Eastern cottontails reach sexual maturity at 2-3 months of age. The breeding period is from March to September, but most commonly it is April to September. The gestation period averages 28 days, with an average litter size 5 to 6 young (range: 3-8). There may be 3 to 4 litters per year. The young leave the nest at about 3 to 5 weeks of age. The female does not dig the burrow, but uses an abandoned woodchuck den or excavates a shallow depression in soft earth in dense vegetation. New England cottontails probably become sexually mature during their second year. The breeding period is from March to July, occasionally continuing to September. The gestation period is 28 days, with the litter size averaging 5 (range: 3-8). There are 2 or 3 litters per year.

Habitat

Eastern cottontails favor farmlands, pastures, old fields, open woodlands, shrubby areas or brush piles along fence rows and stone walls, swamps and marshes, and suburban backyards with a mixture of grassland and shrubby cover. These cottontails avoid dense forests. New England cottontails appear to prefer brushy areas, woodlands with an open understory, shrub-dominated wetlands, and mountainous areas. They may also be found in regenerating clearcuts, shrublands, dense coniferous areas, or powerline corridors andhighway medians with dense coniferous habitat. Closely spaced patches of dense vegetation, 25 acres or larger, with stem sizes at least 20 inches tall and less than 3 inches in diameter, are favored.

Home Range, Activity, and Food Habits
New England cottontails have home ranges between 0.5 to 8.3 acres. Males have larger home ranges than females. These cottontails are active at dawn and dusk or at night, with most feeding in the few hours after sunrise or sunset. They feed on tender grasses and herbs in spring and summer, while utilizing the bark, twigs, and buds of shrubs and young trees in winter. Home ranges of Eastern cottontails range from about 0.5 to 40 acres. Adult males have larger home ranges than do females. Like New England cottontails, they are active at dawn, dusk, and early evening. They feed on grasses and herbaceous plants in summer, and woody seedlings, bark, twigs, and buds in winter.

Habitat Management
Biologists believe that the New England cottontail historically occupied dense understory vegetation associated with gaps in the forest, regenerating forest stands in disturbed areas, stream corridors, and shrubby woodlands. The fragmentation of these habitats may increase the vulnerability of New England cottontails to predation and may also increase competition for disturbed or early successional patches of land. These patches of thickets are highly threatened key components of the New England landscape and management of early successional and thicket habitats is essential to perpetuating a variety of thicket-dependent species. Conventional rabbit management techniques which focused on fields and pasture-lands have not been successful in either creating or maintaining habitats favorable to the New England cottontail and unfavorable to the Eastern cottontail. However, some biologists suggest that a habitat management regime which maintains patches of early successional habitats may be sufficient to maintain local populations of New England cottontails.

Perpetuation of the New England cottontail as a viable species in Massachusetts may additionally be enhanced by the creation of Eastern cottontail-free reserves until such times as these habitat techniques and practices can be widely implemented. New England cottontails have been introduced to one of the Boston Harbor Islands, and other islands are being contemplated as release sites.