Living With WildlifeCottontails in Massachusetts
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Background & Natural History InformationHere 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 by skull characteristics and measurements and by DNA techniques. Generally speaking, however, New England cottontails have a slightly shorter ear length (avg. 57mm) and a smaller body mass (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), always lack a white spot on the forehead (Easterns have a spot 43% of the time), and 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. At that time, it was the dominant-- if not the only--- cottontail species throughout 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. The closely related Appalachian cottontail (not found in New England) is also a species of concern, but has remained stable in some southern states. Distribution and Introductions: Based on the published literature and the examination of museum specimens, New England cottontails were historically present in all 14 counties of Massachusetts. Prior to 1930, New England cottontails were the only cottontail species appearing among 59 reports, except for 7 from Nantucket where Eastern cottontails were introduced as early as the 1880s. Between 1924 and 1941, however, at least 16,200 Eastern cottontails were imported from the midwest and released statewide. Another 4600 were raised at a state propagation facility and released. Eastern cottontails are now known to occur in all 14 counties. Why Are Cottontail Populations Changing? Studies in Connecticut, Massachusetts, New Hampshire, Pennsylvania, and Virginia have attempted to evaluate the New England and Appalachian cottontails' population status. Population declines are believed to be due to shrinkage of favorable habitat and to displacement by highly adaptable populations of the Eastern cottontail. Several subspecies of Eastern cottontails were introduced to the Northeast in the 1920s and 1930s. These rabbits developed into established populations showing a high degree of hybrid vigor and ability to exploit a wide range of habitats. It was formerly believed that New England cottontails were not sufficiently adaptable to resist this competition. However, a later study could not prove that competition with Eastern cottontails affected the decline of New England cottontails. Perhaps, in the scramble to occupy new patches of successional habitat, Eastern cottontails are 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 April to September. The gestation period averages 28 days, with the 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 its own 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 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, depending on habitat and geographical area. 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, depending on the specific habitat type and geographical area. 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. (Further habitat info.) 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. Cottontails are an Important Natural Resource in Massachusetts. Cottontails have an established harvest season and management program. If you have any questions regarding cottontail rabbits or would like to participate in collecting rabbit skulls for an important cottontail survey, contact the nearest MassWildlife regional office. Cottontail Rabbit Research
RABBIT RESEARCH Periodic surveys of the two cottontail species help biologists monitor changes in population status and distribution. These surveys are useful in evaluating long term trends. Survey methods such as hunter collections and road kills provide substantial information on distribution but the information is only as good as the amount of participation by interested people, and the geographic distribution of collected specimens and habitat sampling. When locations of rabbits are gleaned from the survey data, biologists will be able document habitats where New England cottontails are found. Wildlife managers can recommend or implement habitat management techniques to maintain conditions favorable to the species. Data from the surveys also provide a baseline for more detailed site-specific studies. Cottontail specimens collected are typically placed in museums for future study and reference.
Questions? Comments? Contact: Mass.Wildlife@state.ma.us Date Last Updated: August 23, 2005 MassWildlife Homepage
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