Cottontails in Massachusetts
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%).
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
Historically, New England cottontails were present in all 14 counties of Massachusetts. Prior to 1930, this was 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 mid-west and released. Another 4600 were raised at a state propagation facility and released. Eastern cottontails are now known to occur in all of Massachusetts' 14 counties.
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.
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.
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.
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.
Landowners interested in managing their land for New England cottontails (and other wildlife which depend on similar habitats) can download A Landowner's Guide to New England Cottontail Habitat Management (17 MB) , published by the Environmental Defense Fund.
Cottontails, like many other wild animals, can thrive in suburban and urban areas. These rabbits may do considerable damage to flowers, vegetables, trees and shrubs, in situations ranging from home garden plots to large commercial operations. They eat a wide range of flowers including new tulip shoots. These rabbits will also eat most vegetables, although they usually ignore corn, squash, cucumbers, tomatoes, and potatoes. Cottontails also gnaw the bark or clip branches of home landscaping, orchards, forest seedlings, and park trees and shrubs. Plants of the rose family, including apples, blackberries, and raspberries seem to be preferred. They damage a wide variety of deciduous shade and ornamental trees and even chew on evergreen trees.
- Fencing: One of the best means to protect your backyard garden or berry patch is to put up a small fence. A low fence of 2-foot chicken wire with 1-inch or smaller mesh is sufficient. Be sure that the bottom is tight against the ground, or buried a few inches deep, as cottontails may otherwise try to push under it. The chicken wire may be rolled up and stored during winter to prevent it from deteriorating. Larger, more permanent fences of welded wire or chain link are costly but last longer.
- Tree Guards: Cylinders of ¼-inch hardware cloth 18-20 inches high will protect young trees from damage. Remember that the cylinders must extend high enough to be above the rabbit's reach when the animal is standing on snow. The cylinder should stick out at least 1-2 inches beyond the trunk or stem of the protected tree or shrub. Some commercial tree guards or tree wrap may also be useful, but rabbits will chew through tree wrap if food is in short supply.
- Wire Cages: A small dome or cage of chicken wire placed over a flower bed will protect tulips and other vulnerable flowers until they are large enough to be ignored by the rabbits.
- Repellents: Several commercial repellents can discourage browsing by cottontails. Most are contact or taste repellents which render the treated plants distasteful to the rabbits. Some repellents are poisonous and require safe use and storage. Check with the Massachusetts Pesticide Bureau for information on the legal use of repellents. Mothballs or dried blood meal are sometimes used as odor repellents to keep rabbits away from the treated area. However, the efficacy of these products is often quite variable, depending on the behavior and abundance of rabbits and the availability of alternative foods.
- Trapping: Cottontails can often be captured in wooden or wire box traps, about 24 inches in length, and 10 inches in height. Apples, carrots, or cabbage are good warm weather baits. Wire traps are more effective when covered with canvas or other dark material. Remember that wildlife may not be relocated in Massachusetts. In good habitats, other rabbits will quickly replace those which are trapped.
- Shooting: Shooting is quick, simple, and effective in rural areas where firearms discharge is safe and lawful. This may be most effective when targeting a few persistent animals.
- Frightening: Most home remedies, such as predator decoys, mirrors, noisemakers, balloons, or other devices are of dubious effectiveness. These gimmicks may work for a short time, or on individual animals, but should not be relied on. Rabbits will habituate to the presence of these items and will soon disregard them.
Cottontails are an important natural resource in Massachusetts. They
are classified as a game species, for which established regulated hunting
seasons exist. If you are experiencing problems with, or have questions
regarding cottontails, contact your nearest MassWildlife
District office. Further information
on other wildlife is also available.
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. Some surveys also analyze DNA in rabbit pellets. 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.
Past Rabbit Research
- From 1950 to 1952, graduate students at the University of Massachusetts, working with the Division of Fisheries & Wildlife (MassWildlife), collected 938 cottontails from throughout Massachusetts. Site specific data remain available for 654 (70%) of these, which include 508 (78%) Eastern cottontails from 13 counties and 146 (22%) New England cottontails from 11 counties.
- From 1960-62, another student collected 337 (62%) Eastern cottontails and 207 (38%) New England cottontails, mostly from within a 20-mile radius of Amherst, Hampshire County, including parts of both Franklin and Hampshire counties.
- In 1970-72, a third cooperating student collected 36 cottontails in Massachusetts as part of a regional study. These included 28 (78%) Eastern cottontails from 5 counties and 8 (22%) New England cottontails from 3 counties.
- MassWildlife biologists conducted a fourth survey during 1979-81, principally collecting specimens from cooperating hunters. They received 401 (78%) Eastern cottontails from 13 counties and 114 (22%) New England cottontails from 7 counties.
- The next MassWildlife survey, in 1991-93, received 967 cottontails, mostly from hunters. These included 929 (96%) Eastern cottontails from 13 counties and 38 (4%) New England cottontails from 6 counties. The sample may have been skewed due to the lack of participants in some counties; however, the predominance of Eastern cottontails is apparent.
- In 2000-2003, 183 cottontails were received from 9 counties. All specimens were Eastern cottontails. However, outside the survey period, New England cottontails were confirmed from Barnstable, Berkshire, and Hampden counties.
- Chapman, J.A., J.G. Hockman, and W.R. Edwards. 1982. Cottontails. Pages 83-123 in J.A. Chapman and G.A. Feldhamer, eds. Wild mammals of North America. Biology, Economics, Management. Johns Hopkins Press, Baltimore, 1147pp.
- DeGraaf, R.M. and M. Yamasaki. 2001. New England wildlife: habitat, natural history, and distribution. Univ. Press of New England, Hanover, N.H., 482pp.
- Godin, A.J. 1977. Wild mammals of New England. Johns Hopkins Press, Baltimore, 304pp.
- Wilson, D.E. and S. Ruff, eds. 1999. The Smithsonian book of North American mammals. Smithsonian Institution Press, Washington, D.C., 750pp.