Nantucket’s fauna is very unique – maybe more so for what is not here than for what we have. Numerous species that are common elsewhere in New England are missing from our assemblage of terrestrial wildlife, including chipmunks, possums, raccoons, skunks, fox, woodchucks, and coyotes. What we do have on Nantucket are several species of small mammals and moles, squirrels (which were re-introduced to the island several decades ago by hitching a ride on a lumber truck), several species of bats (including a recently-discovered population of endangered northern long-eared bats) and two very common mammals- white-tailed deer and eastern cottontail rabbits.
Rabbits in particular are one of the most commonly observed wildlife species on the island- they graze on lawns, in gardens, under bird feeders and along road and bike path edges. Anyone who has driven around the island early in the morning has likely noticed the sheer number of road-killed rabbits, which are quickly “recycled” by nature’s undertakers – crows, gulls and vultures. The lack of previously-mentioned predatory mammals is likely a contributing factor to these high population numbers. What is not widely known is that Nantucket is also home to another very rare and elusive species of rabbit- the New England cottontail, our special “some bunny.”
The New England cottontail (Sylvilagus transitionalis) is the only cottontail rabbit native to the northeastern United States. It prefers dense shrubland habitats where it can effectively hide from predators, and for this reason is rarely seen. The more common eastern cottontail (Sylvilagus floridanus) looks virtually identical to the New England cottontail, but has a different number of chromosomes; therefore, the two species cannot interbreed. Eastern cottontails occur in shrubland habitats as well, but also frequent open grasslands, suburban yards, parks and fields. Because Nantucket was mostly open grassland habitat during colonial times due to extensive sheep grazing, New England cottontails were probably never numerous. Therefore, the eastern cottontail was introduced in the late 1800’s to provide game for hunters (along with snowshoe hares and black-eared jack rabbits, which are no longer common here). The eastern cottontail has since become our predominant local rabbit.
The U.S. Fish and Wildlife Service (USFWS) has placed high priority on locating sites where there are still viable populations of New England cottontails due to concerns regarding drastic declines across their range. Habitat loss was likely a major factor in these declines. Nantucket was identified as one of the most likely sites where remnant New England cottontail populations could still exist. This is because they were known to have once occurred here and there are vast expanses of highly suitable, undeveloped habitat currently available – most of which is within the island’s vast, protected conservation properties.
Starting in 2011, the Nantucket Conservation Foundation (NCF) Department of Science and Stewardship undertook an island-wide search for this species by conducting live trapping and tissue sampling combined with collecting fecal pellets (aka bunny poop). The best way to definitively distinguish between the two cottontail species is by DNA, which can be extracted from a pin drop of blood, a small tissue sample taken from the ear, or fresh fecal pellet collected on snow or frozen ground. Out of 216 samples collected over several years from many locations across the island and submitted to the University of Rhode Island for analysis, 11 tested positive as New England cottontails – all of which were collected from the Foundation’s Sanford Farm, Ram Pasture and the Woods property. This is significant information, as it indicates that there is a small but viable remnant population at this site. Prior to this discovery, the only locations within Massachusetts where New England cottontails were known to occur were Cape Cod and a small area in the southwestern Berkshires.
So why is this important? The New England cottontail has become extremely rare within the last 50 years. It was once found east of the Hudson River in New York, across all of Connecticut, Rhode Island and Massachusetts, north to southern Vermont and New Hampshire, and into southern Maine. This former range is believed to have declined by over 75 percent. This trend is attributed to the introduction of the eastern cottontail as well as the region-wide decline of its preferred dense shrubland habitat. On Nantucket, these dense shrublands are rare priority habitats in and of themselves that support other rare species such as northern harriers, eastern whip-poor-wills and several species of rare shrubland-associated moths. Knowledge of the presence and the locations of population concentrations of New England cottontails within Nantucket’s shrublands will enable better management of these ecologically important habitats.
Want to help? There is one additional way that New England and eastern cottontails can be differentiated: skull suture patterns. Skull sutures are junctions between the major bones of the skull. In New England cottontails, some of the skull suture lines are irregular and jagged, while those of eastern cottontails are smooth. If you happen to be a rabbit hunter and are interested in “donating” the intact head of any rabbits you harvest, the NCF Science and Stewardship Department will gladly accept your contributions – just store each specimen in an individual Ziploc bag (with the name and contact information of the collector, date, and specific location where the rabbit was harvested recorded with permanent marker on the outside) and freeze it while it is still fresh. Call the NCF’s office at 508-228-2884 and ask for any member of the science staff for more information!
*Please note, this blog post was originally published in The Inquirer and Mirror in the article series called Island Ecology. The Foundation’s Science staff regularly contribute to our local newspaper and reprint the articles here the following week.
The Nantucket Conservation Foundation is a private, non-profit land trust that depends contributions from our members to support our science projects, conservation property acquisitions and land management efforts. If you are not already a member, please join us! www.nantucketconservation.org