Long Island Mammal Survey

Long Island Mammal Survey

Filling a 60-year Data Gap

Have you ever seen a Gray Fox here on Long Island? How about a Long-tailed Weasel or a Mink? These three species are among several mammals whose status and distribution on Long Island are currently unknown. The last extensive mammal survey on the island was conducted from 1960 – 1963. Led by Paul Connor, a scientist with the New York State Museum and Science Service, it culminated in the 1971 publication, “The Mammals of Long Island, New York.”

Through generous funding from the Long Island Community Foundation, Seatuck launched a multi-year campaign to address this gap and map the distribution of some 27 terrestrial and semi-aquatic wild mammals thought to exist on the island.

The campaign will not only update Conner’s work on Long Island, but will also supplement the statewide New York Mammal Survey, the first-ever attempt at mapping distributions of all of New York’s more than 70 species of mammals, from mice to moose. With funding from the NYS Department of Environmental Conservation (DEC), a project team at SUNY College of Environmental Science and Forestry is compiling available mammal data from museums, literature, universities, state agencies, social media and other sources. The New York Natural Heritage Program is leading smaller efforts on State Parks and in the Adirondack and Catskills Forest Preserves.


There have been many dramatic changes in the composition of Long Island’s mammals over the last four centuries since colonial settlement. Quite early on, unregulated hunting and trapping during the Fur Trade era eliminated the Black Bear, Beaver and River Otter, while bounties wiped out the island’s population of Gray Wolves and Bobcats. A combination of habitat loss and habitat changes greatly diminished our population of Gray Fox, once the common fox species here, in favor of the Red Fox, and habitat changes favored the Eastern Cottontail over the now endangered New England Cottontail. It’s possible that both the Gray Fox and New England Cottontail are no longer found on the island. Our Striped Skunk population, “formerly common the length of the island” according to Connor, took a dramatic downturn in the early 1900s. This has been associated with the use of Paris green poison to control the Colorado potato beetle infestation around that time, the latter being a favored food item of the skunk.

On the other hand, several new mammals have settled on Long Island since the 1600s. Most of these have been introduced, some knowingly and other inadvertently, by humans. Among the former are Sitka Deer from eastern Asia introduced many years ago to a private game preserve on the Carmans River, Black-tailed Deer released at a private hunting preserve on Shelter Island (now known as TNC’s Mashomack Preserve), and several hare (Lepus) species released in various locations: Snowshoe Hare (L. americanus), European Hare (L. euroeaus), and Black-tailed Jackrabbit (L. califonicus).

Virginia Opossum (Didelphis virginiana)

Our only marsupial, the Opossum, arrived on Long Island sometime in the late 1800s. A southern species, it is not clear if this was a natural northerly range expansion, as is the case with some bird species such as the Northern Cardinal and insects including the Southern Pine Beetle. Two rodent species – the House Mouse and the Black Rat – arrived as stowaways by ship from the “Old World” with the early colonists. The Norway Rat, another ship stowaway from Europe that did not arrive until the mid-1700s, displaced its cousin the Black Rat. Today the House Mouse and Norway Rat are widespread throughout Long Island.

The Eastern Coyote is a very recent arrival, having arrived here on its own in 2009 and first bred on the island in 2016. Another recent addition to our mammalian fauna is the River Otter, returning to establish a breeding population sometime in the 1990s after a several hundred-year absence. And the distribution of several relatively common mammal species (e.g. Woodchuck, Southern Flying Squirrel and Eastern Chipmunk) has changed dramatically since the 1960s survey.

Why Survey?

The NYSDEC is charged with managing our native wildlife species throughout the state. Management plans are established for specific wildlife management units (WMUs) based on the species found there and their population status. Developing and implementing management plans requires knowledge of current species distribution, population trends and threats. In terms of mammals on Long Island, staff have undertaken population surveys to update information on the distribution and relative abundance of White-tailed Deer, River Otter and several bat species, but there has been no comprehensive survey work done and there is no baseline information on Long-tailed Weasel, Striped Skunk, Mink or Gray Fox. These are considered rare species by most wildlife biologists here, yet the current state regulations allow trapping for all four species on Long Island. Some wildlife biologists feel that current state regulations do not reflect the population status of these species in WMUs 1A (Nassau), 1C (Suffolk) and 2A (Brooklyn and Queens) and needs to be amended.

It is important to note that the geography of Long Island, with its closest point to the mainland being the New York City metropolis, poses a challenge for natural recolonization of extirpated terrestrial as well as some semi-aquatic mammals from robust mainland populations. Therefore, great care should be taken in managing these species to avoid local extirpations here.

Survey Methods

The Long Island Mammal Survey has two distinct components: 

  1. Using remote trail cameras to document and map the distribution of our medium-sized (squirrel) to large mammals (deer);

    2. Live trapping our smallest mammals (shrews, mice, moles, voles).

We will be enlisting the help of Long Island’s conservation organizations, school and scouting groups, and interested volunteers to monitor trails cams and download their images to the Long Island Mammal Survey iNaturalist site (https://www.inaturalist.org/projects/long-island-mammals).

The component involving live-trapping of small mammals requires a training workshop by SUNY – College of Environmental Science and Forestry or NYSDEC staff. A number of natural resource agency staff on Long Island went through the training in July 2022. Using those protocols, Region 1 DEC staff are planning to survey for small mammals at twenty sites on Long Island.

We will also be “mining” existing data bases (e.g. iNat, L.I. Wildlife Photography’s Facebook page, NYC Parks Wildlife Unit’s surveys, research on red foxes by VaTech on Fire Island) and contacting licensed nuisance trappers, pest control companies and wildlife rehabilitators for information. To encourage school groups to get involved in the project, and to educate Long Islanders about our wild mammals, a series of informational videos will be created. These will provide identification tips and well as interesting behavior and natural history aspects for each species.


Eastern Coyote (Canis latrans)
Flying Squirrel (Glaucomys volans)