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Translocations help Delmarva fox squirrel expand its range

  • By Kathy Reshetiloff on September 08, 2013
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The Delmarva fox squirrel, top, grows up to 30 inches from nose to tail. (Richard Webster courtesy of USFWS) The common gray squirrel, right, grows to only 16–20 inches. (Charisa Morris courtesy of USFWS)

The Delmarva Peninsula fox squirrel (Sciurus niger cinereus) is only found on the Delmarva Peninsula; the land between the Chesapeake Bay and Atlantic Ocean that includes Delaware, eastern Maryland and eastern Virginia. This large tree squirrel inhabits the mature forests of this agricultural landscape.

By 1967, the Delmarva fox squirrel, as it is more commonly called, inhabited only 10 percent of the peninsula and was placed on the very first endangered species list. Its distribution at that time was restricted to three counties with a small historic translocated population in a fourth county.

The squirrel’s decline in the mid-1900s was fueled by many factors. Forests were cleared for farms and development. Timber was harvested on short rotations to supply pulp for paper markets, which kept much of the forest in stands too young to provide habitat for this squirrel. The overhunting of Delmarva fox squirrels may have also played a role in its decline.

Recovery efforts focused on expanding the squirrel’s range through translocations, and today there are 11 new thriving translocated populations. In addition, new populations have been discovered.

The Delmarva fox squirrel can grow to 30 inches (half of that is the tail) and can weigh 1–3 pounds. The squirrel’s coat is typically a uniform silver-gray but can vary to almost black. The only other tree squirrel on the Delmarva Peninsula is the common gray squirrel (Sciurus carolinensis). The gray squirrel is smaller (16–20 inches), has a narrower tail, brownish gray fur and is often seen in backyard bird feeders and suburban settings. The Delmarva fox squirrel is not typically found in suburban settings and can also be identified by its wide head and short ears

Although the Delmarva fox squirrel is a tree squirrel, it spends a considerable amount of time on the ground foraging for food in wood lots, and will take food from farm fields as well. Less agile than the gray squirrel, the Delmarva ambles along the forest floor more than leaping from branch to branch. They are also quieter than the common gray squirrel.

Delmarva fox squirrels prefer mature forests of mixed hardwoods and pines, with a closed canopy and open understory. The large trees provide acorns and seeds for food, and cavities for den sites. Their home ranges vary considerably, but average about 40 acres. Individuals have been known to live at least seven years in the wild. In the spring, females have litters that range from one to six young (four is average) in tree cavities or, sometimes, in nests of leaves.

A major focus of the recovery effort has been to increase the squirrels’ population size and distribution by re-establishing populations within the historic range. Sixteen reintroductions were made in Maryland, Delaware, Virginia and Pennsylvania. Eleven of these have succeeded 15–20 years after their establishment with evidence of growth and expansion; a high success rate for an endangered species.

Delmarva fox squirrels have also been discovered in new areas. This increase is due to natural expansion and reintroductions. The Delmarva fox squirrel occurs in eight counties on Maryland’s Eastern Shore; Sussex County, DE; and in Chincoteague National Wildlife Refuge in Virginia’s Accomack County.

The presence of Delmarva fox squirrels in a wood lot is not erratic as they tend to be present for long periods of time. They also can tolerate small timber harvests fairly well if there is an adjacent mature forest nearby and can use forests with a wide variety of tree species, as long as the forest is mature.

Monitoring this quiet, reclusive animal is challenging. Trapping and marking live animals has been conducted for many years on several national wildlife refuges, providing information on the population dynamics of these animals. Cameras placed in the woods detect Delmarva fox squirrels faster and easier than trapping and is less stressful for the animal. Determining the presence or absence of Delmarva fox squirrels in wood lots over time allows for an understanding of their persistence on the landscape.

Finally, the total range of this squirrel is understood from mapping the sightings made by many observers across the landscape. This animal is often seen by deer hunters in tree stands, farmers working their fields and others who live and work on the landscape.

The Delmarva fox squirrel is now found in 10 counties across 28 percent of the Delmarva Peninsula, and the total population is estimated to be about 20,000 animals. A recent analysis of the squirrel’s status and potential threats found that it is quite resilient to losses that might occur from development, sea level rise or other threats. A proposal to remove the Delmarva fox squirrel from the list of threatened and endangered species would be the next step to recovery.

To see a Delmarva fox squirrel and learn about this unique peninsula resident, visit any of these national wildlife refuges: Blackwater (Dorchester County, MD); Chincoteague (Accomack County, VA); and Prime Hook (Sussex County, DE). Also be on the lookout in the woods and field edges throughout its range.

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About Kathy Reshetiloff

Kathryn Reshetiloff is with the U.S. Fish and Wildlife Service’s Chesapeake Bay Field Office in Annapolis.

Read more articles by Kathy Reshetiloff

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