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Delmarva fox squirrel

The Delmarva fox squirrel (Sciurus niger cinereusis) is a large, heavy-bodied tree squirrel with an unusually full, fluffy tail [1]. Historically, it occurred in southeastern Pennsylvania, Delaware, south-central New Jersey, eastern Maryland, and the Virginia portion of the Delmarva Peninsula [2]. Because the Delmarva fox squirrels’ habitat requirements are somewhat specific (they require mature park-like forests) it is likely that populations were scattered and discontinuous. As forests were logged or converted to farms, they became unsuitable for the fox squirrel. As forests regrew, they were cut again before the mature forest required by fox squirrels could develop. By the turn of the century, the Delmarva fox squirrel had disappeared from New Jersey, Pennsylvania and Virginia and by 1936, it disappeared from Delaware as well. At the time of its listing as endangered in 1967, the Delmarva fox squirrel occurred on only about 10% of its former range in four eastern Maryland counties (Kent, Queen Anne’s, Talbot and Dorchester) [1].

After listing, population monitoring was conducted at remaining fox squirrel populations between the mid 1970s and the mid 1980s [2]. Populations were found to be healthy and to be naturally expanding their range [2]. Starting in 1968, efforts were made to translocate fox squirrels into unoccupied habitat. Delmarva fox squirrels were translocated and introduced at 17 sites within their historical range [1]. Eleven of the 17 translocations are thought to have been successful [1]. Between 1979 and 1991, squirrels were translocated into six counties in Maryland [1]. During the 1980s, Delmarva fox squirrels were translocated to locations in Delaware, Pennsylvania and Virginia [1]. Thus, the range contraction of this species has subsided [3] and the Delmarva fox squirrel can now be found in all counties on the Eastern Shore of Maryland and at a few sites in Delaware, Pennsylvania and Virginia [4]. More than 90% of the Delmarva fox squirrel populations known at the time of listing have persisted [3] and in the four Maryland counties where natural populations remained at the time of listing, Delmarva fox squirrels are more abundant and widespread [5]. Fox squirrels have also expanded naturally into one additional county in Maryland and one in Delaware [5]

In 1990, seven benchmark sites were selected at established sites to monitor Delmarva fox squirrel population status [1]. Six of these sites were in Maryland within the Delmarva fox squirrels’ remaining natural range and one was in Virginia on the Chincoteague National Wildlife Refuge [1]. Thirty squirrels were translocated to the Chincoteague National Wildlife Refuge between 1968 and 1971 [1]. This population reached a high of 300-350 squirrels in the 1990s [3]. In general, benchmark populations appear to be stable [5], although some sites experienced a drop in abundance after an outbreak of southern pine beetles in 1994-95 resulted in a loss of habitat [6]. The monitoring of benchmark populations was discontinued in 2000 [5].

Current threats to the Delmarva fox squirrel include development, timber harvest, short-rotation pine forestry and forest conversion to agriculture [1]. Because much of the squirrel’s occupied habitat is on privately owned lands, the success of conservation efforts will be largely dependent on management practices on these lands [7]. By 2001, 114 conservation easements had been established totaling 23,019 acres in the three counties that support the majority of Delmarva fox squirrels [5].

[1] U.S. Fish and Wildlife Service. 1993. Delmarva Fox Squirrel (Sciurus niger cinereus) Recovery Plan, Second Revision. Hadley, Massachusetts. 104 pp.
[2] U.S. Fish and Wildlife Service. 1984: Proposed Determination of Experimental Population Status for Introduced Population of Delmarva Fox Squirrel; Federal Register (49:13556-13558).
[3] Therres, G.D. and G.W. Willey, Sr. 2005. Final Report to USFWS: Persistence of local Delmarva fox squirrel populations between 1971 and 2001. Maryland Department of Natural Resources, Annapolis, MD.
[4] U.S. Fish and Wildlife Service. 1999. The Delmarva Peninsula fox squirrel. U.S. Fish and Wildlife Service, April 1999. Website (http://training.fws.gov/library/Pubs/foxsquirrel.pdf ) accessed October, 2005.
[5] Therres, G.D. In press. Conservation of the Endangered Delmarva Fox Squirrel: State and Federal Recovery Efforts. In The Endangered Species Act and Federalism: A path to stronger federal and state collaboration for species conservation.
[6] Dueser, R.D. 1999. Project Report to USFWS: Analysis of Delmarva fox squirrel (Sciurus niger cinereus) benchmark population data (1991-1998). Dept. of Fisheries and Wildlife, Utah State University, Logan UT.
[7] Ratnaswamy, M.J., C.E. Keller, G.D. Therres. 2001. Private Lands and the Endangered Species: Lessons from the Delmarva Fox Squirrel in the Chesapeake Bay Watershed. Transactions of the 66th North American Wildlife and Natural Resources Conference.

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