Delmarva Fox Squirrel Continues to Do Well a Year After Endangered Species Act Delisting
Biologists are monitoring the species under a five-year post-delisting plan to ensure population remains stable
On a chilly early spring morning, in the remote swamps of the picturesque Blackwater National Wildlife Refuge, a team of biologists and volunteers are trekking through mud and water to gather data on a rare species found nowhere else but within the East Coast’s Delmarva Peninsula: the aptly named Delmarva Peninsula fox squirrel (Sciurus niger cinereus), or simply Delmarva fox squirrel. Fortunately, the scientists are collecting data not because the squirrels are in decline, but rather, for confirmation that the species continues to do well — December 2016 marked the first anniversary of the delisting of the fox squirrel from the Endangered Species Act after nearly fifty years on the list.
photo by Mark Hendricks
Joining the team for the day to document their efforts, I’m told that if we’re lucky, we may catch a glimpse of the notoriously furtive squirrel. “Sometimes they disappear into the woods so silently and at other times they are really brazen to hunters in tree stands,” says Cherry Keller, endangered species program leader with the US Fish and Wildlife Service Chesapeake Bay Field Office.
At first glance the squirrel appears much like the common grey squirrel that frequents backyards, college campuses, and other urban environments. Upon further inspection, however, you will find that it is rather large, about two and a half feet long, with a long, full tail that may make up to 15 inches of its total body length. Additionally, its body is adorned with a silvery gray, almost metallic looking fur, which is quite beautiful. “They are really gorgeous and they can be elegant at times and clumsy and comical at others,” adds Keller.
The squirrel was one of the original species placed on the Endangered Species Preservation Act in 1967 (the predecessor of the Endangered Species Act) because of habitat loss and overhunting. At the time of its listing, it only occupied 10 percent of its historic range, which at one time included parts of New Jersey and Pennsylvania and all of the Delmarva Peninsula, but had shrunk to only a few spots in rural eastern Maryland. The species spends much of its time on the ground and exists primarily in mature forests of mixed hardwood and loblolly pine. As these forests were harvested for agriculture and urban development, the squirrel’s population dropped dangerously low.
Because the majority of habitat deemed suitable for the squirrel existed on private land when it was listed in 1967, conservation efforts were successful in large part because both federal and state officials established partnerships with private landowners. Some landowners allowed squirrels to be successfully translocated onto their properties while others allowed their land to regrow into suitable habitat that the squirrels naturally expanded their range into. This partnership between government officials and private landowners was imperative to the species recovery and rightfully lauded.
“Without cooperation from private landowners the Delmarva Fox Squirrel would not have been removed from the Endangered Species Act,” says Glenn Therres, associate director with the Maryland Department of Natural Resources Wildlife and Heritage Service. “We could have saved it from extinction, but it would not have recovered.”
photo by Mark Hendricks
“This is a huge success story. The recovery and delisting of the species is the result of state and federal agencies and private landowners working together,” echoes Matt Whitbeck, supervisory wildlife biologist for the Chesapeake Marshlands National Wildlife Refuge Complex. “The willingness of private landowners to provide habitat for endangered species is a big part of why the species recovered.”
The delisting has been years in the making. A 2007 status review indicated that the squirrel was close to recovery. The next status review, completed in 2012, concluded that it was no longer at risk for extinction and could be delisted. At the time of delisting, the squirrel’s population was estimated to be around 20,000 individuals spread across 28 percent of the Delmarva Peninsula.
Today the squirrel is doing well, especially on the land that encompasses the Blackwater National Wildlife Refuge, where the species continues to be monitored on a post-delisting plan. This plan is essentially a safety mechanism in case the population begins to decline again and the squirrels needs further protections under the ESA. Any species removed from the ESA is required to be placed on a post-delisting monitoring plan for a period of at least five years.
Monitoring under the delisting plan, however, is slightly less involved than when the species was endangered. When it was listed under the ESA, biologists were required to trap and release animals to record biological data. Now biologists at the Blackwater refuge utilize trail cameras to assess population dynamics. Specially trained volunteers help with the monitoring as well. “It’s great,” says Whitbeck. “It allows volunteers to assist with the work but it also frees staff to work on other projects.”
photo by Mark Hendricks
The help is especially welcome given the large monitoring area. The refuge is made up of 29,000 acres of forest, marsh, and water. Between 18 and 20 trail cameras are set up in a large 8,000-acre area within the refuge. Corn is laid out to lure the squirrels to the trail cameras, which works quite well. Multiple cameras are deployed for twelve full days at a time before images are downloaded, but are visited every 3 to 4 days to check on equipment and to add more fresh bait if necessary. These cameras will be used continuously during the five-year post delisting monitoring plan. Data collected from these cameras provide information on the squirrel’s occupancy of the refuge. Together with similar post-delisting plans being implemented on other public and private lands, biologists are using the data to develop statistical probabilities on squirrel occupancy and population.
“When we place cameras to monitor [the squirrels], they don't always 'capture' a squirrel, even if they are present. So it is important to know what the probability of detecting a Delmarva fox squirrel is, given the species is present. Estimating the probability of detecting will allow us to model the likelihood that an area is truly not occupied,” Whitbeck says of the process.
Thus far, data continues to support that the Delmarva fox squirrel population is stable and, in some parts of the peninsula, growing. Some organizations, such as the Center for Biological Diversity, are concerned about future habitat loss due to rising sea levels. This is of real concern, particularly in the land in and around the Blackwater National Wildlife Refuge. Yet these squirrels continue to surprise and are expanding their range further inland. Furthermore there is still suitable unoccupied habitat on the peninsula. For a species found nowhere else, this comeback is remarkable.
“Sometimes we describe all things as in decline — it’s not true. Delmarva fox squirrels are doing great and many other species are as well,” says Keller.