Delmarva Fox Squirrels

Delmarvalous

The Delmarva fox squirrel came back from the edge of extinction—and it’s still gaining ground

Lynne Warren
Animals
Mar 31, 2023

Whether eating (above left) or “splooting”—lying flat to cool off (above right)—more than 300 Delmarva fox squirrels now thrive in Chincoteague National Wildlife Refuge, an early relocation site. (Left photo by Lori A. Cash Conservation Photography; right photo by Arend Trent/Shutterstock)

THEY'RE BIG AND THEY'RE BACK. Delmarva fox squirrels—DFS for short—are among the largest tree squirrels in North America. Twice the size of more common gray squirrels, they weigh as much as 3 pounds and stretch up to 30 inches in length, half of which is an extravagantly fluffy tail. Thicker, shorter necks and smaller, more-rounded ears also distinguish DFS from their familiar gray kin.

But that distinctive physique isn’t the most extraordinary thing about them. In 2015, Delmarva fox squirrels were removed from the federal list of endangered species, nearly 50 years after their initial designation. The reason for delisting? Recovery. An estimated 17,000 to 20,000 squirrels are again making homes among stands of mature trees across 28 percent of their range on the peninsula that gives them their name.

Delaware, Maryland and Virginia share the Delmarva Peninsula, a slab of coastal plain shaped roughly like an upside-down teardrop some 170 miles long north to south and 70 miles wide at its bulging middle, with the Chesapeake Bay on one side and the Atlantic Ocean on the other. Just across the bay from the peninsula, in Annapolis, Maryland, lies the U.S. Fish and Wildlife Service (FWS) Chesapeake Bay Ecological Services Field Office, home base for the DFS recovery team. Led by endangered species biologist Cherry Keller, the team works with wildlife specialists and public lands managers across the peninsula to keep close tabs on the squirrels as part of a decadelong conservation process formally called post-delisting monitoring. “Spoiler alert,” Keller says. “They’re doing great.”

It wasn’t always so. By the mid-20th century, the big squirrel that once scampered all over Delmarva—and even occupied outposts in neighboring New Jersey and Pennsylvania—had disappeared from 90 percent of its historic range. “They were probably overhunted, and lost the old-growth woodland habitats they depend on” to burgeoning agricultural and commercial timber development, says Delaware Department of Natural Resources and Environmental Control wildlife biologist Holly Niederriter. “It’s clear that human activities caused their demise. We have a moral obligation to restore them as best we can.”

An image of Daisy (squirrel) getting a collar.

After a careful health check, squirrels trapped in Maryland for translocation to protected areas in Delaware are fitted with radio collars (above), which biologists use to monitor them. To date, about 66 animals have been relocated to sites with large, older trees and open understory, which the squirrels need for foraging and spotting predators (below).

The “Class of ‘67”

Important recognition of both loss and need for restoration came in 1967, when the Delmarva fox squirrel was included in what conservationists wryly call “the Class of ’67"—the first federal listing of “species threatened with extinction,” created under precursor legislation to the current federal Endangered Species Act. The squirrels were among 78 “classmates,” including such wildlife icons as whooping cranes and grizzly bears. Some species listed that year, such as bald eagles, have made celebrated comebacks; others on that first list, including many Hawaiian native birds and the tiny Maryland darter fish, have tragically not fared as well.

But even when their extinction risk was highest, pockets of Delmarva fox squirrels survived in a few Maryland counties clustered along the western edge of the peninsula. Blackwater National Wildlife Refuge (NWR) in Dorchester County, for instance—established in 1933 to protect birds migrating along the Atlantic Flyway—was and remains a crucial DFS stronghold.

To rebuild the squirrels’ range, healthy adult males and females from the most stable remnant populations were trapped and resettled in DFS-friendly but unoccupied habitats. Some of the earliest translocations, from 1968 to 1971, moved a total of 30 squirrels to the Chincoteague NWR on the Atlantic side of the peninsula. That population has since grown more than tenfold, and the squirrels have branched out into woodlands of Assateague Island both south and north of the original translocation site. The recovery strategy has established a total of 11 new populations, which have continued to grow decades after the first animals were released in each location. “The success rate of Delmarva fox squirrel translocations has been very high,” says Keller.

An image of a Delmarva fox squirrel on a branch.

The squirrels haven’t just been passive beneficiaries of conservation aid, however—they’ve taken their future into their own paws, too. Though DFS aren’t typically long-distance wanderers, “they will move,” Keller says, traveling across wetlands, even swimming small streams and crossing frozen rivers to reach prime habitat. By 2005, scientists discovered that the squirrels had established eight new populations on their own, and by 2012, they’d colonized areas of forest that connected formerly separate subgroups.

In all, the species’ distribution grew by nearly 40 percent between 1990, when the squirrels occupied 103,311 acres of peninsula forest, and 2020, when researchers documented them in 142,458 woodland acres, according to the FWS’s first post-delisting monitoring report published that year. “Science has contributed documentation of the Delmarva fox squirrel’s comeback,” says Pennsylvania Western University wildlife biology professor Carol Bocetti, who has worked with the species recovery team for decades. “But translocations have been the key to making that recovery happen.” Translocations—and the right kind of trees.

“People all over Delmarva take pride in this animal, and in its recovery.” —Cherry Keller

An image of a Delmarva fox squirrel running.

“At times they can look clumsy and comical, galumphing along a field edge”, says biologist Cherry Keller, “then they just vanish silently into the forest.”

Big squirrels, big trees, big benefits

Bocetti has studied the impact of timber harvests and changing forest structure on Delmarva fox squirrel populations for some 27 years. “DFS need the open understory that develops in old-growth forests for predator vigilance,” she explains. They spend a lot of time on the ground, traveling from tree to tree across the forest floor rather than jumping from branch to branch as their smaller, lighter-gray squirrel cousins do, and they need to see threats approaching. Older, bigger trees also offer better nest sites and produce more food, with the squirrels often eating “while sitting on the ground with their butts up against a trunk for safety,” she says.

Changes in Delmarva’s forestry industry have helped bring back the mature woodlands where DFS can flourish. An early focus on producing pulpwood used for paper and related products—which calls for cutting trees on a 25-year rotation, when trunks may be just six inches in diameter and surrounded by scrubby sprouts and lots of undergrowth—decimated much DFS habitat. A shift to producing bigger trees suitable for milling into large pieces of high-quality lumber has benefited the squirrels by supporting the persistence of more mature tree stands—and each tree is worth more to the grower. “DFS can coexist with wise human use of the landscape,” Bocetti says. “There’s space for all of us if we just give each other a chance.”

The squirrels give back to the forest, too, promoting the growth of new trees and other plants by burying seeds, nuts and acorns as food caches. “In temperate regions, squirrels are our primary forest canopy mammals,” Niederriter says. “Delmarva fox squirrels occupy an important niche, and things in this ecosystem could look very different if we didn’t have these squirrels.”

Maryland-based writer Lynne Warren says, “Squirrels in old oak forests feature in some of my earliest wildlife memories.”