Matt Whitbeck of the U.S. Fish and Wildlife Service explains the trapping process used to track the Delmarva fox squirrel population. (Algerina Perna/Baltimore Sun video)

Trapped in a steel cage barely big enough to hold her, the large squirrel was not happy, pawing at the bars and trying them with her teeth.

Matt Whitbeck and Cherry Keller of the U.S. Fish and Wildlife Service were glad to see her, though. The furry gray prisoner, released after being weighed and checked, offered yet another sign that the Delmarva Peninsula fox squirrel, once vanishingly rare, has come back.

This supersized, reputedly shy member of the squirrel family now is considered fully recovered, according to federal wildlife officials. Confident the animal is back to stay, they plan to take the first step soon to lift all legal protections for it, something that hasn't happened much since Congress passed the Endangered Species Act 40 years ago.

"We're pretty excited about it. It's huge," said Whitbeck, a wildlife biologist at Blackwater, as he prepared to make an annual spring check of the Delmarva fox squirrels in the sprawling refuge south of Cambridge in Dorchester County.

"It's a neat, unique citizen of the Eastern Shore — it's something to be proud of," said Keller, an endangered-species biologist in the service's Annapolis office. She's spent the past 15 years overseeing efforts to restore the squirrel, but still considers it something of an enigma.

From a distance it might be hard to tell the Delmarva fox squirrel from the nosy, noisy grey squirrel familiar to most urban and suburban dwellers. The Shore native can be nearly twice as large as its common relative, reaching 30 inches in length, with half of that tail. It's a bit slower, and quieter, too, biologists say. That lack of chatter is part of the reason why scientists say they can walk through a forest they know harbors the animals and often not spot any.

One of 10 subspecies of fox squirrels found around the country, this one lives in trees like other squirrels, but it's somewhat less acrobatic and spends a fair amount of time foraging on the ground. It seems to do best in mature forests of hardwood trees and loblolly pines, especially when they border farm fields planted in corn — all of which still are fairly abundant on the rural Eastern Shore.

But in the first half of the last century, everything seemed to be going against the squirrel. Clearing of forests for farming, timber harvests and hunting all conspired to decimate its numbers. By 1967, when federal officials first listed it as endangered, the squirrel could be found in just 10 percent of the places it once frequented. Blackwater, with more than 28,000 acres of marsh, woods and water, was home to most of the survivors.

Since then, state and federal wildlife officials have labored to rebuild the population, reintroducing the squirrels to wooded areas where they were known to have roamed at one time. Eleven of those 19 "translocations" took, including nine on Maryland's portion of the peninsula.

Many of the relocations were to privately owned forestland, recalled Glenn Therres, who directed recovery efforts for the Maryland Department of Natural Resources. Owners agreed to take anywhere from five to 42 squirrels, he said, and they were not prevented from harvesting their timber, though they were required to leave 15 percent to 25 percent of it untouched for the animals.

"In that way, the squirrel never became a true liability to landowners," Therres said.

While landowners often believe having an endangered species on their property will prevent them from doing anything, Therres said that's just not so. Still, he acknowledged it may no longer be possible in today's political climate to reach the informal "handshake" agreements that cleared the way for squirrel relocations decades ago.

"We could have prevented the fox squirrel from becoming extinct by sustaining it on Blackwater refuge and on state lands," he said, "but we could not have recovered it without private lands."

It helped that the timber industry on Delmarva has changed over time, federal and state biologists say. Where landowners once focused on raising trees for paper production, they now cultivate them for lumber, which means trees can grow larger before being harvested, providing more habitat for the fox squirrels.

Hunters also have shifted their sights from squirrels to deer. And bow hunters, who often spend hours perched on stands in trees waiting for their quarry, have provided biologists with additional sightings and accounts of squirrel behavior.

Even so, the recovery has taken time. Whitbeck called the squirrels "homebodies" unlikely to roam far, which has meant they've only gradually expanded their territory from where they were transplanted.

That stay-at-home tendency is part of the animal's enigma, Keller said. Individual squirrels have been tracked for miles, but many others seem content to stay put.

"That's the thing — are they this elusive silvery gray ghost in the woods?" she said, with a laugh. "Or are they this bumbling fool on the edge of the road?"

"They seem to fill both models well," Whitbeck agreed.

The two Delmarva fox squirrels caught in traps checked one recent morning were both repeat customers, as indicated by the microchips detected under their skin. One has been trapped every year since 2010, Whitbeck said, and the other has shown up every other year since 2007 — remarkable for an animal that normally lives four to five years.