Officials aren’t sure exactly how many northern flying squirrels remain in Pennsylvania, but they do know there aren’t many.
And they’re also concerned that in the near future, there could be none.
The diminutive creature is one of two flying squirrels in the state. The southern flying squirrel, which is smaller, has been expanding its range northward and creating a multitude of problems for the northern species.
Greg Turner, an endangered species biologist with the Pennsylvania Game Commission, said the northern flying squirrel has been found in only three locations -- the Poconos, and Potter and Warren counties. Although he isn’t sure exactly how many remain, Turner said that, since 2001, only 38 have been captured out over more than 700 nest boxes that biologists use to live trap the squirrels.
Still, Turner said more data needs to be collected before a thorough population analysis can be performed. For now, he can only base his conclusions on the current surveys of nest boxes, which is giving a glimpse at the severity of the situation.
“When you look at the survey effort that it took to capture an individual in Pennsylvania and compare it to other states where they survey, such as West Virginia, our effort to capture an animal is five to 10 times greater than the work it takes to capture one in West Virginia,” Turner said. “That indicates our populations are lower.”
Turner added that the northern species, which prefers older growth forests with a heavy coniferous component such as red spruce or hemlock, used to be found across the entire northern tier of the state.
“Now, despite increased survey effort, we’re finding them at only a few sites,” he said. “That suggests they’re pretty rare.”
The reasons for the decline are many.
Turner points to habitat loss as a main contributor. As forests become more managed, northern flying squirrel densities have become lower, he said. The changes in the forest have reduced the amount of natural cavities and the mycorrhizal fungi that is their main food source.
That loss of old growth coniferous habitat - from timber practices or disease such as wooly adelgid, has led to another problem - the expansion of the southern flying squirrel. Turner said the species out-competes its northern counterpart for habitat and carries a roundworm parasite that is deadly.
“I’ve noticed through research I’ve done that this parasite is found in every southern and a good number of northern flying squirrels here, but where there aren’t any of the southern species, the northerns in those areas don’t have the parasite,” Turner said.
Dr. Mike Steele, who is a biology professor at Wilkes University, has conducted extensive research on flying squirrels and said the expansion of the southern species is creating yet another dilemma for the endangered northerns.
In areas where the southern and northern species overlap, Steele said genetic testing conducted in Ontario and Pennsylvania indicated that the two species are hybridizing.
“The loss of red spruce and the hemlock to wooly adelgid has brought the southerns and northerns in closer contact,” Steele said. “It’s an indication of how the environment is changing in Pennsylvania.”
And it’s a reason why Steele is alarmed at the fact that around three dozen northern flying squirrels have been found in Pennsylvania over the last 15 years.
So what can be done?
Turner said the PGC is trying to increase red spruce in areas inhabited by the northern flying squirrel and expand the coniferous growth to provide more habitat and increase the amount of fungi in the forest.
Steele said more funding is needed to conduct additional research to find existing populations and protect them.
In 2011 Steele published a book, “Terrestrial Vertebrates of Pennsylvania: A Complete Guide to Species of Conservation Concern” that includes 133 species in the state that are at risk.
He said when it comes to severity, the northern flying squirrel is in the top three among mammals.
“The northern flying squirrel is a state endangered species and it was always restricted to certain habitats,” Steele said. “But now it’s declining to the point where we’re close to losing it in the state.”