flying squirrel

Editor’s note: The Courier Express, in collaboration with Lola M. Smith, MS, lecturer in biology at Penn State DuBois, is republishing a series of work this week completed by college students about endangered species in Pennsylvania. References for the work, similar to a college research paper, are credited at the end for each article.

The northern flying squirrel (Glaucomys sabrinus macrotis) is an endangered species in Pennsylvania that is not nationally listed as endangered with the US Fish and Wildlife Services. The northern flying squirrel is confirmed to be currently found in seven Pennsylvania counties, Warren, Potter, Wayne, Pike, Monroe, Carbon, and Luzerne. The preferred habitat of this species is a conifer heavy old-growth forest with moist soils. However, with the limited old-growth forest found in Pennsylvania they can be found in a mixed second-growth forest. (Butchkoski and Turner 2010) “This squirrel is about 8 1/2 to 10 1/2 inches in length, including a 3 1/2 to 5-inch tail. Its large eyes are adapted for night vision. The fur of the flying squirrel is very soft and tan-brown in color, with white underparts. The so-called flying membrane is a loose flap of skin between the fore and hind legs on either side of the body; this is stretched taut when the legs are extended, allowing the animal to soar or glide but not to fly in the true sense of the word.” (Fergus 2007)

There are a few factors leading to this species being considered endangered in Pennsylvania. One of the largest problems for this species and many other is the loss of suitable habitat. This is a large issue in the north-eastern part of their range in Pennsylvania. The loss of old-growth and second-growth conifer and mixed-wood forests lead to a decline in suitable nest trees. The hemlock wooly adelgid is also causing some concern for this species as it is leading a decline in older growth hemlocks, which is one of the northern flying squirrels preferred nesting trees. The next largest threat to this species is the smaller yet more abundant southern flying squirrel out competing the northern flying squirrel for suitable nesting trees. This is due to the northern flying squirrels range expanding further north, this appears to be related to the trend of warming climates. The southern flying squirrel also carries a lethal or debilitating parasite to the northern flying squirrel. (Butchkoski and Turner 2010)

As a recovery plan, the Pennsylvania Game Commission (PGC) started to do research on the northern flying squirrel in 2001. With the information received from the monitoring of these individuals as well as the nest boxes placed for this research, the PGC designated this species as state endangered in 2007. The continued plan is to determine the exact range of the species, as well as tracking the population and reproduction trends of this species. Along with monitoring of nest boxes statewide in areas of know populations and areas of potential population. The plan also recommends the consideration of preserving older growth hemlock and mixed hardwood forests within the species range as well as within a 5-mile radius of a known population. (Butchkoski and Turner 2010)

To help biologists to determine their range, forest landowners can place and monitor nest boxes and if they believe a northern flying squirrel takes up residence in their box, they can contact their local PGC regional office.

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Northern Flying Squirrel PGC Species Profile-Eileen Butchkoski and Greg Turner-Pennsylvania Game Commission


Wildlife Notes- Chuck Fergus-Pennsylvania Game Commission


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