Ever heard strange, scampering noises coming from your attic in the middle of the night?

Most of us are quick to associate these sounds with a mouse or rat. To remedy my problem, I placed live mouse traps and glue traps throughout my house and attic. But my traps bore no results.

While working on my computer one night, I was startled to hear a scurrying noise from behind my computer desk. Once again, my original thought was a large mouse or small rat had gotten inside.

After seeing the two eyes staring back at me, however, I realized this was not the case.

I opened my front door and eventually coaxed the critter outside, taking a picture. Remarkably, it then took flight. After comparing the photo I took with photos online, I found it to be the endangered northern flying squirrel, one of Pennsylvania's rarest and unusual animals.

The northern flying squirrel (Glaucomys sabrinus macrotis) is one of only two species of flying squirrels found in North America. The other species is the somewhat smaller southern flying squirrel, found mainly in the southern United States.

Unlike most members of the squirrel family, both species are strictly nocturnal, meaning they only like to move at night. Their large eyes are an adaptation for nocturnal activity.

In Pennsylvania, the northern flying squirrel is considered an endangered species and is protected under the Game and Wildlife Code and under national law.

According the Pennsylvania Game Commission's (PGC) website, the rare northern flying squirrel is limited to northern conifer forests, while the smaller southern flying squirrel is more widespread. Despite very specific habitat preferences, the northern flying squirrel was once found across Pennsylvania's northern tier. The website also states that a Pennsylvania study conducted from 2003 through 2007 found only 33 northerns, which were all fitted with radio transmitters.

Flying squirrels, which have a home range of up to about 40,000 square meters for females, 50 percent higher for males, have skin flaps, called patagia, that extend between the wrists and ankles, and a tail that is flattened top to bottom so they can steer when jumping between high places. The northern flying squirrel, which has an overall body length of about 11 inches, travels principally by gliding from high points, while using its tail to steer.

It is known that northern flying squirrels enjoy acorns, beechnuts, fungi, lichens and conifer seeds, although food-hoarding behavior has not been documented in northern flying squirrels. Active year-round and primarily during evening and late night hours, the northern flying squirrel may only emerge briefly during the day. During severe cold, they forage mainly in the treetops and may cluster together to keep warm.

Information regarding reproduction of northern flying squirrels is limited, but available data suggests that in Pennsylvania, one litter is produced in mid to late May, ranging in number from one to four. At about three months, young northern flying squirrels take their first "test flights".

According to the PGC website, Pennsylvania's forests do not provide the old-growth conifer stands that provide better habitat for northern flying squirrels. Many remaining old-growth and appropriate hemlock/spruce habitat exists only in small, isolated fragments. As a result, our northern flying squirrels use forests that contain a diversity of coniferous and deciduous trees.

Habitat factors are influencing the northern flying squirrel's decline in Pennsylvania, such as the loss of older conifer and mixed forests to development, especially in the Pocono Region. Northern flying squirrels rely on specific fungi that are dependent on hemlock and spruce trees.

Although they are physically smaller in size, the more numerous southern flying squirrel appears to be a more aggressive competitor for tree cavities as well as food resources. Researchers stressed that it might also carry a parasite that may be debilitating or lethal to the northern flying squirrel. Studies in Michigan and Ontario, Canada, found evidence that the southern flying squirrel's range is growing northward while the northern species' range is getting smaller.

Despite its decline in Pennsylvania, the northern flying squirrel subspecies is still a common inhabitant of boreal forests of the Pacific coastal and Rocky Mountain states, states bordering the Great Lakes, and throughout Canada. It is considered rare, but can be found in small isolated pockets of suitable habitat along the Appalachian Mountains from Pennsylvania to Tennessee.

Starting in 2001, the PGC Board of Commissioners approved a series of three federal State Wildlife Grant Programs that monitored squirrel nests to gather population and reproduction data.

According to FlyingSquirrels.com, flying squirrels are probably the oldest living line of modern squirrels, showing evidence of their relative's existence that goes back to the late Eocene period, between 38 and 55 million years ago. The site adds that tree squirrels made their first appearance on this earth about 30 million years ago, while ground squirrels came started to appear 28 million years ago.

The northern flying squirrel, having emigrated to North America roughly 12 million years ago, is a relative newcomer to North America. The northern flying squirrel is found in coniferous and mixed forests throughout the top portion of North America.

Due to the large decrease in numbers, the U.S. Fish and Wildlife Service put the flying squirrel back under protection on June 6, 2011.