A flying squirrel munches on seeds that have fallen from a bird feeder in Dedham. Credit: Courtesy of Aislinn Sarnacki

The bird feeder saga continues, and this time with a boom in the dark of night.

“What was that?” I asked my husband as I sat up straighter on the couch, my eyes scanning the living room.

He pointed to a furry blob on a nearby window screen. The glow of the television paired with the darkness outside obscured the details of the creature, but we knew from experience, it was a flying squirrel.

As I hurried to unlock my phone to take a photo, the squirrel scurried off the screen and around a corner of the house, then plopped down onto our second-story deck. It was there for the bird feeder or, more specifically, the seeds and nuts that had fallen onto the deck below it.

I flipped on the deck light to find the tiny animal squatting, as content as could be, holding a seed up to its mouth with two tiny paws. Its big, dark eyes glistened. The white skin flaps under its arms rippled along its sides, a wave of velvety fur.

Maine is home to two different species of flying squirrels: the northern flying squirrel, which is native to the state, and the slightly smaller southern flying squirrel, which has expanded its territory northward in recent history. Both are similar in appearance, with the southern having a brighter, whiter belly than the northern. In the gloom of the porch, I wasn’t sure which species we were entertaining as a guest.

Both species are fairly small, as squirrels go, about the size of a chipmunk. And they often go unnoticed by people because they’re primarily active at night.

It was the second experience we’d had with our flying squirrels.

Years ago, a flying squirrel woke me in the middle of the night by landing on the window beside our bed. You know how a window screen booms when something strikes it? It’s an alarming sound when you’re fast asleep.

The squirrel then dropped down onto our tiny balcony, where I fill a bird feeder during the summer so I can watch birds from bed in the morning. (By now, our house is sounding rather grand with its decks and balconies, but I assure you that it’s a modest house with an interesting, outdoor-friendly design).

I remember my excitement at discovering that our forest was home to flying squirrels. I watched through the glass door of the balcony as it gobbled up seeds, seemingly undisturbed by my presence.

Years later, I wonder if our winter flying squirrel visitor is an offspring of that “original” squirrel, or perhaps a grandchild — grandkit?

I was eager to capture a clear photo, which is a challenge when photographing an animal at night through a window. Testing my luck, I slowly opened the door to the deck and crept out into the December evening’s biting cold.

The squirrel retreated into the shadows. I sat on the wooden deck boards, perched my camera on my knees and waited.

It only took a couple of minutes for the squirrel to resume its circuit around the deck in search of dropped nuts, seeds and dried fruit. Flying squirrels enjoy a varied diet in the wild. In addition to seeds and nuts, they forage lichen, mushrooms and sap. They even eat insects and bird eggs on occasion.

Some people have expressed disbelief when I tell them about the flying squirrels around my house. They either didn’t know that flying squirrels lived in Maine, or they assumed that flying squirrels were rare. But the animal isn’t listed as endangered or even threatened at the state level. According to the Maine Department of Inland Fisheries and Wildlife, they’re found statewide.

I started to think about what my little patch of forest might provide flying squirrels in terms of habitat. I hypothesized that the beech trees that surround my house might offer the squirrels both food and shelter. First of all, flying squirrels love beech nuts. Secondly, they nest in tree cavities.

As is the case throughout much of Maine, the beech trees around my house are diseased. I can tell because the trees’ typically smooth bark is covered in cankers. This bark disease causes the trees to eventually die and topple over, but this can take years. In the meantime, natural cavities form in the trees. In addition, woodpeckers drill holes into the trunks to find insects, forming cavities.

In the spring and summer, flying squirrels raise their young in tree cavities, which they line with shredded strips of bark, moss and lichens. And in the winter, they gather together in social groups called “huddles” to keep warm.

Other cavity dwellers live around my house. In fact, my most common winter bird feeder visitors — the black-capped chickadee, tufted titmouse, white-breasted nuthatch, hairy woodpecker — all nest in tree cavities.

My property’s abundance of mushrooms may also make it an appealing place for flying squirrels to live. I’m continually amazed at the variety of fungi I find in the woods, from tiny black trumpets to giant artist’s conks.

It’s possible that the flying squirrels are actually helping to create this mushroom-filled wonderland. A 2007 article in the Journal of Mammalogy details how flying squirrels eat truffle mushrooms, then poop out the spores, inoculating young trees and spreading the fungi.

Now that I’m almost done with my story, I realize that I’ve forgotten to answer the most obvious question: Do flying squirrels really fly?

It’s more of a “glide.” Skin flaps called patagia extend between the squirrels’ wrists and ankles. These wing-like features function much like a hang glider, catching the air so the squirrel can glide great distances. The squirrel’s somewhat flat tail is used as a rudder, helping it steer.

In the forests of southern New Brunswick, researcher Karl Vernes measured 100 glides made by northern flying squirrels in 1999 and 2000. The horizontal distance of the glides ranged from 10 to 148 feet, with males tending to glide greater distances than females.

Considering that, it’s no surprise that one showed up on my second-story window. It’s just a short glide from the nearest tree.

Since then, we’ve moved the bird feeders to a cluster of nearby trees (complete with a nifty pulley system to hoist them high). We were concerned about the amount of bird and squirrel poop being left on the deck. And so the saga continues.

Aislinn Sarnacki

Aislinn Sarnacki is a Maine outdoors writer and the author of three Maine hiking guidebooks including “Family Friendly Hikes in Maine.” Find her on Twitter and Facebook @1minhikegirl. You can also...