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Flying Squirrels

I have always marvelled at flying squirrels and their unusual abilities and biology. There are two possible species that can be found in North Durham and the Kawarthas.

The Southern Flying Squirrel is restricted to patchy appearances throughout our area but thrives best along the north shore of Lake Erie and into the USA, whereas the Northern Flying Squirrel can commonly be found throughout our area.

Fun Faunal Facts:

Flying squirrels hide away in cavities in trees during the day, coming out to hunt nocturnally. Their large eyes facilitate seeing in low light conditions, as they search for food and predators.

To be successful, these squirrels need lots of tall trees growing close together, so they can glide between them. A flying squirrel can’t actually fly but it can glide for distances in excess of 75 meters. The longest known ‘flight’ of the Northern Flying Squirrel was approximately 100 meters! During a glide, they can make turns of up to 180 degrees.

The life expectancy of flying squirrels in the wild is about 4 years, due to the wide range of species that prey on them, but in captivity a decade long life is not uncommon.

New World flying squirrels glow fluorescent pink under ultraviolet light, possibly to help them see and communicate better in low light conditions. These squirrels use a wide variety of vocalizations, including sharp squeaking calls, soft chirps, chuckling noises, churring, whining and various musical whistles.

Inspired by these flying squirrels, humans have made special suits that imitate the squirrel’s ability to glide. They are used by base jumpers and skydivers, allowing them to slow their descent and perform different manoeuvre while flying.

I mentioned these squirrels can’t actually fly, but assuredly they can travel significant distances between trees. They have a unique body feature that permits this form of travel. Along each side of their body, a flap of skin (called a patagia) stretches between the forelimbs and hind limbs and acts as a parachute, allowing the squirrel to glide from perch to perch.

Gravity has to be factored in, as these ‘wings’ don’t provide any lift, so in essence the squirrel starts high on one tree then glides downward to the next, climbs that tree and then glides downward again and so on.

It’s flat tail acts as a rudder allowing it to turn and steer as it descends. Flying squirrels can turn by lowering one arm, while a specialized piece of cartilage, not found in other gliding mammals, extends from the wrist to support the patagia and help them steer. These animals are capable of making sharp turns to evade flying predators like owls.

The flying squirrel is a voracious hunter/gatherer, relying on foods as diverse as birds’ eggs and nestlings, fungi, nuts, buds, seeds, berries, insects, other invertebrates and sometimes carrion.

Habitat loss and feral and domestic cats take many squirrels, but a new threat has emerged. There’s been a dramatic decline in the fungi they eat due to the presence of Hemlock Woolly Adelgids, invasive insects that destroy the Hemlock stands where this preferred fungi flourishes.

While the Southern Flying Squirrel tends to breed twice a year, the Northern only produces one litter per year. This likely has more to do with the range of the two species and the limits of climate rather than physiological differences. The nest is generally located in mixed deciduous/coniferous forest tracts, inside a tree cavity, rock crevice or nest box and are constructed of leaves, mosses, tree bark and lichens. Females alone care for the young, which are born blind, hairless and helpless.

So how do you tell them apart? Well it’s kind of tough because they are very similar in appearance. In the hand, measurements can help (e.g. the Southern is less than 25 cm long) and the base of the hairs on the belly can be studied, they are white to the base on the Southern and grey at the base on the Northern. But assuredly it is tough to tell them apart in the field!

Geoff Carpentier is a published author, expedition guide and environmental consultant. Visit Geoff on-line at www.avocetnatureservices.com and on LinkedIn and Facebook.

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