Mammals: Flying Squirrel

Blustery wind gusts toppled snow from evergreen boughs, as the snow tracking class group meandered along the trail. They came across a fresh set of moose tracks, and humorously called them bullwinkle’s trail. As the switchback leveled out, they spotted a unique imprint in the snow at the edge of the path. It took a few seconds to process, but the obvious caped landing of a flying squirrel was evident. And now, the they were on the rocky and bullwinkle trail!

The cape of the Northern Flying Squirrel (Glaucomys sabrinus) is actually an expandable furred appendage of skin on both sides of this species body that outstretch from its neck all the way down to its feet called the patagia. This miraculous adaptation of nature has muscular chords interlacing the patagia, which allow this stealth jet pilot of the forest to do a series of amazing things. This flying squirrel can not only glide, but they can change the shape of this cape from folded to angled, to fully extended, to inflated. These acrobats of the air can glide 50-to-300 feet, and make vertical leaps and dives, changing trajectory in mid air to avoid predators. They soar into tree cover, and simultaneously inflate their cape like a parachute and adjust their flattened tail to land vertically into the tree bark. This is a stunning spectacle to witness these aerodynamically talented species in action.    

The northern flying squirrels have thick, light brown to cinnamon fur on the upper body, gray flanks and whitish underparts. The total length including tail is about 12 inches. They have extremely large eyes designed for nocturnal vision, striped heads, long whiskers, and weigh about 6 ounces. In Kootenai Country Montana, they generally prefer mature to old growth evergreen forests, but will utilize sub-alpine zones or cottonwood stringers near water bodies. Diet consists of pine nuts and seeds, mushrooms, tree sap, insects, bird eggs, nestlings, young snowshoe hares, carrion, aboreal lichens, and are believed to be able to locate underground truffles by sense of smell. Flying squirrels are a keystone species as they aid the intricate cycle of life in the forest by spreading fungal spores as they forage    

The Northern Flying Squirrel will nest in natural cavities, abandoned woodpecker holes, or in the thick stunted branches of mistletoe infected larch or fir trees. They will occasionally nest underground. These acrobats usually mate in winter-spring, and may at times have a second litter per year. Females can have multiple male suitors performing aerial display flights.    

Predators include great horned owls, great gray owls, screech owls, goshawks, red-tailed hawks, Canadian lynx, American marten, red fox, and bobcats. Leftover tails of flying squirrels indicate a kill site where owls have taken this species. Tracks are small and somewhat blurry due to furry paws, front feet tracks 1-inch long, rear are 1.5-inches long. When bounding, rear feet show ahead of front. This species usually climb down trees rather than glide. However, trails may originate far from trees, where an animal glided and landed. These landing spots are called sitzmarks, can be as long as two feet, and are another special treat to find in Kootenai Country Montana!    

(Author’s Note: Reference - Montana Outdoors 2012, A. Balyaev.)