What are Southern Flying Squirrels? 

Southern Flying Squirrels (Glaucomys volans) are small omnivorous mammals, and one of 8 species of squirrels in the Great Lakes Region. The other seven species are Northern Flying Squirrels (Glaucomys sabrinus), Eastern Grey Squirrels (Sciurus carolinensis), American Red Squirrel (Tamiasciurus hudsonicus), Eastern Chipmunk (Tamias striatus), our largest species, the Woodchuck (Marmota monax), Eastern Chipmunk (Tamias striatus), Least Chipmunk (Neotamias minimus), the smallest species, found throughout the boreal forest, and the Fox Squirrel (Sciurus niger), observed solely on Pelee Island in Canada. All species of squirrels are rodents (order Rodentia).  

In the Long Point Basin and other areas close to Lake Erie, both species of native squirrel co-occur, though the Southern Flying Squirrel is much more common. As one travels north throughout the province, relative abundances shift. Within southwestern Ontario, the northern distribution limit of Southern Flying Squirrels is around 43°N latitude (Grand Bend to Hamilton), but eastward, Southern Flying Squirrels also occur in Simcoe County, the Kawartha Lakes, and in the Frontenac Region. In more northerly areas, such as the Saugeen-Bruce Peninsula, Manitoulin, Algonquin Park, and the Algoma District, populations are almost exclusively of the Northern Flying Squirrel species.  

Flying Squirrels are Ontario’s only squirrels which are primarily nocturnal, which makes them difficult to observe. Additionally, the two native species of Flying Squirrels have very similar fur colour and patterns, making them difficult to distinguish. Side by side, the Northern Flying Squirrels is significantly larger than the Southern Flying Squirrel (25-35 cm for the Northern Flying Squirrel, in comparison to 20-25 cm for the Southern Flying Squirrel). Evolutionary biologists sometimes attribute the smaller size in Southern Flying Squirrels to the warmer climate – there are decreased metabolic costs with a small body size in warm climates compared to colder, more northerly climates. Unique predation and competitive pressures, as well as ecosystem structure may also select for a smaller body size in Southern Flying Squirrels. This follows a general ecological principle termed Bergmann’s Rule; where within taxonomic groups, body size of animals increases towards the poles, and decreases towards the equator.

Ecology of Southern Flying Squirrels   

In the summer, Flying squirrels feed on fruit, nuts, mushrooms, insects, and carrion. When autumn arrives, they shift their diet to primarily consume acorns, hickory nuts, beechnuts, which they cache for future consumption in the cold winter months. Predators of Southern Flying Squirrels include Red Foxes (Vulpes vulpes), weasels (Mustelidae), snakes (Squamata), owls (Strigiformes), hawks (Accipitriformes), and raccoons (Procyon lotur). Similarly to other members of the Squirrel family, the lifespan of Southern Flying Squirrels is short, between 4-6 years, with many individuals having shorter lifespans due to predation and competitive pressures. In the Long Point Basin, Southern Flying Squirrels are found within forested habitats – including upland mesophytic hardwood forests, deciduous swamps, and oak woodland-savannas.  

Sexual maturity is attained at the age of 1 year. Following this, both males and females breed twice a year – once in early spring, and again in midsummer. Gestation is around 40 days, and the young squirrels are provisioned for by their mother for 120 days, afterwards which they are fully independent. Nests are placed within natural tree cavities and woodpecker holes, though they also build leaf nests for roosting in the summer months. Their home range is up to 16 ha in size for adult males, and 8 ha for adult females.  

Southern Flying Squirrels are highly social animals, especially in the colder months outside the breeding season. Many squirrels can gather within a single cavity to conserve heat, increasing winter survival. Southern Flying Squirrels have also been observed foraging in large groups. They are tolerant of other individuals not in the immediate family group, which increases chances of outbreeding, improving genetic fitness.  

How do Flying Squirrels glide?  

Flying Squirrels are not capable of sustained flight in the same manner as birds and bats – their common name is a misnomer. Instead, their movement is a controlled descent. To glide, Flying Squirrels use a patagium – a furry membrane stretching from the front to rear legs. They typically glide downwards at an angle of 30-40 degrees, with the ability to make sharp tuns up to 180 degrees to avoid obstacles and predators. Gliding is metabolically advantageous – these squirrels save substantial quantities of energy compared to tree squirrels and chipmunks. Before landing on a tree, Flying Squirrels will reorient themselves upwards to reduce the impact of the landing – a function like that of a parachute. They also have cartilaginous projections from their wrists – allowing them to support their patagium and grasp trees securely. Flying Squirrels often immediately scurry to the opposite side to avoid predators when landing on trees after gliding.  

Observing Flying Squirrels  

Flying Squirrels are difficult to find – but it is always a rewarding experience observing these elusive rodents! To maximize your chances, you can: 

• Walking or hiking at dusk or dawn (or better yet, registering for a night hike) within mature deciduous forests.  
• Camping at one of the many parks or conservation areas that Ontario has to offer.  
• Late autumn and winter are the best times to view Flying Squirrels, considering a lack of foliage on deciduous trees obscuring wildlife 
• Monitoring your bird feeder throughout the nighttime hours. Flying Squirrels are just as attracted to bird feeders as Grey Squirrels and Chipmunks. 
  
• Under ultraviolet light, Southern Flying Squirrels will glow pink – thanks to fluorescence!

 

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Written by: Matthew Palarchio  – HBSc, Environmental Sciences, Western University

Photos: © Mary Gartshore, iStock, Lyn Roueche

 

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