Steve Patterson — Flying Squirrels latter, Glaucomys sabrinus, is not. thereby giving it access to plentiful and
Southern flying squirrels have been in diverse food supplies.
Recap by Michael Frind North America for 25 million years; the
northern species has been here for 12 A flying squirrel’s diet is primarily
Steve Patterson, a seasoned naturalist and million years. An adult southern flying vegetarian, but animal-based foods are
long-time devotee of flying squirrels, gave squirrel weighs 122 grams, therefore less occasionally included as well. Nuts,
a superb presentation on these intriguing than a chipmunk. The southern species is chiefly those from oak (acorns), beech,
rodents. Accompanying his talk was not roughly 50% smaller than the northern hickory, walnut, and chestnut are
only a wonderful set of slides and video one, but is actually more aggressive. perennial favourites, as are maple
footage clips, but a real, live northern samaras. (Mast years, during which such
flying squirrel, which resided inside his Flying squirrels are distinguished by their comestibles are plentiful, result in the
shirt and was very willing to demonstrate ability to cover substantial distances by rodents increasing their numbers.) Other
its aerobatic abilities. traveling from tree to tree, directly squirrel delicacies include sundry berries,
through the air. Strictly speaking, these fruits, seeds, flowers, buds, bark, and
Steve’s interest in flying squirrels was rodents do not fly; rather, they glide. (The mushrooms (including truffles, which
first piqued when he observed white squirrel cannot gain lift nor can it propel they can find 6 inches below ground).
objects flying by him, whenever he was itself through the air once airborne, as a Squirrels sometimes eat carrion, insects,
relaxing on the porch of his cottage at bird or bat would do by flapping its wings, avian eggs, shrews, voles, mice, and any
night. Today, his non-profit educational or as an aircraft would do via an engine.) nestlings applicable to the foregoing.
organization, Glaucomys.org, is involved Typically, a flying squirrel begins its Their rodent teeth, with incisors hard on
in extensive, long-term hands-on research travels by climbing as high as possible in the front and soft on the backside, require
into flying squirrels. a tree. It looks for a suitable landing site, continuous gnawing in order to remain
and judges distance by moving its head sharp and of correct length.
Flying squirrels are typically members of horizontally and vertically. (Thus it uses
the Glaucomys family, a name which hints triangulation to perceive depth, as Flying squirrels are a mealtime favourite
at their oversized eyes. These huge eyes, predator-type animals with two frontally of owls of all types. Although the
analogous to those of an owl or to a mounted eyes do on a continual basis.) squirrels try to be as invisible and
premium-quality large-aperture camera Then it jumps off (its powerful hind legs inaudible as possible, owls are equipped
lens, enable them to be completely are ideal for leaping), extends all four with superlative vision and hearing, along
nocturnal (albeit some are crepuscular as legs, thus stretching out its two patagiae with silent wings, exactly for this reason.
well). Like most prey animals, flying (one on each side), and glides. The (On rare occasions, flying squirrels can be
squirrels have one eye on each side of the patagiae serve as highly efficient airfoils. seen in the daytime, but such individuals
head; this provides near-360º vision, but are usually juveniles who have just been
at the expense of depth perception. Steering is accomplished not with the tail, evicted from the nest or predator-
but rather simply by lowering a leg as frightened adults.) The common screech
Flying squirrels are well-adapted from required. The squirrel can thus glide owl can easily ingest the southern flying
other standpoints as well. Extended- around branches and other obstacles, squirrel, but not the larger northern one.
length whiskers facilitate the duties of albeit it is not quite agile enough to escape Predators of flying squirrels are not
these darkness denizens. Their large ears avian predators. The flying squirrel’s tail limited to owls and other winged
enable them to hear many predators. is horizontally flattened, and therefore in predators. Foxes, snakes, raccoons,
Their undersides (both body and flying any case is more suited to serving as a opossums, coyotes, wolves, and weasels
membranes) are white; from above, they stabilizer than a rudder. The animal’s also dine on squirrels.
are brown. This helps make them less glide enables it to travel 3 metres
visible from above (important for owl horizontally for every 1 metre drop. This Except for females during the nesting
avoidance) and from below (important in means that the squirrel must land as its season, flying squirrels are not very
moonlight, if a predator is present below). trajectory takes it nearer to the ground, territorial. A half-dozen males can forage
Their smooth, silky, moderately-long fur and so it alights quite low on the trunk of in one area. Both males and females can
(moulted each autumn in order to reduce a tree at its destination. The animal range over many hectares. The squirrels
fleas) not only provides good insulation always lands upright, with hind feet therefore help the trees, by spreading
for the small body, but muffles every touching first. Glides can extend mycorrhizal spores in their feces.
movement as well. The northern species horizontally as far as 150 feet (roughly 50 (Mycorrhizae are fungi types, most
additionally has hairs on the fleshy pads metres), but are often shorter. notably basidiomycetes, which live
of its feet. symbiotically underground with tree
After having landed, the squirrel quickly roots. The fungi protect the tree roots
The southern flying squirrel (Glaucomys scurries to the opposite side of the tree (in against viruses and provide much-needed
volans) inhabits deciduous hardwood order to elude a potential predator), and carbohydrates in return.)
forests in southwestern Ontario, with then scampers to the top of the tree, ready
occasional incursions as far north as Parry to repeat the gliding process. In this way, Because of flight dynamics, flying
Sound and as far east as Nova Scotia. The it can quickly move through the forest, squirrels cannot put weight on for the
northern species seem to prefer coniferous without having to contend with predators winter. Therefore, they do not hibernate.
forests. The former is considered roaming the forest floor. The squirrel can They are active year-round, albeit
endangered in Ontario. By contrast, the cover large distances with this method, because they store ample food in their
nests, they rarely venture outside in as translucent folds of skin. Even at 14 insulation and ample food placed in the
winter. At extremely cold temperatures, days, the eyes are still closed and the tail trap beforehand ensure the comfort of the
the southern flying squirrel enters into a is rat-like. At three weeks, the ears open; animal while awaiting surveying.
“power-saver mode”, or torpor; the the eyes open at about one month. The
northern version seems to be somewhat young are introduced to solid food (i.e. Southern flying squirrels are endangered
active even below this temperature. The weaned) at about 6-8 weeks, and are soon largely because of habitat destruction.
squirrels also conserve body heat by venturing about and practicing their Large tracts of undisturbed mature
aggregating into tree cavities. A single gliding skills. The young usually reside hardwood forest are required in order for
nest, well-insulated and hidden deeply with their mother until the birth of the them to thrive and reproduce. In this
inside a secluded cavity, can harbour up to subsequent litter. sense, flying squirrels are very different
50 southern squirrels or 10 northern ones. from the common urban red and grey
After mating, the male disappears, leaving squirrels. (Note that the ubiquitous red
Steve’s nesting boxes are simple affairs the female to raise the young entirely on squirrels can leap up to 10 feet, and thus
built from scrap pieces of eastern white her own. (Males live as vagrants, and use are occasionally mistaken for flying
cedar (the natural aroma discourages fleas nesting boxes simply for sleeping. They squirrels. Flying squirrels are distinctive:
and other parasites). The height and make only rudimentary nests.) not only are they nocturnal, but their
direction of the entrance hole are of little glides are more than an order of
importance. Steve notes that wearing Females, in stark contrast to males, are magnitude longer.)
gloves while handling the wood (and later, very dedicated in their parenting duties.
the box) ensures that lumbering They will move the nest if they feel any Unfortunately, prime southern flying
porcupines will not chew on the wood in threat is present. An accumulation of squirrel habitat continues to disappear at
pursuit of salt. Entrance-hole width ectoparasites (fleas, lice and ticks) can an alarming rate, especially in urban-
should be 1.5 inches for northern flying also cause a female squirrel to move her sprawl-riddled southern Ontario. A few
squirrels, and 1.25 inches if it is to house entire nest. To ease such moves for the holdouts remain, including riparian
the southern species. Holes can be female, Steve always places a second fringes (e.g. the forests along the Grand
surrounded with sheet metal in order to nesting box within sight of the first. River) and the occasional large,
guard against enlargement. unfragmented forests in rural areas far
During the first year of a flying squirrel’s from cities. Rural hedgerows, if
Flying squirrels do not mate for life, and life, mortality is high. Also, if the mother populated by mature trees, can harbour
so females frequently have different mates is eaten while the little ones still require flying squirrels too.
each year. Southern flying squirrels can care, then the young die as well. In the
mate twice each year: late winter and wild, a flying squirrel typically lives for Logging, even if done selectively, can
early summer. Although females are four years, albeit in captivity, it can live also be harmful to flying squirrels.
capable of producing two litters annually, for 10-15 years. Flying squirrels reach Mature hardwood trees are not only an
conditions are usually such that only one sexual maturity at about one year. essential source of squirrel food, but they
is possible. The gestation period is 40 provide nesting cavities as well. Dead
days. A given litter usually consists of During times outside the nesting season, trees, routinely cut for firewood, often
four individuals, but it can be as large as Steve sometimes surveys his squirrels. happen to be replete with ideal nesting
seven. Northern flying squirrels are This includes measuring and weighing cavities. Furthermore, the best nut-
similar in these regards to their southern them. To obtain the squirrels, Steve first producing tree species also happen to be
counterparts, but they can only breed once hits a suitable tree with a standard favoured for firewood as well as for fine
each year (typically in late spring). aluminum baseball bat. The squirrel furniture and flooring.
might then merely poke its head out, after
Steve noted that female flying-squirrel which Steve readies a pole-mounted net As growth in Toronto and the
nests tend to be very sophisticated in arrangement. A second impact of the bat surrounding area continues to accelerate,
terms of thermal performance: thickly and against the tree trunk causes the squirrel to most of the remaining undeveloped farms
warmly padded with the finest of exit the hole, whereupon it jumps directly and forests are becoming mere
insulating materials. These attributes are into the net. Within seconds, the squirrel investments for land speculators. This
essential for raising the young. Steve is weighed, measured, and released. devastating trend almost guarantees that
prefers to keep an eye on reproductive the southern flying squirrel will soon
activity through the use of infrared Another squirrel-surveying method entails vanish from any remaining habitats
cameras and microphones hidden in the live-trapping the rodents in small sheet- within commuting distance of Toronto,
tops of selected nesting boxes. He notes metal live traps, suitably mounted on irrespective of even the most vigorous
that inspecting a nest must be done with platforms high in squirrel-favoured trees. conservation efforts.
great care, as touching a nestling would Mounting the traps high in the trees
leave a scent that will cause the mother to avoids capturing deer mice. Steve noted Presently, the southern flying squirrel can
abandon it. that sheet-metal traps are preferable to still be found in the area ranging from
wire-mesh types, given that the former Point Pelee to Pinery PP to Hamilton.
Flying squirrels are born with ears, mouth, keep the caught animal from being seen (The more northern populations,
and eyes sealed shut. Newborns weigh by and harassed by potential predators. including sporadic ones in the Parry
less than 7 grams each (about the mass of The sheet metal also keeps wind from Sound and Ottawa areas, are often
20 paperclips). The patagiae are present chilling the diminutive squirrel. Fluffy decimated by the cold.) Toronto was
originally home to both northern and
southern species, although these squirrels
have long since vanished from the area.
Both species can also be found in the
Steve noted that only a few years ago,
southern flying squirrels were common at
Kortright in Guelph. But the construction
of vast tracts of densely-packed housing
subdivisions on the area’s prime farmland,
and right up to the edges of a number of
adjoining premium-quality mature
hardwood forests, has changed all this.
Although the trees continue to stand, the
daily forest incursions of people and
domestic pets have taken a severe toll.
Free-roaming feral cats, in particular, hunt
southern flying squirrels (and also birds).
No more flying squirrels have been
observed in the area since.
Steve has been studying flying squirrels
full-time in Grey-Bruce Counties for the
past 12 years. He maintains a staggering
400 nesting boxes (with all locations
GPS-logged), travels extensively to speak
and raise awareness about flying squirrels,
and is also a long-standing member of the
Owen Sound Field Naturalists. Details
about the research he pursues can be
viewed at www.glaucomys.org.
Sincere thanks to Steve for providing us
with a comprehensive overview of
Ontario’s flying squirrels. Thanks also to
his eager little four-legged friend Sabrina,
who provided us with impressive live
demonstrations of the capabilities of these
often-overlooked arboreal creatures.