Patterson - Flying Squirrels

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					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,, 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
United States.

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

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.

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