15 Feb Northern flying squirrel Glaucomys sabrinus
Regardless of which species we are talking about, flying squirrels are impressive for their means of locomotion.
The diminutive northern flying squirrel is a small species of squirrel native to North America. It is one of three ‘new world’ flying squirrels that occur on that continent, the others being the southern flying squirrel (Glaucomys volans), and a brand new species – Humboldt’s flying squirrel (Glaucomys oregonensis) – that was shown to be different from the other two by genetic analysis in May last year. And therein lies the problem with this month’s “specimen of the month” – although the UNE Natural History Museum is a new museum, we have a lot of old specimens collected and donated long ago, and some of these arrived in our collection a little short of information. If our specimen was collected in western North America – California though to British Columbia – then our specimen is Humboldt’s flying squirrel, but if collected anywhere to the east of that, we have the more widespread northern flying squirrel. We are currently scouring import permits and old hand-written notes in our archives to solve this problem.
Regardless of which species we are talking about, flying squirrels are impressive for their means of locomotion, and for their diet too. I studied northern flying squirrels as a postdoctoral fellow in New Brunswick (Canada) in the early 2000s, researching their dietary and spatial ecology. What I found was that these animals – although they don’t technically ‘fly’ – are impressive gliders, travelling up to 100 metres through the air from the canopy of one tree, to the base of another during their nightly movements around their home range. They do this by extending their gliding membrane (called the ‘patagium’) between their fore and hind feet as they leap from a tree. They can change direction in flight to avoid obstacles too, and finish each aeronautical adventure by going into a stall and alighting gently on the target tree trunk. And all of this is accomplished in the dark of night. I found that they preferred to land on rough-barked trees to give them better grip, while other researchers have noticed that as soon as they land they immediately scurry to the far side of the tree, in case they were being pursued in flight by a predatory owl.
Their diet is equally interesting. Northern flying squirrels eat truffles (underground fungi), which they dig up from beneath the leaf litter. This might seem incongruent with their gliding style of locomotion – after all, truffles are underground, and the squirrels are gliding high above – but the two actually go hand in hand. Truffles are patchily distributed in forests, and there can be large distances between fruiting clusters, so gliding is an efficient way to traverse those cold spots in the landscape. But because they have a keen sense of smell, flying squirrels can smell ripe truffles ‘on the wing’ so to speak, and change direction to land right on top of the food source. Because they spread the spores of these beneficial fungi throughout the forest via their scats (faeces), northern flying squirrels are really important for the health of the forest ecosystem in North America. But, because they are tiny (about 100 grams), silent, and entirely nocturnal, most people never see them, or know of the existence of this amazing little mammal.
– Written by Associate Professor Karl Vernes
Mammal Ecology and Conservation