Flying Squirrels

Here’s an unusual photo by Dave Bonta:
Flying Squirrel by Dave Bonta
It’s unusual because Flying Squirrels are generally nocturnal… in fact they are the only nocturnal squirrel here in Western New York.

The ranges of two species of Flying Squirrel overlap  in the northeast USA.  The Northern Flying Squirrel (Glaucomus sabrinus) is slightly larger than the Southern Flying Squirrel (G. volans).  If you sandwich the Eastern Chipmunk between them, you have our 3 smallest squirrels in order of size with the Southern Flying Squirrel being the smallest.

Both species are omnivorous.  Both will build twig-leaf nests, though they prefer tree cavities.  Neither hibernates, and neither truly flies.  Glides are achieved through the aid of the patagium, a fold of skin that stretches from wrist to ankle and is supported by a bit of cartiledge that extends the skin slightly beyond the foot.  This skin essentially turns the squirrel into a kite that can glide great distances compared to its body size.  The average glide of a Northern Squirrel is 66 feet, and that of the Southern 20-30 feet.

Based on where Dave lives and the apparent size of the squirrel in his picture above, I would guess it is the southern species, though I can’t be sure.  Here’s one from Sue in northern Ontario that I would guess is the northern species:
Flying Squirrel by Sue Nature Photonutt

If we could tickle their bellies, we would find the hairs on the Southern to be all white, while those on the northern are darker at the base and light at the tips.

Flying Squirrel Range MapNorthern
Total Length
:  10-12  inches
Tail Length:  4-6 inches
Weight: 2.5-4.5 ounces
Average Lifespan:  3-4 years

Southern
Total Length
: 9-10 inches
Tail Length:  3-4.5 inches
Weight:  2-3 ounces
Average Lifespan:  5 years

That’s the end of my squirrel series… Hope you enjoyed it!  Should I give you a quiz now?

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Eastern Fox Squirrel

Fox Squirrels are really pretty and a little bigger than Gray Squirrels.  They also like deciduous trees, but prefer areas where there is more open space beneath them.

 Curiously, the Eastern Fox Squirrel (Sciurus niger) does not range much into Canada.  Kurta says that there is a small, introduced populuation on Pelee Island in Lake Erie, and another small population in southern Manitoba.

Eastern Fox Squirrel by LucyCat
Total Length
: 20-23  inches
Tail Length: 9-10 inches
Weight: 25-39 ounces
Average Lifespan:  1-2 years

Fox squirrels eat  the buds, flowers and fruits of maple, elm, willow and other trees, berries, grapes and cherries, and the occasional grub, caterpillar, egg, or young bird.

Like the Gray Squirrel, Fox Squirrels scatter hoard nuts in preparation for winter.  Whereas the Grays retrieve up to 85% of the stored nuts, Fox Squirrels are reported to retrieve 99% of their winter cache.

Eastern Gray Squirrel

While Red Squirrels prefer conifers, the Eastern Gray Squirrel (Sciurus carolinensis) prefers mature deciduous trees that produce a good food crop…  Hickory, walnut, maple or beech.  Being rather adaptable, Eastern Grays can be happy out in the woods, or in your backyard, provided these trees are abundant enough.

Eastern Gray Squirrel by Marg MakeUpAnID
Total Length
: 17-20  inches
Tail Length: 7-10 inches
Weight: 12-25 ounces
Average Lifespan:  2 years or less

Like chipmunks and red squirrels, Gray Squirrels cache food for winter.  Unlike the smaller squirrels, however, Grays bury nuts singly, scattered.  In addition to nuts, they will eat mushrooms, insects, seeds, buds, flowers, and fruits.

They rarely travel more than 300 yards from their nest tree which is preferably a 12-inch deep cavity in the trunk, especially for winter shelter and for raising babies.  If no cavities are available, a loose nest may be built on a sturdy branch from twigs still bearing leaves.

Black Squirrel by Tom LeBlanc

A totally black melanistic phase of the Eastern Gray Squirrel is not uncommon.  Though it is the same species, many folks refer to it as Black Squirrel.

Red Squirrels

While Red Squirrels (Tamiasciurus hudsonicus) can be found in purely deciduous woods, they prefer coniferous forests – or at least a hardwood forest with some conifers because their favorite food is seeds extracted from pine cones.  In fact, they have a curious habit of going to the same eating perch repeatedly to rip scale after scale from cones to get at the seeds.  If you ever see a pile of pinecone scales in the woods, you can bet Red Squirrels have been eating there.  Poke around in the pile and you will also find the “cores” of pinecones – stripped bare of all scales.  It reminds me of corn cobs after a summer picnic!

Red Squirrel by Tom LeBlanc
Total Length: 11-14  inches
Tail Length: 4-6 inches
Weight: 5-9 ounces
Average Lifespan:  2-3 years

Red Squirrel by ERuthK at bodysoulspirit on FlickrRed Squirrels also eats buds, seeds, fruits, and mushrooms.  They seem to have a sweet tooth, as they will bite through the bark of a maple tree in spring allowing the sap to run.  As it trickles down the tree, water evaporates from the sap leaving a sticky, sweet treat, which Red comes back for in a few days.  In addition to these plant sources, Red Squirrels also eat insects, birds, mice, voles, and young rabbits.

If you enter Red Squirrel territory, you are apt to be scolded with a loud continuous chick-chick-chick.  (I remember getting a serious scolding once while setting up my tent near an Eastern Hemlock tree…  Eventually he decided to allow my presence, but it was clear he didn’t like it!)

Red Squirrels prefer to nest in a tree cavity, but if none can be found, they will weave a basketball-sized nest in the branches of trees from leaves and twigs.  Occasionally, they will nest on or underground, especially in winter.

Two cool vocabulary words related to Red Squirrels:

  • Midden – the pile of “trash” (pinecone scales and cores) left behind from eating pinecone seeds.
  • Cache – the pile of stored food Red Squirrels stash just before winter – sometimes at the base of a tree, sometimes underground.

Eastern Chipmunk

I love watching chipmunks…  I know that their behaviours are most likely all related to survival… but sometimes they just seem so playful.  And how can this – one of our smallest squirrels – be so loud in the woods?  When they rustle through dry leaves you would swear a much larger animal is nearby.

The first time someone told me that the fun cluck-cluck-cluck sound I heard in the woods – a sort of a cross between a chirp and a chuck – was from a chipmunk, I simply did not believe him.  But one day, I watched a little chippie making that sound.  (You can hear it by clicking here.)

Eastern Chipmunk by Me
Total Length: 9-10.5  inches
Tail Length: 2.5-4 inches
Weight: 2-4 ounces
Average Lifespan:  less than 2 years

Eastern Chipmunks (Tamius striatus) are omnivorous supplementing their diet of nuts and seeds with earthworms, slugs, insects, bird eggs, and baby birds.  Unable to lay down fat stores in the body like a true hibernator, chipmunks store dried foods in underground homes for consumption in winter.  The pouches in in a chipmunk’s cheeks can expand to the size of its head and hold hundreds of seeds.

Chipmunks enter temporary states of torpor throughout the winter, but they can be seen on mild winter days foraging for food in the woods or at your birdfeeder.

Here’s a good link, geared at kids:
http://www.canadiangeographic.ca/cgkids/animal/2007_07.asp

Rodents and Squirrels

The best way to learn something is to teach it.  This week, I had to teach a lesson on squirrels…

Forty percent of all the mammals worldwide are in the Order Rodentia or Rodents, over 2,000 species.

To be a rodent, you must have four incisors in front – two top and two bottom – which never stop growing throughout your life.  As you gnaw on things, they wear down, so the constant growth is necessary.  These incisors have a hard enamel on the front with softer material behind which makes them wear unevenly resulting in sharp, chisel-like edges.  The faces of your front teeth are yellow or orange.

Porcupine Skull Replica
Porcupines are rodents, but they aren’t squirrels.

Behind the incisors there is a gap with no teeth at all.  The gap is called the diastema.  In back you have “cheek teeth”.  The bones and muscles in your jaw are arranged in such a way that you can either gnaw with your incisors, or chew with your cheek teeth… but you can’t do both at the same time.

Of all the rodents worldwide, a little over 10% are in the Family Sciuridae – Squirrels – around 270 species.

If you were a squirrel, you would have 4 cheek teeth on each side of the top of your jaw and 4 or 5 on each side of the bottom jaw, depending on species.

Chipmunk SkullYou would also have a well-defined post-orbital process.  Hunh?  What’s that, you say?  Well, on the top of your skull, just behind each eye, there is a slender, sometimes pointy projection from the frontal bone and skull-studying nature nerds (and I use that phrase with the utmost affection) call it a post-orbital process.

Woodchuck Skull Replica
Woodchuck and chipmunk skulls both have post-orbital processes.

There.  Now you know how to tell if you are a rodent or not, and specifically if you are a squirrel or not.

Learn more:

The information for this post comes mostly from Allen Kurta’s excellent book Mammals of the Great Lakes Region, available from the University of Michigan Press.  There are 10 species of squirrels in his book, but only 7 of them live where I live.

Over the next few days, I’ll tell you about “my” squirrels…