While our street-wise eastern gray squirrels probably still dream of the ocean-like expanses of unbroken forest where they once lived, gray squirrels are thriving in the sub/urban environment, where many other native species fail. How do they do it?
SKILL SET: For starters, squirrels have impressive physical abilities. Squirrels are, admittedly, rodents but they are most closely related to prairie dogs, woodchucks, and beavers –not mice and rats, or even porcupines, for that matter. Like most rodents, squirrels have clever hands; keen eyes, ears and noses; ever-growing, sharp teeth; and alert, inquisitive intellects (albeit encased in walnut-sized brains).
What distinguishes squirrels from other rodents is the long, bushy tail which serves as an eloquent communications device, a balancing pole for high-wire work, and a portable parachute, blanket, and umbrella. Should a squirrel be required to swim, as in the storied 1933 mitigation of a thousand gray squirrels across the Connecticut River, the squirrel’s all-purpose tail is also useful as a rudder. (Before you ask, no one knows why the squirrels swam the river; the going theory is food shortage).
Flying squirrels, red squirrels, and chipmunks, despite most of the same abilities, are much more rare in the urban environment; so what makes gray squirrels special? Part of the secret is the gray squirrel’s ability to make good use of both the ground and the tree canopy. However, watch a gray squirrel flatten itself against a tree and cautiously edge out of sight, but a minute later, there’s a little gray face peering down to see if you’re gone yet; you’ll know that there’s something more at work here.
COMMUNITY SUPPORT: Gray squirrel success is partially attributable to sharing territory in loosely-associated colonies. Colony members band together to drive off new squirrels, if there isn’t enough food for all. Gray squirrels will also drive off other species that are perceived as food competitors. This territoriality helps regulate squirrel population density.
In addition to protecting the food supply, colony living gives each member the benefit of the whole group’s knowledge and experience. Squirrels do learn by observing other squirrels. Thus, as soon as one squirrel figures out that those lumpy, tan things next to the bird feeder are good to eat, the whole colony is munching peanuts.
Colony members also share defense. Squirrels communicate via sounds and posturing, including dramatic tail waving. There is a special warning call for serious predators like the red-tailed hawk. The squirrel talk that you’re most likely to hear is a “chit-chit-chit-chit”, accompanied by an erect, twitching tail, which translates roughly into “go away, now!”. The squirrel’s remarks may be addressed to another squirrel, a neighborhood cat or you, if you’re interfering with forging or too close to a nest.
Living in a gray squirrel colony, though, is not all sweetness and light. Experts say that colony members have an alpha-beta hierarchy, and that the cause of inter-squirrel friction, predictably, tends to be food, mates, and territory. Further, sharing only goes so far; gray squirrels have been observed faking where they bury food in order to hide it from each other.
SCATTER-HOARDING: Gray squirrels certainly do get a boost by being able to rely on communal food stores. Gray squirrels are “scatter hoarders” in that they do hoard, but don’t create central caches. Gray squirrels, instead, spread their stores over their whole territory, minimizing the risk of loss of a significant part of the year’s harvest.
Gray squirrels remember the general area where they buried things but find the exact spot with their super-noses, even through several inches of snow. Since there are only so many places to bury stuff in the sub/urban environment (e.g. my friend’s window box), a canny squirrel can usually find something that she or someone else stashed.
The forgotten “left-overs”, of course, are tomorrow’s oaks, hickories, pines, dogwoods, and crabapples. All that scattering and burying makes the gray squirrel an important seed-disperser for nuts and other large seeds. It seems that oaks need squirrels as much as squirrels need oaks.
FLEXIBLE DIET: Gray squirrels greatly benefit from food adaptability. Gray squirrels can be characterized as “food-turnal” in that they’ll adjust their schedules to the food supply. Given a choice, though, gray squirrels prefer to forge early morning and late afternoon, thus avoiding mid-day summer heat (they are wearing fur coats!) and night-time predators. During the frenzy of fall acorn-gathering, when the hawk isn’t around, you can often glimpse an exhausted squirrel sprawled on a sunny branch catching a well-deserved mid-day nap.
Gray squirrels recognize a wide range of foods and readily accept new foods. Young squirrels learn what is good to eat and how to store food by experimenting and by watching their parents and other squirrels.
In spring, gray squirrels live on tree buds, roots, flowers and stores. If stores run out, early spring can be a hungry time. Red squirrels are said to be adept at tapping sugar maples for the high-carb spring sap. There are mixed reports on whether gray squirrels have widely perfected this art but my local gray squirrels appear quite good at it.
As the year progresses, there are fruits, seeds, roots, and mushrooms to help tide the squirrels over until the nut harvest. Summer is a lean time for squirrels, though, so if you’d like to keep them out of the garden, it’s good to supplement their food (e.g. with a mulberry or wild cherry tree, or a squirrel feeder). Don’t forget a water source for them and the birds.
Squirrels are mostly vegans, but young squirrels, in need of protein and calcium, also eat insects, bird eggs, and small critters. City squirrels will eat a good part of whatever ends up in the trash.
Even urban gray squirrels are dependent on acorns and other nuts that will last all winter. Squirrel populations, therefore, absent bird feeders, rise and fall with the nut harvest which varies widely from year to year.
Because squirrels fixate on one or two available foods at a time, it is much harder to get a squirrel to stop eating bird food than to keep it away from him entirely. Thus, it is best to start with a reasonably squirrel-proof bird feeder and take more action at the first sign of squirrel interest.
EFFICIENT NEST BUILDING: In a few hours, a gray squirrel can craft a serviceable summer nest that will last a year or more. Gray squirrels construct leafy nests out of freshly-cut twigs with the green leaves attached. The leaves curl as they dry, creating a snug, water-resistant nest. There are usually plenty of summer nesting sites since leafy nests can be built in most trees over 12 feet tall. Adaptable as they are, squirrels will also use man-made articles for nest building– I’ve seen plastic bags, newspaper, duct tape, mattress-stuffing, and even a man’s shirt.
Gray squirrels construct at least one substantial summer home but may also make some slap-dash temporary ones, for example, near a seasonal food source. In addition, gray squirrels have learned the wisdom of maintaining back-up shelters so they won’t get caught out in potentially-fatal cold or wet if the primary nest is destroyed or invaded. Some experts estimate the gray squirrel population at 1.5 leafy nests per squirrel.
Winter housing is a problem for urban squirrels and, thus, another check on population density. A gray squirrel needs least one safe, water-proof, wind-resistant winter home. The traditional dwelling is a tree hollow at least 12 inches deep and 6 inches wide, with a 3-inch wide door. The best winter nesting trees are dead or half-dead standing trees, called “snags”, which are a natural part of the forest. However, in the ‘burbs, snags are often removed as unsightly or dangerous.
If tree hollows are lacking, squirrels have to find other winter accommodations or move on, a risky undertaking, and the cause of many late-season squirrel deaths. The next best choice, from the squirrel’s perspective, is a human structure. A squirrel nesting box, placed away from the house, is a fine way to share but the attic is not. When a wild animal gets in the house, the encounter seldom ends well for the animal, and can be upsetting and costly for the human. It is best to keep our furry friends out of places where they don’t belong by capping chimneys, screening windows, keeping garage doors closed, and annually inspecting building exteriors for gaps to seal.
Sidewalk watchers do see gray squirrels frequenting their leafy homes in winter. It is not known whether these squirrels are using the summer homes for food storage, day-time naps or over-wintering due to a shortage of proper winter quarters.
GROWING UP FAST: Surveys show that, in the ‘burbs, 75% of gray squirrels die their first year. Those that survive the first year to become parents are the smartest, fastest, and luckiest.
Historically, gray squirrels had two litters a year; however, with warming temperatures, a third litter is possible. The cold-season babies are conceived in January or February, born nearly hairless and blind 44 days later, nurse for about 6 weeks, and leave the nest as teenagers by May. They are not fully grown until the fall, when they turn 9 months old. Gray squirrels can conceive as early as the following January. While gray squirrels in captivity can live up to 20 years; in the wild, a gray squirrel is considered “old” at 6 years.
After the teenagers leave the nest, they have to find unoccupied locations to construct their summer and winter shelters; gather food, and be safe from predators. It is critical that the young squirrels quickly learn their territory so that they don’t use too much energy finding food, and so that they know the local dangers and the means to avoid them. A single mistake during the learning process can result in the young one ending up as hawk lunch or road kill.
PLAYFULNESS: The above observable, measurable qualities explain how gray squirrels survive in the urban environment. What these traits don’t explain is why gray squirrels tease dogs, bat tulip flowers back and forth, and perform death-defying feats to break into a bird feeder when there’s other food available. Nor do these measurable things explain why we so enjoy watching them do it. It’s a quality of the spirit, I think. Gray squirrels are definitely industrious, inquisitive, inventive, and stubborn, but there seems to be joyfulness, too. Could it be that the gray squirrels’ true secret is their playfulness or even a sense of humor?
Do you have a favorite gray squirrel story to share? What’s your take on our furry friends? Please click to leave a comment and join the discussion. We can’t wait to hear from you.
PS: Squirrel National Appreciation Day is Jan 21.
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