They act like they own the place. They rummage through the strollers and chairs on your porch, they raid your trash, they steal your tomatoes, and they literally look down at you when you leave the house.
The gray squirrel is probably the native wildlife species we are most familiar with, and as we know, familiarity doesn’t always breed affection. Still, these acrobatic, intelligent, resourceful animals give us all a lot to study, enjoy, and admire.
Gray squirrels probably need no description. Some of them are black or intermediate charcoal colors. The only other squirrel to confuse them with is the much smaller (half the size) red squirrel, which is reddish-brown with a bold white eye lining. Red squirrels stick to conifer stands in our larger wooded parks and are uncommon in Philadelphia.
They are built for climbing. Their bushy tails help balance and stabilize them as they run and leap through the treetops or telephone poles, and their flexible wrists let them grip vertical surfaces whether they’re going up, down, or sideways.
Nuts and acorns are on the menu, of course, and squirrels famously bury their food. They don’t actually remember every acorn they bury, but instead find them by smell later. Squirrels also eat leaf and flower buds, fruit (including your tomatoes), as well as whatever they can pull out of the trash.
Gray squirrels are comfortable anywhere in the city they can find food and trees, or the artificial trees we construct for them out of utility poles and wires.
Gray squirrels build nests out of leaves and sticks in trees. These can look like some bird nests (crows for example) but are not open at the top, and tend to be leafier. They also nest in cavities in trees and buildings.
Squirrels give birth to 4 to 5 young and breed in summer and in winter.
Squirrels communicate with a variety of vocalizations, including “kuks” and moans that signal a predator approaching, as well as tail signals. These warn other squirrels of the danger and let the predator know they’ve been spotted. A house cat or a hawk might give up when it sees that an ambush has been ruined. When you hear a squirrel making a racket, look around and you might spot the predator too.
Cats and dogs sometimes catch squirrels, and Philadelphia’s red-tailed hawks also dine on gray squirrels. Squirrels will sometimes bark and “chuck” at predators, and communicate with other noises as well.
Human History with Gray Squirrels
Given how common squirrels are, you might be surprised to learn that squirrels were once quite scarce in Philadelphia. Starting in the mid-1800s, squirrels were intentionally introduced into Center City parks, and then exterminated once they were seen to raid bird nests. By the early 20th Century the landscape had become more squirrel friendly. Squirrels took advantage of street trees and wooded parks, they found great nest sites in houses, and they used telephone wires to cross dangerous streets and avoid dogs.
Squirrels are easy to watch. They are active when we are, and they live all around us. Listen as well. If you hear a squirrel making a racket, check to see if it is calling out a predator like a hawk or an outdoor cat.
Living With Squirrels
Squirrels don’t need much help from us. You can do them a favor by keeping cats inside and dogs on leash.
To avoid home squirrel problems, be sure to seal up any exterior holes in your house that squirrels might use to get inside and set up nests. Keep trash sealed up as well.
Squirrels often dig through planters, sometimes to feed on flower bulbs, but also to bury acorns. A barrier of chicken wire at or just under the surface of the soil can help protect your plants.
Defending bird garden veggies from squirrels is a perennial challenge. Short of fully caging your garden, squirrels will take their share and leave a half-eaten tomato up on a fence post to rub it in.
Read more about the gray squirrel’s urban history in this article by Philly historian Etienne Benson.
Learn about squirrels from the PA Game Commission.
Get started tracking animals and studying their prints, whether that's in snow, mud, or concrete. Thanks to our partners at Grid Magazine for producing the video.