Inspection Unit 4C

Prevention and Species

Inspecting for Gray Squirrel Damage

This lesson consists of key facts and clues that will help you decide if the damage you are seeing could have been caused by this animal. These are key clues but they aren’t necessarily complete. (Humans are learning more all the time and animals change their habits, too). It should give you some pointers to at least help you rule out this species as a suspect in your situation.

Biology: Weight: 11.9-23.8 oz.

Diet: Assortment of nuts, fungi, bulbs, flowers, etc.

Habitat: Generally urban and deciduous forests.

Activity: Diurnal (daytime) / Year-round

Reproduction: Mating occurs twice a year. First time occurs in Jan/Feb with young born in April/May and weaned in June/July. Carl Carnahan of Oklahoma noted that a first season litter occurred around February 28. Kirk LaPierre of New Jersey noted a first litter on March 1. Second mating occurs in May/June with young born in July/August and weaned in Oct/Nov. The female raises 3 to 5 young alone.


A. Noises in walls and attic: Typically, the customer will complain about something scratching in walls or scurrying in the ceiling above. Often this will occur in the late evening or early (predawn) morning during the colder months of Sept-April. The noises may not necessarily be heard every day.

B. Noises in cellar/chewed windowpane wood: See Special Situations.

C. Noises in fireplace: See Special Situations.


Average hole size: Hole will vary in size from 1 to 3 inches in diameter. The longer the animals have been there, the closer the size will be towards three inches. Typically the holes will be found at the corners of eaves, under overhangs, in mushroom vents, and in attic vents. The key here is to look up. Of all my squirrel jobs, only two had squirrels entering at ground level. Check these areas closely with your flashlight. Look for the absence of mosquito netting and brown smudges visible on the vents. These brown smudges are caused by the body oils wiping off onto the vent as the animal squeezes through it.

Access: Gray squirrels, like most creatures, will always use the easiest way to enter a building. Typically, they access buildings from overhanging branches. If no branches are available, they will use power lines (usually if they are taut) and aluminum gutters. In these situations, look closely at the gutters for small ¼- to ½-inch long scratches in the paint. The scratches will look like they have been made by a pin. So be sure to look very closely at each of the gutters, especially the ones that reach all the way to the top of the roof. (Photo by Stephen Vantassel)

Damage to house: If you enter the attic area, look for the pink fiberglass insulation that will be stripped to the paper. This is a classic sign of gray squirrel. If damage is caused by mice or rats, you will most likely see droppings. On rare occasions, you will notice chewed beams, rafters, and wiring. Usually these signs are found when the house has had long-term problems (i.e. years of untreated squirrel problems or multiple infestations). In these kinds of heavy damage, you will often be able to smell the squirrels. Get to know that smell as you will probably smell it again. Another sign is when the homeowner complains that a small hole is appearing in the ceiling and growing larger each day. Gray squirrels will also chew lead flashing used around chimneys and walls.

Damage to lawn/garden: Generally damage will be minimal. Occasionally, you will hear complaints about squirrels digging up the grass when they bury or uncover hidden acorns. When food is scarce, squirrels will also eat flowers, pumpkins (to get the seeds), and even tomatoes. The damage often can be alleviated by removing the items. In other situations, ignore it. Squirrels can also chew cans to get inside or just to gnaw down their ever-growing incisors.

Feces: You will not find abundant fecal material in an attic. Squirrels, unlike raccoons, don’t have toilets per se. Any feces found will probably be few and far between. Generally, the feces looks like a black piece of rice. Sometimes it will be more round like an enlarged brown BB pellet.

Tree damage: During dry spells, gray squirrels will strip bark to get at the moisture underneath the bark.  You can also distinguish this damage from that of porcupine by looking for droppings underneath the damage. Porcupine droppings are larger than squirrel droppings, says John R. Consolini.

Miscellaneous: Squirrels can climb, bricks, stucco, wooden shingles, aluminum downspouts, and power lines. (Photo by Stephen Vantassel.)

Tracks: See a book on animal tracks.

Diseases: During the springtime, April/May, pregnant females will remove fur in order to line their nests. Don’t mistake this for mange, etc., which will make the skin crusty and full of sores. Clear skin doesn’t guarantee nesting is the cause but it should be considered.

Special Situations:

A. Noises in the basement: Sometimes the owner will tell you that they have heard noises in the basement and items on shelves have been knocked over. Typically this occurs in the months of December through February when female squirrels are looking for a nest to raise young. Often it will happen just before an impending snowstorm. (90% of the time the furnace will be fired with gas, not oil. New Hampshire has the opposite stats). Ask the owner if he has branches overhanging his house/chimney. Again, the majority of the time he will say yes. Don’t trust him when he says his chimney is capped. Often people don’t know what capping means or they screened the chimney 10 years ago with hardware cloth that has long since rusted through or blown off. A careful look at the draft diverter (in gas furnaces) will often reveal small smudge marks where the squirrel climbed out. Once in the chimney, the squirrel cannot climb back out because the flue tile is too smooth.

If there is damage to the window pane wood or to bottom of a basement door, then you know that a squirrel has been trapped inside. Generally speaking, squirrels cannot live much longer than 3 days without water. There have been exceptions, but they are less than 10 percent.

B. Noises in Fireplace: This one is trickier because it could be caused by a raccoon, bird, or squirrel. Ask the owner if there are overhanging branches. If there are, then that is one more clue for squirrel. Ask if they heard any fluttering. If so, then it is a bird. If the call comes in during April, ask if they heard any chirping. If yes, than it is raccoon. Before looking down the chimney, look at the sides of the house for access. Try to rule out other animals. In the final analysis, you will need to open the damper and use your mirror to see if it is squirrel. Sometimes the squirrel will look over the side of the damper to take a peek. Be careful, as squirrels sometimes run out once they see the light. Make sure breakables are out of the way and that you have sectioned off the area by closing doors. Remember, just because you cannot see an animal from the top of the chimney, doesn’t mean one isn’t there. Many times animals are off to the side out of view. Always keep in mind that the smoke chamber is usually larger than the flue.

C. Don’t be misled if you see birds using a hole in the house. I have had at least one job where birds and squirrels used the same hole to enter their nests.

©2005 Stephen M. Vantassel

Unit 4D