Standing by your kitchen window one morning, you notice a gray squirrel in the yard, busily tucking fallen leaves between his throat and chest. "Ah, he's making a nest," you think, "isn't that nice". The squirrel, carefully tending his load, hops over to the tree outside your window and scrambles up out of sight. But then was that a "thump" on the roof? The sound of little toenails scrabbling across the shingles, and oh no! a rustling in the attic! Rushing outside, you find a neat little hole chewed in the lattice vent in the roof peak. Your attic has become a squirrel den.

Four squirrel species occur in Maryland - gray squirrel, red squirrel, flying squirrel and fox squirrel. Gray and flying squirrels are the most abundant and cause homeowners the most problems.

Habits

Gray squirrels are active in the daytime and, therefore, are more readily observed than the nocturnal flying squirrel. In most other ways, their habits are similar. Breeding seasons occur in January and June. At these times, gray squirrels can be seen noisily chasing each other through the trees. The female bears three or four young, which are dependent on her for about three months.

Squirrels are associated with mature trees, where they normally find their food and lodging. Gray squirrels prefer tree cavities for winter dens and raising young, but will construct leaf nests, 12 - 16" in diameter built in tree tops, to use in spring and summer. Flying squirrels use only tree cavities. Their food is primarily acorns, nuts, berries, fruits, buds, and occasionally fungi, bird eggs or nestlings.

Vocal and animated, gray squirrels play and chase each other, often barking and chattering. They also scold intruders, such as dogs, cats or people, from a safe perch. In suburban and urban areas, they become quite tame and can be approached very closely.

Conflicts

The squirrel's most damaging habit is gnawing entrances into attics. Once inside, they often use insulation or other materials found in the attic for nest building. Occasionally, they chew electrical wiring and cause short circuits and sometimes fires. Less frequently, squirrels mistakenly end up in the living area of a house. They find their way in through an open damper in a chimney or travel through the walls to the basement. Squirrels can also become trapped in chimneys. Nesting in houses is usually the only problem that flying squirrels cause.

Gray Squirrels raid fruit and nut trees, and occasionally vegetable gardens. They find flower gardens very attractive, and they eat both flower bulbs and buds. Tree leaves and twigs may be trimmed from trees for nest building, and bark gnawed away for reasons unknown.

Squirrels bury nuts and acorns, sometimes in lawns. The problem arises not from the burying because buried nuts are well hidden. However, when the nut is retrieved, the squirrel doesn't bother to fill in the hole.

Preventing Problems

Squirrel populations often build up to high numbers in older residential areas which have lots of mature trees, particularly oaks. Because their reproductive rate is so high, live trapping is not usually effective. A homeowner's best bet is to protect his house by screening openings and removing access to food sources, such as bird feeders.

Attic louvers, vents, and fan openings should be screened with one-quarter inch mesh hardware cloth. Window screening is not sturdy enough to prevent their entering. Eaves should be closed up tightly and rotten boards replaced. Chimneys should be capped.

Squirrels nearly always enter houses near the roof line. Oftentimes, they can be denied access to the roof of a house by trimming overhanging tree branches. All branches within six feet of the roof or walls should be trimmed. Before considering this approach, bear in mind that squirrels can easily climb textured surfaces, such as brick or rough-cut siding. Aluminum siding and smooth, painted surfaces are not so easily scaled.

A yard can be made less attractive to squirrels by removing as many food sources as possible. This means no bird feeding or using squirrel-proof feeders. A number of squirrel guards for feeders and squirrel-proof bird feeders are on the market. Check hardware and garden stores and wildlife-oriented catalogs to see what is available. One method for protecting feeders mounted on a single post is a cone-shape sheet metal guard. For this guard to be effective, the feeder must be at least 5 feet above the ground and placed so that squirrels can't jump on it from above.

Fallen acorns and other nuts can be raked up and removed from small yards. This removes one source of attraction and reduces the problem of squirrels digging in the lawn. They usually will not carry acorns very far to bury them.

Control

The arsenal of weapons for controlling an onslaught of squirrels is varied, but the best may be your own inventiveness. The following information will help you plan your attack. Keep in mind, however, that trapping to reduce populations is generally not effective and poisoning is illegal.

Squirrels which have entered attics can often be chased out with a broom and the entrance closed. When the den area is inaccessible, trapping is about the only alternative. The live trap should be placed as close as possible to the squirrel's entranceway. Peanut butter is a very good bait. When removing squirrels from January through early September, remember that young may be in the nest. If you have access to a nest with young, put the whole nest in a box and put it outside near the entrance in a safe place. The mother will take them to a new location.

Squirrels which have found their way into the living area of a house can usually be encouraged to leave by darkening the room and opening a door or window to the outside. It may take an hour or two for the squirrel to get up enough nerve to leave. A squirrel trapped in a chimney can free himself if a rope is hung inside the chimney from the top.

Keeping squirrels out of fruit and nut trees is a difficult task. Tall fruit and nut trees can be protected by trimming away lower branches that come within six feet of the ground and then placing an 18" long sheet metal cylinder around the trunk. The top of the cylinder should be about four and one-half feet above the ground. Groves of dwarf trees can be protected by an electric fence of the type used for livestock. Place three or four strands at 4" intervals on metal, not wooden, stakes.

A number of methods can be used to protect flower gardens. The most effective method for protecting flower bulbs and preventing digging in gardens is placing one inch mesh chicken wire over the bed before bulbs sprout in the spring. The flower shoots will easily find their way through the mesh. A number of commercial repellents are on the market which claim to repel squirrels from flower beds and shrubs. They are available at hardware and garden stores.

Squirrel's twig-trimming and bark gnawing activities usually do not do long-lasting damage to trees. Large patches where the bark has been removed should be coated with a tree-pruning paint.

Diseases

In general, squirrels carry no diseases that are easily transmitted to humans. It is subject to rabies; however, rabies in squirrels is very rare. Any squirrel that is exceedingly aggressive, lethargic, has trouble moving, or is immobile should be avoided.

For more information, please contact:

Maryland Department of Natural Resources
Wildlife and Heritage Service
Tawes State Office Building, E-1
Annapolis MD 21401
410-260-8540
Toll-free in Maryland: 1-877-620-8DNR, Ext. 8540

Photo of Squirrell Bird Feeder
Courtesy of GustavoG, flickr