Spring is upon us and mother raccoons are on the move, in search of suitable nursery accommodations in which to give birth and raise their new litters. One of the best nurseries known to raccoons may be attached to your house. Uncapped chimneys offer excellent amenities—they're snug, safe, and quiet—and make for perfect dens.

Fortunately for homeowners who don't want to open a raccoon day care, prevention is simple: A secure chimney cap will keep raccoons out before they settle in.

Raccoons look for tall structures they can enter from the top with protected interiors where mother and young will be safe from predators. Raccoons learned to look for these features in hollow trees long before people built chimneys. An abundance of chimneys—and corresponding short supply of hollow trees in cities and suburbs—is a recipe for conflict with these wild neighbors.

Although raccoon-human conflicts are widespread during "baby season," it doesn’t have to be. An ounce of prevention is worth a pound of cure: By simply capping your chimney, you can ensure that your flue doesn't become a home for these animals. Raccoon birthing season generally begins in late March and continues through the spring, so the sooner the better.

Here are some tips for chimney capping:

• A simple test with yesterday's newspaper will assure that no animal is living in your chimney. Tape a piece of newspaper over the top of the chimney leading to the fireplace, and check it 48 hours later. If the newspaper is not torn away, you can be sure your chimney is raccoon-free. Never cover the top of a furnace flue. Doing so can cause carbon monoxide to build up in the house to dangerous or even lethal levels.
• If you find evidence of a raccoon in residence, your first option should be to play the waiting game. Wait until her family has moved out before capping the chimney. Waiting a couple of months gives the babies a chance to mature so they can survive on their own. (If, for whatever reason, you simply can't wait, see ** below.)
• Home and hardware stores sell caps that homeowners can install themselves. Chimney sweeps and similar services can also install them.

Homeowners should never start a fire in a fireplace if they suspect there may be raccoons or any other animal in the chimney. Since adult raccoons are slow climbers, smoke can asphyxiate them before they reach the top. The raccoon may even fall back down the chimney and end up in the house. During the spring and early summer months, baby raccoons cannot climb up the steep chimney walls and will almost certainly die from the smoke, and the mother could never carry each young raccoon out of harm's way before some of her cubs died.

** Like any new mother, raccoons prefer a peaceful place to raise their babies, and gentle harassment can convince them to move their young to a new den. Because raccoons are nocturnal, harassment works best during the day when the mother raccoon is trying to sleep. Mother raccoons, however, will avoid moving their young in daylight when they feel vulnerable. Noise from a loud radio, lights, and smells can convince her that the chimney is no longer a good nursery. Try several techniques during the day, and chances are good your raccoon will move on the next evening.