Birds are a common and potentially serious hazard inside chimneys, especially in older or badly maintained chimneys that may not have any of the necessary precautions in place to prevent access. Open chimneys present what appears to be an ideal nesting area for many bird species, but using the fireplace or furnace to which it is attached will most likely kill the birds. In addition, nesting materials and the birds themselves present a major hazard for chimney fires and blockage. The age-old method of smoking birds out can be effective, but it will kill any flightless young or small animals, such as raccoons that may have gotten into the chimney. This method will also kill any bird that cannot find its way back out or that does not have enough space inside the chimney to spread its wings and fly out. Instead, there are safer, more humane ways to get birds out of your chimney. If these fail, consider calling a professional wildlife-removal service or the local wildlife authority to help safely remove the birds.
Compel birds to leave on their own
There are two approaches you can use in compelling birds to leave the chimney-either drive them out or draw them out. Driving birds out of the chimney employs the same concept as smoking them out, but with a little bit safer method to get them to fly away. Open the dampers wide and place a tray directly below the chimney's mouth. The most effective and highly recommended substance to pour into the tray is ammonia; it won't hurt the birds, but the unpleasant smell will push them to go elsewhere. Most household cleaners contain ammonia, but use with caution as some of the other chemical fumes may be toxic. Alternatively, place birdseed or another compelling treat below the chimney to try to lure the bird down into the fireplace. Leave the fireplace door open and open a nearby window. The bird will be attracted to the light and will very likely fly toward it instead of back into the dark chimney. Make sure either of these methods is used in the fall after young have left the nest or in the early spring before nests are built.
Remove birds by hand
Many chimneys have a ledge formed into them not far up the length in order to prevent downdrafts from interfering with your fire. This is generally where birds will build their nests. If the size of the chimney allows, you can carefully reach in and remove nests or even adult birds by hand. Make sure you wear sturdy gloves that will protect you from any pecking, and gently hold the bird's wings against its body until you have it outside so that it doesn't injure itself. Nests with young in them can be placed in a sheltered roof space near the top of the chimney so that the parents can find them, or turned over to the care of the local wildlife authority. Contrary to popular belief, wild birds will not reject their young simply because they have the smell of humans on them; they will readily continue caring for the babies if they can find them.
Prevent birds from getting back in your chimney
The best solution is always prevention. To keep birds out of your chimney in the future, simply have it fitted with a screened cap. This will prevent wildlife access and will also work to keep debris from blowing into the chimney. A chimney cap also serves as an additional guard against downdrafts and keeps ash and sparks from floating out. Regular cleanings will alert you to any damage to the chimney or cap that needs to be repaired.