To a nearby critter, climbing up your chimney is no different than climbing a tree. Without a chimney cap and mesh screen to keep them out, small animals like birds, raccoons, squirrels, and even pests will crawl inside the flue. When one small animal moves into your chimney, it often attracts other visitors. It doesn’t take long to have an infestation.
If there are unwanted visitors in the chimney, you may hear them scurrying around in the evening. They may be scratching, gnawing, or squealing when frightened or trying to get out of the chimney. You may hear small birds or bats flapping their wings against the side of the flue. Some small animals get stuck and are unable to escape. Others like rats or mice may climb down the flue and enter your home through the fireplace with an open damper. Since they also bring in dirt and debris and leave droppings while inside the chimney, it is often a source of foul odors. So, if you hear scratching sounds at night or it’s getting pretty smelly inside the fireplace, you may have some unexpected visitors living in the chimney.
Installing a chimney cap will keep small birds, animals, and pests from entering the flue. It will also keep out water and debris like small leaves and twigs. They are inexpensive and are available in different designs that can also enhance the appearance of your chimney. Look for caps that have a mesh screen. It allows the smoke and contaminants to vent while keeping out unwanted visitors. Many chimney caps also have a spark guard feature that prevents hot embers from flying out of the chimney and landing on the roof.
Check your chimney cap at least once per year during your annual chimney inspection. A damaged chimney cap should be repaired or replaced as soon as possible to protect your chimney.

Small animals in the chimney
Install a chimney cap