Bird nests with or without birds in them are a health and fire safety problem for your home. Bird droppings are not only unsightly in your fireplace, but birds can also carry mites and parasites into you home.
One note: Chimney swallows are federally protected birds.
How to Get Rid of Bird Nests in Chimney
Whether to wait until any nestling are gone or not is up to you. Be aware, however, that barn swallows, which are one of the most common birds to nest in home chimneys, hatch in 15 days and the young continue to use the nest for up to three weeks. Typically, a second brood is hatched while the first brood is still using the nest, as the older siblings help feed the new baby birds. You will recognize barn swallows by their characteristic forked tail and barn swallow nests by their cone or pocket shaped mud nest plastered to the vertical wall of your chimney.
Another choice is whether to do it yourself or bring in a chimney sweep to remove bird nests from a chimney. Some bird nests can be easily removed by any homeowner willing to go up on the roof. Others, such as barn swallow nests, require scraping the nest from the interior of the chimney, a messy process that can drop unsanitary and possibly mite-infested material into your fireplace. (See Dangers of Bird Droppings in Chimneys.) If you do this type of bird nest removal yourself, we suggest you take your shop-vac to the roof and use it to catch bird nest debris as you remove it.
Whether you remove the bird nest yourself or hire a chimney sweep to do it, it is imperative to remove any nests or remaining nesting materials before using your fireplace in the fall. Combustible material inside your chimney flue and a burning fire are not a good combination!
But bird nests in chimney need not be an annual concern. A damper that seals the top of your chimney , such as a Lyemance damper, can prevent any animal, including birds, from using your chimney for shelter or nesting purposes. Such a chimney damper can be opened when you have a fireplace fire.