A homeowner in the Midtown area called us in early May. She had heard chirping inside her fireplace for about two weeks. She had used the fireplace earlier in the spring, before the sounds started, and wanted to use it again.
The first thing I did was a visual inspection through the clean-out door and a camera pass through the top of the flue. What I found was a partially complete nest - sticks and plant fiber compressed against the smoke shelf - and two adult Chimney Swifts moving inside the upper flue column. Active. Nesting.
I explained the Migratory Bird Treaty Act on the spot. Active nests of federally protected species cannot be disturbed. Period. That's not our rule - it's federal law. She appreciated having the straight answer instead of a vague delay.
We documented the nest configuration, photographed the flue interior, and added her to our follow-up schedule for mid-August. When the birds departed, we came back. Nest material removal took about forty minutes. The flue blockage - a partial obstruction caused by accumulated nesting material, sticks, and dried saliva - had reduced usable draft area by roughly forty percent.
After clearing, we ran a draft test. Airflow was restored. Then we installed a stainless steel cap with the appropriate mesh gauge to block re-entry without restricting draft.
She had a working fireplace by September. The call we made in May made that possible.