I don't know the type of bird in our chimney, but I have been told they are swallows. How ironic I recently channel surfed and stumbled upon "Wonders of Mexico": the episode revealed a underground cave with a bird colony of "Cave Swallows" many people mistake them for bats. Fifty-two-(52) birds! Yes, I counted that many birds swooping down into our chimney. I knew we had birds in our chimney, but not that many - I fear there may be double of my count. These birds are not migratory because I hear them in the winter when we use the fireplace. Approximately 6 to 8 weeks ago in the early night I heard a lot of noise on top of our living room roof - I looked out the window and I believe I saw either a Owl or Hawk. I am hoping one of these big birds are hunting the birds in our chimney! I have also noticed a lot of feathers strewn in our lawn.