Today I rescued a Black Capped Chickadee that "fell" into my bird feeder. I presume it tried to reach the seeds that were below the feeding hole and tumbled in. I had been looking at the feeder through my binoculars and notice the litte guy flapping around inside the feeder. I opened the feeder and he (she) flew away, unharmed. Good thing I happened to be looking. It would have had plenty to eat, but I don't know about the other survival requirements.