Don Borror recorded Alan Cruickshank, renowned ornithologist and photographer as well as instructor at the Audubon camp on Hog Island, Maine, imitating bird songs. Have you ever tried to imitate a Barred Owl, American Bittern or Black-billed Cuckoo? Listen to Alan Cruickshank imitating bird songs (5 min) during a program on Hog Island, Maine:
And here are bird notes (30 min each) from Don Borror. As he describes them himself "a random selection of bird songs from field tapes with behavioral observations". You may be surprised to hear a cow and some chickens mixed in.
Borror Notes Side A
Borror Notes Side B