For recordings of bird songs, call 612-673-7800, and when prompted press the following four-digit numbers:
1233 American golden-plover
1232 black-capped chickadee
1231 Northern waterthrush
1230 Swainson's thrush
Recordings from the Library of Natural Sounds, Cornell Laboratory of Ornithology. Try the lab's website: www.birds.cornell.edu.