Most birds have both songs and calls; complex songs are used to defend territory and attract mates, while calls are very simple. Bird watchers use catchphrases – known as mnemonics - to memorize bird songs.
 

Red-shouldered hawk - kee-ahh, kee-ahh

Blue jays - queedle, queedle, queedle

Red-winged blackbird - conk-la-reeeeee

American robin - cheer-up, cheer-a-lee, cheer-ee-o

Marsh wren - teakettle, teakettle, teakettle

Common yellow-throat - witchety, witchety, witchety