"The most effective way to learn bird songs is to listen to recordings made in the field and produced commercially as cassette tapes or discs.  The best ones are made by the Cornell University Laboratory of Ornithology and published by the Houghton Mifflin Company.  [Check other sources; update this information.] 

A lot of ornithologists write lyrics for bird melodies ~ actual words and sentences that birds would use if they could talk instead of just whistle. 
"Here are a few of the more famous results:  Drink your tea ~ (rufous-sided towhee), Old Sam Peabody Peabody Peabody! (white-throated sparrow), Teacher Teacher Teacher! (oven-bird), Sweet, Sweet Sweeter than Sweet! (Yellow warbler), Quick Three Beers! (olive-sided flycatcher), Pizza! (Acadian flycatcher). "

Our Mum always heard Polly, Polly put the kettle on when the oriole sang.

~ Wild Birds of Canada, Tim Fitzharris, Toronto Oxford University Press, 1989.