A few mornings ago I stepped out the front door of my house in Maine. It was 5 AM and still dark outside but the sky was echoing with the flight calls of migratory birds. Rainy, foggy weather was causing migrating birds arriving from further north to come down to land as their neared the dawn and the end of their long night of flying. Most of the birds probably nested or were raised in the Boreal Forest of Canada this past summer. Using my iPhone I made a 5 minute recording of what it sounded like and which you can listen to at the link below. With the volume up high and with decent speakers or earphones/headphones (and no distracting sounds) you should be able to hear the plaintive "toow" of Hermit Thrushes, the spring peeper like sounds of Swainson's Thrushes plus lots of the lispy calls of Savannah Sparrows, sweet "seep" notes of Yellow-rumped Warblers, some White-throated Sparrows, perhaps a couple of Swamp/Lincoln's Sparrows and probably some other things too including a gang of noisy crickets.
Most people can't tell any of them apart, but it is still pretty cool to hear the chorus of short, high flight calls and to think that thousands of birds were overhead in the dark that morning!
http://soundcloud.com/birdwells/sounds-from-thursday-morning-1