Wildlife Spotting

"The Broken Arm Bird" - Mystery Night Bird.

I moved to Savannah, Georgia in 2004. On the night of April 18th I heard for the first time a strange bird that I have not been able to identify, even 7 years later.

What I do know is that it's nocturnal, and only frequents the low country of Georgia/South Carolina from April to about June. It sounds large. I have never actually seen it, as it is always dark when it's around. My wife and I refer to it as the "Broken Arm Bird" as the first night we heard it I had broken my arm. I included a recording below. Can anyone identify this mysterious bird?

http://dl.dropbox.com/u/11504704/Broken%20Arm%20Bird.mp3