To LJ: not sure if ti's true, but I found this: "As The Crow Flies"-
Q- What is the origin of the term, “As The Crow Flies?”
A- The term “As The Crow Flies” came from British coastal vessels that customarily carried a cage of crows. Crows detest large expanses of water and head, as straight as a crow flies, towards the nearest land if released at sea - very useful if you were unsure of the nearest land when sailing in foggy waters before the days of radar. The lookout perch on sailing vessels thus became known as the crow's nest.
http://www.sailingscuttlebutt.com/news/trivia/ 
peer agreement (net): +4