And then there is the advantage of having a clearly identified  
birder's car.  Censusing Upland Sandpipers, many years ago, on an  
early Sunday morning, a local protector of the public pulled up beside  
me to ask what I was doing.  He was skeptical until I pointed out the  
Audubon and Cornell Lab of Ornithology stickers on my back window.   
Huge release of held breath.