John Alcock, Animal Behavior: an Evolutionary Approach, Sinauer Associates, 1998

(Top) Baffles deflect the wind 90 degrees, thereby altering a caged pigeon's perception of the direction from which certain odors come. (Bottom) The initial orientation of pigeons kept in deflector lofts A and B is shifted by about 90 degrees when they are released to home back to the loft. Open circles show the orientation taken by each bird upon release; the arrow within the circle shows the mean orientation taken by all the experimental birds.