312 Townsend, Notes on the Rock Dove. [july 



from a height beat their wings behind the back with a rapid motion 

 which produces a loud whirring noise." As Pigeons that are not 

 suddenly disturbed rise from the ground silently, is it not possible 

 that this loud clapping, made perhaps when the bird is frightened, 

 may subserve a useful purpose in confusing a crouching animal 

 stealing through the grass, and thus prevent its springing at its 

 prey? Be this as it may, it is evident that, as in the case of the 

 Knot, the clapping is at times a courtship action, for, with puffed 

 out neck and breast, a male may fly with loud clapping to alight 

 near a female. 



The facts that when well under way in the air Pigeons extend 

 their feet behind under the tail, although they carry them in front 

 for short nights, and that they extend the bastard wing as they 

 glide towards a perch can both be verified by any one with ordinary 

 vision. I have already discussed these points in other papers. 1 

 It is interesting to speculate that this extension of the bastard wing 

 may point back to the time when the reptilian ancestors of birds 

 grasped with their front extremities the perch to which they were 

 gliding. 



The aerial evolutions of a flock of Pigeons are performed with 

 as great precision as is seen in flocks of Shore Birds, Gulls, and Auks, 

 — all relatives of Doves in the group of Charadiiformes. It would 

 seem as if the birds possessed a common mind as each bird in a large 

 flock suddenly turns with military accuracy first its back then its 

 breast to the observer, while the flock sweeps on, now this way, 

 now that, about a church tower. This sudden turning is accom- 

 plished by a rotation of the body along an antero-posterior axis 

 through the arc of a quarter to a half of a circle. The flock, flying 

 by an observer with the nearer wings pointed downwards at an 

 angle of 45 degrees below the horizon, suddenly changes so that the 

 nearer wings point upward at an angle of 45 degrees with the hori- 

 zon. With this change in position or "reverse" the color of the 

 wings appears to change from greyish blue of the upper surface to 

 silvery white of the lower surface. Dewar 2 has studied these evo- 



» The Position of Birds' Feet in Flight, Auk, XXV, 1909, p. 109. 



Bird Genealogy, Auk, XXIX, 1912, p. 285. 

 2 Dewar, J. M. The Evolutions of Waders. The Zoologist, 1912, 4 ser., 

 vol. XVI, p. 161. 



