MIGRATIONS OF WATERFOWL 



significant data supporting such opinions, and it seems appropriate to neg- 

 lect them until they are adequately tested." From the radar research of the 

 armed services come casual reports of birds, especially waterfowl, respond- 

 ing to radar pulsations. Poor (1946:631), reporting on the work of W. H. 

 Doherty, of the Bell Telephone laboratories, says "he had noticed that when 

 a radar transmitter was directed at a flock of flying birds, the birds appeared 

 to become confused, with the flock often breaking up and the birds wander- 

 ing aimlessly. Single birds also seemed to be disturbed." I have permission 

 to quote from a letter written by Brigadier General Homer Case, of the U.S. 

 Army, to Mr. Frederic C. Lincoln, of the U.S. Fish and Wildlife Service: 

 "The antiaircraft units of this command are equipped with high power 

 radars with a wave length of 10 centimeters. They conduct target practices 

 near Bethany Beach, Delaware, and flights of wild geese frequently pass 

 over that area. It is an interesting fact that when the beam of a radar is 

 aimed at a flight of geese, the 'V or other formation breaks up and the 

 geese fly off in all directions. As soon as the beam is moved away the geese 

 return to their original formation." 



"In the fall of 1943," writes Knorr ( 1954), "I was in charge of a group of 

 military personnel engaged in tracking aircraft over the ocean off the east 

 coast of the United States. The radar set was emplaced in the dunes not far 

 from the high tide line. During a lull in operation, a large flock of scaup 

 (Aythya sp.) and scoters (species?) was seen flying parallel to the coastline 

 a few hundred yards off shore and approaching our position. Having nothing 

 better to do at the moment, we idly swung the parabolic antenna around 

 and pointed it directly at the flock. The result was immediate and dramatic. 

 The once orderly group of birds became a bewildered mass of individuals 

 which flew in circles, missed wingbeats, and performed many unbirdlike 

 gyrations. Some observers later insisted that a few birds accomplished loops 

 and rolls, although I never observed this. As the beam was diverted by 

 elevating the antenna, the flock regrouped and proceeded down the coast 

 in the original direction. To verify this unusual behavior as being caused by 

 radar, the experiment was repeated several times on subsequent occasions. 

 In each case the result was essentially the same, the response of the stimu- 

 lated flock coinciding with the incidence of the beam upon the birds, the 

 cessation of response coinciding with the diversion of the beam." 



I hoped that we might study the problem at Delta,* and a radar set was 



• Our interest was stimulated by Dr. R. B. Roberts, of the Carnegie Institution, who observed 

 what appeared to be avian responses to radar during his wartime researches. 



188 



