LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS. 17 



kittiwakes to be the chief source of its supplies, as also is the case in 

 Baffin's Land, for Kumlien (1879) says: 



This species seems tp depend on Rissa tridactyla for the greater part of its 

 food. 



Anderson (1913), under the heading "Parasitic jaeger," says: 



The jaegers are the terror of the smaller birds, spending their time cease- 

 lessly hawking back and forth over the tundra looking for eggs and young 

 birds. Large numbers of eggs of eiders and gulls are destroyed in the rookeries 

 by the jaegers. Whenever the Arctic terns are nesting their neighbors are com- 

 paratively safe, as the belligerent little terns speedily cause any marauding 

 jaeger to beat a hasty retreat. I have also seen ruddy turnstones drive a 

 jaeger away from the nests. I once observed a pair of jaegers chasing a flock 

 of sandpipers. One sandpiper flew out of the flock, the jaegers in pursuit. 

 They seemed to work together, one darting in while the other turned. The 

 sandpiper finally escaped by flying upward until almost out of sight, and the 

 jaegers finally gave up the chase. * * * Some other birds will also attack 

 the jaegers, which are really cowardly birds when heartily opposed. I have on 

 two or three occasions seen a rock ptarmigan fly fiercely at a jaeger which 

 came too near his nesting place and put the jaeger to ignominious flight. 



Its calling makes it one of the most interesting sea birds to 

 watch. The advent of a jaeger among a flock of terns occasions 

 loud cries of anger among the latter as they scatter to the right 

 and left, while the hunter, singling out one individual, chases it 

 with great energy. No matter how skillfully and rapidly the vic- 

 tim twists and turns, now up, now down, now to one side, now 

 the other, sooner or later, with a few exceptions, it acknowledges de- 

 feat by dropping the fish from its beak or by disgorging the con- 

 tents of its gullet. These, the jaeger, with great skill and agility, 

 catches in mid-air and swallows at once, or on other occasions car- 

 ries hanging from the beak for a short distance before satisfying 

 its appetite. Sometimes it alights on the water, the better to enjoy 

 its meal. Nelson (1887) says: 



They are very greedy, and frequently swallow so much that they are unable 

 to fly until a portion is disgorged. 



The victimized tern meanwhile vents its wrath at the robbery in 

 no uncertain language and must again set to work for its living. 

 But the jaegers are not always successful. Thus, on one occasion, 

 I saw a parasitic jaeger pursue a common tern in a straight line for 

 nearly a mile, eventually to give up -the chase. Not infrequently 

 two hunters combine on one victim. Thus I have notes of two 

 jaegers at Ipswich, one in the dark, the other in the light phase, 

 that relentlessly followed a common tern. The bird that secured 

 the prize was at once pursued by his companion and accessory in 

 theft On another occasion two jaegers at Ipswich were chasing 

 a tern that twisted in sharp angles and small circles over the beach 



