LIFE HISTORIES OF NORTH AMERICAN PETRELS AND PELICANS. 145 



and finally discovered one " which was evidently digging into a 

 petrel burrow for either the egg or bird, or, more probably, both." 



Wi7}ter. — The young are so late in maturing that the petrels can 

 not wholly desert their breeding grounds until the latter part of 

 September or in October, but as soon as the young are able to fly 

 they start on their Avinter wanderings at large over both oceans, 

 but probably mainly in the northern hemisphere. Mr. Ora W. 

 Knight (1908) says that "a few stray specimens are reported in 

 winter" off the coast of Maine, "but at this season a majority are 

 wandering in distant oceans." Mr. Eich's notes show the appearance 

 of the Leach petrel, " single birds or in twos and threes, until October 

 12, when I left the grounds, and somewhere between this latter date 

 and October 23, my next return to Georges, the last petrel left these 

 banks, since my record shows no further note of their presence. I 

 am aware that there are records on inshore waters somewhat later 

 than this date." 



The following incident, related by Mr. I. I. van Kammen (1916), 

 is interesting as indicating a flocking habit which I have never 

 noted, though I have visited the same region: 



During a recent cruise to the Pribilof Islands via soutlieastern Alaska two 

 such flocks of " whale birds " were observed in company with scliools of whales, 

 and were noteworthy in that each flock consisted, in as far as I could see, of 

 but one species of bird. The first of tliese, encountered about 25 miles off Cape 

 Scott, B. C, on May 16, was the largest flock of whale-following birds that 

 I have ever seen, and was made up entirely of dark-bodied shearwaters. The 

 second flock, slightly smaller than the first, and seen off Yakutat, Alaska, on 

 May 25th, were, if my identification be correct, Leach's petrel. Both of these 

 flocks contained myriads of birds. They were visible fit a distance of three 

 or four miles and appeared as a dark cloud over the surface of the sea. As 

 the vessel approached nearer it was seen that not only was the air filled with 

 them but the water was supporting a still greater number. Their cries as 

 they flittered or swam about were deafening. In both instances schools of 

 about a dozen whales were being followed, and as they rose to the surface at 

 intervals to spout the birds would rush in that direction with movements that 

 bordered on a frenzy and with incessant screams. The fact that it seemed to 

 be the sole aim of the birds to keep as closely as possible to the school tended 

 to indicate that the whales were better able to locate the food supply. The 

 cetaceans appeared to do all the hunting; the birds simply trailed behind to 

 feed on what the former had found. .Just what type of marine animal life 

 serves to satisfy the tastes of both whale and bird is unknown to me, but it 

 is undoubtedly tiny fish, crustaceans, and the like. That the excretory matter 

 of the whale is also used by the birds is not improbable. The attraction, what- 

 ever it be, must remain very close to the surface of the sea, for it is readily 

 picked up by the latter, either when flitting along the water and when resting 

 on its surface. 



DISTRIBUTION. 



Breeding range. — Northern portions of the Atlantic Ocean. On 

 the American side, from the coast of Maine (Casco and Penobscot 



