i62 Natural History of the Faralloncs. [zoe 



siderable convenience in the social intercourse of the parent birds. 

 It is a significant fact that the patch is white, as with the markings 

 about the head in so many mammals that live in burrows. There 

 is, however, another use in this white patch of the sea parrot. I 

 noticed that the setting bird always faced the entrance to her re- 

 treat, exposing the white patch in full view. On seeing this special 

 precautions were used in inserting the hand to prevent being bitten, 

 for the bite of a puffin is a dangerous thing. It is quite evident that 

 this white patch must serve as a warning for intruders to keep off, 

 and is one of the few cases of warning colors among birds which 

 have come to my notice. 



A series of the young of Cassin's auklet was obtained, but the 

 bird is nocturnal in habits so that very little was seen of the adult. 

 Figure 3 of Plate xxi shows the young puffin's head, the bill, even 

 at this early stage of development being greatly enlarged and trans- 

 versely grooved. The bird is feathered when hatched, apparently, 

 at least the youngest specimen obtained was completely so, and of 

 a dark brown color. Figure 5 shows the head of Cassin's auklet. 

 It may be recognized at the earliest age obtainable by the little up- 

 turned snub bill and the gray feet. 



In size and general color the young of the pigeon guillemot is 

 not unlike the young of Cassin's auklet, both being dark-brown in 

 color; but the difference in the shape of the bill, as shown in Fig- 

 ure 4 of Plate xxi, is very marked, as is also the character of the 

 feet. The throat of the guillemot is feathered, while in the auklet 

 it is almost naked, and of a dark slaty color. 



Mr. Anthony noticed Cassin's auklets nesting along the sides of 

 one of the caves which he explored, which is quite an unusual habit 

 with this species. I noticed that they also nest on level ground in 

 crannies under loose rocks. At night, especially if the moon is up, 

 the birds are very abundant and noisy. Their note resembles the 

 creeking of a rusty gate, and may be represented by the syllables 

 creek a reek! creek a reek/ creek a reek! Another nocturnal bird is 

 the ash)- petrel ( Oceanodroma homochroa). It is perhaps not so rare 

 upon the island as it is difficult to find. Mr. Anthony obtained a 

 large number of eggs and birds by systematically turning over rocks 

 on a hillside where they were known to be found. The nest is fre- 

 cjuently, though by no means invariably, indicated by the strong 

 musky odor in its vicinity. The flight of the petrel was light, quick 



