LIFE HISTORIES OF NORTH AMERICAN PETRELS AND PELICANS. 153 



The mortality among these birds from the depredatious of the cats that 

 overrun the island is appalling — wings and feathers lie scattered in every 

 direction around the burrow^s along the top of the pine ridge. The species, how- 

 ever, is stiU breeding in large numbers in Guadalupe, and sometimes at night 

 the air seemed to be fairly alive with petrels, their peculiar cries being heard 

 on all sides. 



Eggs. — The Guadalupe petrel lays but one egg, which in shape is 

 between oval aild elliptical oval. The shell is thin and smooth, but 

 lusterless. When fii*st laid it is pure, dull white, with a wreath of 

 minute spots, of a faint reddish brown color and lavender about 

 the larger end ; some specimens have fine dots of pale lavender mixed 

 with the reddish spots. After the egg has been incubated for a few 

 days it becomes so nest stained that the original color and the spots 

 are entirely obliterated. An egg in my collection is deeply stained, 

 over all of its surface, an uneven reddish brown color, with accumu- 

 lations of soil caked onto it in places. 



The measurements of 50 eggs, in various collections, average 35.7 

 by 27 millimeters; the eggs showing the four extremes measure 38 

 by 27.5, 36 by 29, 31.5 by 26, and 33 by 24 millimeters. 



Young. — The downy young is covered with long, soft, thick down 

 of a "Benzo brown" or "light drab" color. Apparently the young 

 bird molts directly from the downy stage into a plumage resembling 

 the adult. 



Behavior. — In its flight and behavior the Guadalupe petrel closely 

 resembles the other species of the genus Oceanodroma from which 

 it probably does not differ very much in habits. On account of its 

 close resemblance to other species very little has been published re- 

 garding its habits except on its breeding grounds. 



DISTRIBUTION. 



Breeding range. — Known to breed only on Guadalupe Island, off 

 the Pacific coast of Lower California. 



Range. — So far as known, only in the vicinity of Guadalupe 

 Island. 



Egg dates. — Guadalupe Island: Twenty-two records, March 4 to 

 July 2 ; eleven records, March 24 and 25. 



OCEANODROMA CASTRO (Harcourt). 

 HAWAIIAN PETREL. 



HABITS. 



Although merely a rare straggler in North America, this petrel 

 enjoys a wide distribution in the Atlantic and Pacific Oceans as far 

 north as Madeira in the former and the Hawaiian Islands in the 

 latter. 



