MONOGRAPH OF THE PETRELS. 



Columbia River in November. Mr. Ridgway, writing in 1884 (Water-Birds N. Amer., 

 II., p. 389), believed that it occurred along the entire Pacific coast, as far north, at least, 

 as Oregon. 



Mr. Anthony further remarks (I.e.) that, although Major Bendire informed him that 

 there were two or three eggs in the U. S. National Museum, said to have been taken on 

 one of the Santa Barbara Islands, he doubted the fact, as the larger islands were so 

 infested with foxes that the birds would have been exterminated ; they might, however, 

 possibly breed on some of the smaller islands where these animals did not exist, and 

 Mr. Grinnell confirms this view. Mr. Anthony also states that the Black-vented 

 Shearwater is not met with until the island of Guadalupe is reached, about 200 miles 

 south of the United States boundary, where he found it breeding plentifully. On the 

 San Benito Islands, lying between Guadalupe and the Cerros Islands, a few pairs were 

 nesting, whilst in August on Natividad Island, about 35 miles south of San Benito, the 

 birds returned in thousands to roost. Numerous fresh tracks were observed outside 

 the burrows, showing the imprint of the tarsus for its full length, from which it was 

 evident that the birds placed their weight on the tarsus as well as on the toes. 



To Mr. Anthony we are also indebted for an account of the nesting of P. opisthomelas. 

 In Guadalupe the burrows were dug under huge blocks of lava, but on the San Benito 

 Islands the nests were situated in small caves, which were nearly filled with deposits of 

 guano, the accumulation of years. The nests were inaccessible, but every cave appeared 

 to have been inhabited by several pairs of birds, judging from the outcry and warning 

 hisses made when the entrance was approached. When revisiting Natividad Island 

 on the 10th of April, 1897, each burrow was tenanted by a pair of Shearwaters, or a 

 single bird with its egg. The burrows were seldom straight, usually 10 feet long, and 

 only about 18 inches below the surface of the ground. The egg was either placed on a 

 rude structure of a nest, or in a slight depression, at various distances between the 

 entrance and the end of the hole. Eggs from Natividad Island are white, and measure : 

 Axis, 2.25-2,8 inches ; diam., 1.6-1.65. 



Adult male. General colour above sooty-brown, faintly mottled on the mantle 

 and hind-neck, but less so on the rest of the upper-surface, the feathers of the back 

 being more or less white at the base, and having an indistinct edging of ashy-grey ; 

 the lower back, rump, and upper tail-coverts uniformly black, with obsolete ashy 

 margins ; wing-coverts, scapulars, and innermost secondaries like the back ; the 

 primary-coverts and quills black, with narrow fringes of ashy-white at the ends of the 

 latter ; tail-feathers black ; head sooty-brown, like the back, and not contrasting with 

 the latter ; lores and sides of face like the crown, slightly mottled with white ; below 

 the eye a small white mark ; under-surface of body pure white, but mottled with ashy- 

 brown on the cheeks, and on the sides of the throat and chest, where the brown back 

 and white under-surface meet ; these brown mottlings broken up on the sides of the 

 lower throat, and extending nearly across the latter ; the sides of the lower flanks 



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