82 BULLETIN 121, UNITED STATES NATIONAL MUSEUM. 



tied, and in some cases the chin and fore breast. An extreme specimen is 

 sparsely spotted on the abdomen and posterior portion of the breast. Some 

 specimens display considerable white on the lower tail coverts." 



Mr. Anthony (18965) says that: 



A complete molt of all the feathers occurs in July and August in this species 

 and a more or less complete molt of the feathers of the head and body takes 

 place in .January and February. 



Food. — The principal food of the black-vented shearwater seems 

 to be small fish. Mr. John Treadwell Nichols writes me that he has 

 " found a mass of partially dio;ested, fine-boned fish in their stom- 

 achs." Mr. Anthony (1896&) writes: 



The presence of this species along the coast of Southern and Tiower Cali- 

 fornia seems to be governed very largely by the food .supply. They are common 

 at any time, less so during the breeding season, when many are in the burrows 

 during the day, and vastly more abundant in late July, August, and September, 

 when they follow the large schools of herring and other small fish that come 

 inshore at that season. 



They are often seen in flocks of several thousands where fish are plenty. 

 On one occasion I met with a flock on the coast of Lower California that 1 

 estimated contained not less than 50.000 shearwaters. Many were so gorged 

 with herring that they could not rise from the water, but flapped along the 

 surface in advance of the steamer until nearly overtaken, when they would dive. 

 They would usually come up near enough to the vessel to be, if anything, more 

 frightened than before, but could not take wing until they had disgorged a 

 quantity of half-digested fish, after which they flew off with apparent ease. 



On January 23 I was drifting in a skiff off Point Loma, watching the black- 

 vented shearwaters, which were flying south along the western edge of an 

 extensive bed of kelp. A garbage scow had sailed out through the kelp an 

 hour before, leaving a broad oily " slick " a hundred yards in width, extending 

 2 or 3 miles westward, at right angles to the course taken by the shearwaters, 

 which were passing in small flocks of four or five to a dozen every ten or 

 fifteen minutes. Each flock turned sharply about when at a distance of a 

 hundred yards from the oily water, and keeping at about that distance and 

 to the windward, hurried on toward the west. Not one bird did I see cross 

 contaminated water. I could detect no odor from the oil nor could the birds, 

 had any existed, for they were flying down the wind. 



I have never seen black-vented shearwaters pay any attention to bait or refuse 

 thrown from the ship's galley, though dark-bodied, pink-footed, and .slender- 

 billed shearwaters will light to pick up floating garl)iige. 



Though all of our shearwaters prefer to keep ratlier well offshore, they will 

 at times follow schools of small fish into shoal water. I once saw a flock of 

 one or two hundred black-vented shearwaters feeding in the surf at Cape 

 Colnett. Hovering over the advancing breaker, they followed it to the beach, 

 returning to meet the next, plunging repeatedly into its foamy crest for some 

 species of small fish. They evidently did not feel at home so near land, for 

 after a few miniites fishing they hurried out to sea again. 



Behavior. — In the same paper Mr. Anthony makes the following 

 observations on the flight of this species : 



It is only during very calm Aveather that this species is seen resting on the 

 Avater. At such times they collect in very compact flocks, covering the water 



