278 BULLETIN 121, UNITED STATES NATIONAL MUSEUM. 



on the other, completely surrounding them and forcing later arrivals of gulls 

 and pelicans to start other camp grounds farther along. These again are over- 

 taken and surrounded until by dusk the entire side of the island will be one 

 solid mass of closely packed birds, the white of the gulls and brown plumages 

 of the pelicans standing out in striking contrast to the inky blackness of the 

 cormorants, which form over three quarters of the mass. The species all flock 

 sepai-ately so far as is possible, and the result is a patchwork of white and 

 gray separated by broad zones of black ; even the Brandt and Farallon cormo- 

 rants roost apart, with the somewhat rare Baird cormorant still further re- 

 moved, perching on the low cliffs and rocks along the beach. Stragglers arrive 

 until late in the night ; the gulls in fact do not all get home until the first of 

 the early risers begin to leave at daybreak. The departure is even more grad- 

 ual if possible than the arrival of the night before, and it is not until the sun 

 is two hours high that the last of the cormorants leave for the fishing grounds. 



The following quotation from Mr. C. I. Clay (1911) will illus- 

 trate the remarkable diving ability of this species: 



We were one and one-half miles southwest from Trinidad, Humboldt County, 

 California, and about one-half mile off shore. Mr. Francisco had set a net the 

 night before near a blind rock and in twenty fathoms of water. We were 

 taking in the net when a Brandt cormorant came to the surface in its meshes, 

 then a second one and a third. Although the Baird cormorants were common 

 everywhere on the ocean there were none in the net. On closely questioning 

 the fisherman, he informed me Brandt cormorants were caught almost daily 

 in from five to thirty fathoms of water while using the deep water nets, but 

 were never taken in over forty fathoms of water, while the Baird cormorant 

 (I had taught him the difference between the two species) were often taken 

 in as much as eighty fathoms of water. 



I saw several Baird cormorants rise to the surface of the water with pieces 

 of kelp in their bills in places where Joe informed me the water was over 

 eighty fathoms deep. Brandt cormorants were not seen far offshore, though 

 they were common among the rocks near shore. Is it a superiority in diving 

 or a desire to obtain a certain kind of food that prompts the Baird cormorants 

 to go down deeper than Brandt cormorants while on their feeding grounds? 



DISTRIBUTION. 



Breeding range. — Pacific coast of North America. From extreme 

 southern British Columbia (Sidney Island, near Victoria) southward 

 all along the coast to extreme northern Mexico (Los Coronados 

 Islands) . Breeding grounds protected in the following reservations : 

 In Washington, Flattery Rocks, Quillayute Needles, and Copalis 

 Rock ; in Oregon, Three Arch Rocks ; and in California, Farallon. 



Winter range. — Includes most, if not all, of the breeding range 

 and extends southward to, at least, the central Mexican coast (Cape 

 San Lucas and Mazatlan). 



Egg dates. — California: Sixty records, May 3 to July 15; thirty 

 records. May 29 to June 19. Los Coronados Islands : Thirty records, 

 April 17. Washington and Oregon : Seven records, June 10 to 21. 



