The Leach Petrels 



on exposed wing-quills and tail; browner, deep chocolate brown, on belly; paler, more 

 ashy brown on face; an area formed by middle and greater wing-coverts and portion 

 of tertials much lighter, drab, the tips of greater coverts still paler, nearly whitish; 

 the lateral upper tail-coverts, and sometimes the entire rump, more or less extensively 

 white (this character very variable). Bill and feet jet black. Length 203 (8.00) or 

 under; av. of 3 spec, from Los Coronados Ids. (skins); 192 (7.56); wing 155 (6.10); 

 tail 78 (3.07); depth at fork 21.2 (.83); bill 15.5 (.61), depth at base 6.2 (.24); tarsus 

 22.4 (.88). 



Recognition Marks. — A middle-sized petrel, larger and darker than homo- 

 chroa, smaller and a little lighter than melania, from both of which it is usually dis- 

 tinguishable by the presence of white on the sides of rump. This is really a localized 

 representative of the leucorhoa group, embracing the Pacific species, beali, kcedingi, 

 socorroensis, macrodactyla (enumerating from north to south), monorhis of China, and 

 castro of the southern oceans; it is distinguishable from beali of the north coast by its 

 paler wing-coverts and the lateral white patches not meeting, or at least less extensively 

 meeting, across rump. 



Nesting. — Much as in 0. 1. beali. Av. size of 15 eggs in M. C. O. coll.: 29.85 

 x 22.35 ( I - I 75 x -88); index 74.9. Season: Late June or early July. 



Range of 0. I. socorroensis. — Breeds on Los Coronados Islands, just south of 

 the Mexican boundary line, and San Benito Island, further down the Lower California 

 coast. According to A. W. Anthony, it is fairly common in summer on the ocean off 

 San Diego. 



Authorities. — Anthony (Oceanodroma socorroensis), Auk, vol. xii., 1895, p. 387 

 (ocean, off San Diego); Howell, Pac. Coast Avifauna, no. 12, 1917, p. 35 (s. Calif, ids.; 

 habits, syst.; crit.) ; Loomis, Proc. Calif. Acad. Sci., ser. 4, vol. ii., pt. 2, no. 12, 1918, 

 p. 160, part (syst.; crit.). 



A GREAT FORBEARANCE, whether wise or no we shall not under- 

 take to say, has for decades kept the Yankee out of Lower California. Its 

 teeming lagoons and alluring wildernesses have now and then resounded 

 to the crackle of revolutionary rifle-fire, but the white man has for the most 

 part kept a prudent distance. The political conquest of this portion of 

 Mexico has made small headway or none at all in a century, but, more 

 fortunately, a scientific conquest of the islands off the west coast has been 

 made under such leaders as C. H. Townsend, A. W. Anthony, Walter E. 

 Bryant; and, more recently, George Willett, Howard W. Wright, and A. B. 

 Howell. "Fortunately"; for with the advent of Mexican shepherds or 

 fishermen to these islands came rats or cats or other vermin, which, lacking 

 the controlling factors of mainland conditions, have nearly done for much 

 of the native feathered life. The Island of Guadalupe has been the chief 

 sufferer; and this devoted spot now boasts no less than five "extinct" or 

 extirpated species. 



The case of Guadalupe is hopeless, and all scientists are left to mourn ; 

 but by common consent the islands called Los Coronados, lying off San 

 Diego within Mexican waters, are a sort of classical resort (not to say 

 plunder-box) for American ornithologists; and the ultimate welfare of the 



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