NO. 2298. 



THE GUANO BIRDS OF PERV—COKER. 



479 



slanting aerial trolley wires or on the low rocks near the shore. They 

 remain generally motionless, though grunting noisily, but occasionally 

 fly down into the water to dive for fish. They seem to prefer the 

 bottom fish or shallow-water fish close in shore, such as the "tram- 

 boUos" (blennies), which one may see from the rocks in almost any 

 suitable place. The cuervo can swallow fish of considerable size, and 

 I have found in the stomachs tramboUo fish from 2^ to about 10 

 inches in length. 



The nesting places were observed only at the Lobos de Tierra 

 Islands in the north in midsummer — December, 1907. It is not 

 doubted, however, that a visit to the southern islands at the same 

 season would have revealed nesting places in that locality. The 

 choice of nesting site is characteristic and is well shown in the illus- 

 tration (pi. 64). They were using small rough-topped rocks lying 

 close along the shore, but partly or entirely cut off from the shore 

 proper. 



The nests contained from one to five eggs or young, usually four 

 eggs or four young birds. The eggs are comparatively small and pale 

 blue in color, the blue somewhat obscured by a chalky coating which 

 is not uniformly disposed. They were variable in shape. Four eggs 

 from one nest were of an ordinary oval form, 53 by 36 mm., and these 

 were representative of most of the eggs observed ; one nest, however, 

 contained five greatly elongated eggs. The nestlings were black. 



Dimensions, in millimeters, of the eggs of the *^ Cuervo de Mar.^' 



1 



2 

 3 



4 



Long 

 diameter. 



Transverse diameter. 



og [characteristic form. 



5 

 6 



7 



Long 

 diameter. 



Transverse diameter. 



I Unusual form; 5 eggs 

 I from one nest. 



As compared with the guanay, the tail of the cuervo is rather 

 long, the bill rather short, and the bird is lighter in build. Its weight, 

 about 3i pounds, is a fourth less than that of the guanay. The 

 iris is green in both species. 



The cuervo ranges probably the entire length of the Peruvian 

 coast from Tumbes in the north to Chile, and it extends to the inland 

 waters. 



The cuervo de mar is excellently described by Taczanowski.* It 

 must be remarked that in the specimens from which my color notes 

 were made (Lobos de Afuera, November and December, 1907), the 

 white feathers on each side of the auricular region, as described by 



> Omithologie, vol. 3, pp. 429, 430. 



