1871.] 301 [Grayson. 



FALCONID^. 



9. Buteo borealis var. montanus Nutt. "Western Red Tailed 

 Hawk." 



"This is the only hawk found upon the island, and here it is quite 

 common, being a constant resident, rearing its young, and subsisting 

 exclusively upon land crabs, which they find in great abundance, 

 and an easy prey. Their claws are much blunted, doubtless caused 

 by the frequent contact with the hard shell of these Crustacea. This, 

 and the night heron, ar,e the only large landbirds found upon the 

 Socorro Island." 



ARDEID.2E. 



10. NyctherodiusviolaceuS(Linn.). "Yellow-crowned Night 

 Heron." 



"Upon this remote island, where there is a scarcity of fresh water, 

 I was surprised to find this well-known species. Here its natural 

 haunts.are entirely wanting. Here there are no lagoons or man- 

 grove swamps to skulk in during the day ; and the croaking of frogs, 

 its favorite prey, is not heard. All is dry, and destitute of such lo- 

 calities suited to the nature of fresh water birds. I saw solitary ones 

 in the day time perched upon the rocks in the interior of the island, 

 and on one or two occasions, were started from the dry grass, where 

 they were concealed. Hardly a night passed that I did not hear the 

 well-known quak of this heron, as they came to our spring to drink. 



"From the appearance of the male bird on examination, and the 

 presence of the young one shot, they doubtless breed here to some 

 extent. Feed entirely upon crabs." 



LARIDiE/ 



11. Haliplana fuliginosa var. erissalis Baird. "Black Billed 

 Tern." 



"Remarks. This tern is very numerous in the vicinity of the 

 Tres Marias, and the little Island of Isabella, near San Bias, upon 

 which they breed. About the Revillagigedo group they are only 

 scattering, and replaced by another species — a black tern with a hoary 

 forehead, which are quite numerous in this locality. Although I shot 

 some of these from the deck of our vessel, yet I was unable to pro- 

 cure a single specimen ; because the sea was too rough to launch our 

 frail little skiff.- I shot many other sea birds which I was unable to 



