BIRDS OF THE TRES MARIAS ISLANDS. 45 



Chordeiles acutipemiis texensis (Lawr.) Texas Nighthawk. 



A single specimen was taken May 5 on Maria Madre, and several 

 others were seen during the first half of the month, after which time 

 they disappeared. These birds were probably stray migrants, for there 

 was nothing to indicate that they were residents. 

 Amazilia graysoni Lawr. Grayson's Humming Bird. 



Amazilla f/raysoni Lawr., Ann. Lye. Nat. Hist., N. Y., VIII, p. 404, 1867. 

 Pyrrhopha-na yraysoni Grayson, Proc. Boston Soc. Nat. Hist., XIV, p. 283, 1871; 

 Lawr., Mem. Boston Soc. Nat. Hist., II, p. 292, 1874. 



Very common on the islands. They were seen almost everywhere 

 darting about the less luxuriant parts of the forest hunting for flowers, 

 and now and then stopping on a twig in some low tree top to rest or 

 arrange their plumage. They were among the numerous leathered 

 visitors to the little flower garden at the custom-house on Maria Madre 

 where they were very confiding, and would carry on their search for food 

 among the flowers quite indifferent to one's presence. These hum- 

 ming birds are very pugnacious, as the following incident recorded by 

 Colonel Grayson well illustrates : " Sometimes combats between them 

 become of a desperate nature. One day while watching a number of 

 them in active motion around some tobacco flowers (of which they seem 

 to be very fond) two fine males, after darting at each other for some 

 time, at length came to a deathly struggle, high above my head; they 

 finally clinched each other, each having one of the mandibles of the 

 other in his mouth, at the same time scratching with their little claws, 

 and using their wings with the greatest force, and in this situation, 

 whirling round and round, they fell to the ground near my feet. During 

 this terrible conflict, in which passion and desperation were exhibited, 

 I observed them for a few seconds and then gently placed my hat over 

 both. Even after they were thus captured, and I held one in each 

 hand, they evidenced a desire to continue the war." 



The same author records having seen these hummers dart upon and 

 capture little flies in the manner of a flycatcher, and found their crops 

 full of minute insects. This I can corroborate from my own observations. 



Upon comparing a series of 8 specimens of Amazilia graysoni with an 

 equal number of A. cinnamomea the general style of coloration is seen 

 to be very similiar, yet the differences between the two forms are so 

 constant it seems advisable to consider them specifically distinct. The 

 dorsal surface of A. graysoni is a more dingy green with less coppery 

 iridescence than in cinnamomea; the bronze tips of the tail feathers 

 are less uniform, and the extreme points sometimes terminate with a 

 little cinnamon spot; the cinnamon of the lower surface is considerably 

 darker. There is also a well marked and constant difference in size 

 graysoni being the larger, as shown by the following averages: 



