SHORT-TAILED HAWK 257 



granulated and without gloss. The ground color is pale bluish white 

 in the unmarked eggs, or dull, dirty white in the heavily marked 

 eggs. Some eggs are immaculate or show only a few scattered, mi- 

 nute dots or scrawls of pale buff, or a few scattered brown spots. 

 Some are irregularly spotted and some heavily blotched, about one 

 end or the other, with dark browns, "Vandyke brown" or "warm 

 sepia." One set is extensively washed with "tawny" and spotted 

 with "chestnut-brown." The measurements of 27 eggs average 53.4 

 by 42.8 millimeters; the eggs showing the four extremes measure 

 57.5 by 40.9, 53 by 45.5, 48.6 by 41.8, and 49.2 by 40.3 millimeters. 



Plumages. — The young found in the nest by Mr. Nicholson 

 (Brandt, 1924) were "in white down." I have seen no nestlings. 

 In Juvenal plumage the upper parts are brownish black, mixed with 

 "light ochraceous-buff" on the head and neck; the feathers of the 

 scapulars, wing coverts, and upper tail coverts are edged with 

 "tawny"; the tail is blackish brown above and silvery gray below, 

 crossed by 9 or 10 bars of black above and dark gray below; the 

 under parts are white, strongly tinged with "light ochraceous-buff." 

 I have seen birds in this plumage in November and in April, taken 

 in Venezuela. Other birds, taken there in June and October, are 

 similar, but the upper parts are clear brownish black, without tawny 

 edgings; these may be older birds, but they still have juvenal tails; 

 in the adult tail there are about half as many bars and these are 

 broken or incomplete, except the broad subterminal bar. Another 

 immature bird, collected in Venezuela in August, is dark brown 

 above, without edgings, and white below, streaked on the sides of 

 the neck and breast and heavily spotted on the flanks and belly with 

 blackish brown. Some birds in the black phase show more or less 

 white in the under parts; these are probably immature. The two 

 striking color phases of adults are too well known to need any de- 

 scription here, but one of Robert Ridgway's (1881b) early papers on 

 this subject is instructive. 



Food. — Very little has been published about the food of the short- 

 tailed hawk. One that Harold H. Bailey (1925) had in captivity 

 "ate readily of hamburger steak, small bits of meat, mice and rats." 

 Mr. Howell (1932) says that a stomach "examined in the Biological 

 Survey contained the feet and other remains of a Sharp-shinned 

 Hawk." Probably snakes, frogs, lizards, small mammals, and small 

 birds are also eaten. 



Behavior'. — Mr. Brandt (1924) has this to say about behavior and 

 voice : 



As we approached the tree the male, a bird in the black phase, flew up and 

 circled above, uttering a few cackling notes, somewhat like the Red-shouldered 

 Hawk. This was heard but once. When we struck the tree the female, a 



