FAMILY FALCONIDAE 275 



indistinctly with grayish white; lower rump mixed buffy white and 

 fuscous-black, with a few irregular spots of the latter color on the 

 central feathers of the buffy upper tail coverts ; tail barred with buff 

 and brownish gray to black, the dark bands equal in width to the 

 pale ones, with a broad subterminal band of fuscous-black, and a 

 narrow tip of white ; under surface of wing buffy white, barred nar- 

 rowly, and tipped broadly with brownish black. 



Immature, with head, neck all around, breast, and sides streaked 

 with fuscous ; under wing coverts barred with the same color ; tip of 

 tail banded like the central portion. 



Measurements. — Males (8 from Panama), wing 265-287 (278), 

 tail 177-201 (188), culmen from cere 21.5-23.5 (22.6), tarsus 50.4- 

 54.2 (51.8) mm. 



Females (4 from Panama), wing 272-288 (282), tail 183-198 

 (189), culmen from cere 21.7-24.1 (22.7, average of 3), tarsus 

 51.0-52.2 (51.3) mm. 



Resident. Fairly common in the tropical lowlands of the Pacific 

 slope, from western Chiriqui (Alanje) east to the lower Rio Bayano 

 (El Llano), including the Azuero Peninsula, and the Archipielago de 

 las Perlas (reported from Pacheca, Saboga, Rey, Canas, Viveros, La 

 Vivienda, Pedro Gonzalez, Trapiche, and San Jose islands) ; ranging 

 upward to 600 meters in western Chiriqui (Buena Vista above 

 Concepcion). 



These are birds of savanna lands bordered by trees and open 

 scrub, that are not found in the more humid Caribbean lowlands 

 or in Darien. As the forests are cleared they spread to some degree 

 through country formerly not suited to them. In January 1961 I 

 saw one at Gatuncillo on the Rio Chagres between Juan Mina and 

 the dam. They are found constantly feeding on the ground around 

 cattle and often fly up to perch on the backs of grazing or resting 

 beasts, where ordinarily their great companions pay no attention to 

 them. On occasion I have seen one fluffing and arranging its feathers 

 as it sat on the hip bone of a cow at rest on the ground. At La 

 Jagua one early morning one alighted on the back of a resting bull 

 where it moved along to its head in search of ticks, particularly 

 around its ears. Later other bulls were less complaisant, for when 

 two birds came they switched their tails and moved their heads to 

 drive the hawks away. 



The flight is direct but not swift, divided between flapping and 

 sailing, and seems rather weak for a bird of this family. They are 

 scavengers to some degree, and in addition eat such small animal 

 prey as is available — large insects, small birds (including young), 



