FAMILY TYRANNIDAE 375 



western Louisiana to southern Texas, northern Nuevo Leon, and 

 northern Tamauhpas. It is known in winter from southern Mexico 

 (and sparingly in southern Florida) south to western Panama. 



MUSCIVORA TYRANNUS MONACHUS (Hartlaub) : Fork-tailed 

 Flycatcher, Tijereta Sabanera 



Figure 35 



Tyrannus (Mihulus) innnaclnts Hartlaub, Rev. Zool., vol. 7, June 1844, p. 214. 

 (Guatemala). 



Medium size ; with very long, slender tail ; crown and tail black. 



Description. — Length 240-360 mm. Outer rectrix decidedly longer 

 than the one adjacent. Adult male, three outer primaries incised at 

 tip ; crown, hindneck, and sides of head black ; a large, concealed 

 yellow area bordered with white in center of crown ; back and scapu- 

 lars light gray, becoming darker on the upper rump ; lower rump and 

 upper tail coverts dusky to black ; wings dark gray, with the coverts 

 and flight feathers edged in varying amount with white to light gray ; 

 tail black, the outer rectrix white on the narrow outer web for half 

 or less of length ; under surface, including malar region, axillars, and 

 under wing coverts (except the outermost) pure white; posterior 

 outer under wing coverts gray. 



Adult female, tips of outer primaries not incised; coloration as in 

 male, but tail shorter. 



Juvenile, head grayish to sooty brown ; back somewhat brownish 

 gray; rump, and wing coverts, in part, edged with buff to cinnamon- 

 buff ; outer rectrix edged with white as in adult ; others tipped and 

 edged lightly with cinnamon to cinnamon-rufous. 



In two adult females, taken January 11 and March 9, 1962, the 

 iris was dark reddish brown ; bill, tarsus, toes, and claws black. 



Measurements. — Males (10 from Chiriqui, Los Santos, Herrera, 

 and Province of Panama), wing 102.4-107.2 (103.5), tail 232.0- 

 284.0 (254.0), culmen from base 17.1-18.3 (17.8), tarsus 17.0-17.8 

 (17.3) mm. 



Females (10 from Chiriqui, Herrera, Code, Panama, and Costa 

 Rica), wing 94.0-100.8 (95.9), tail 137.0-195.0 (173.0), culmen from 

 base 17.1-18.3 (17.6), tarsus 17.0-17.5 (17.2) mm. 



Found throughout the year. Common locally on the savannas and 

 other open areas of the Pacific slope, from western Chiriqui (where 

 it is encountered from the coastal lowlands to the open Llanos del 

 Volcan, to 1460 meters on the western base of Volcan F)arii), east 

 through southern Veraguas, the eastern side of the Azuero Peninsula, 



