492 BIRDS OF THE REPUBLIC OF PANAMA PART 3 



black ; rest of mandible dull whitish ; tarsus and toes fuscous ; claws 

 black. 



Measurements. — Males (10 from Canal Zone and western San 

 Bias), wing 59.5-64.6 (61.7), tail 56.2-60.8 (58.3), culmen from base 

 12.3-13.4 (13.0), tarsus 18.2-18.7 (18.3) mm. 



Females (10 from Canal Zone, eastern Colon and western San 

 Bias), wing 55.9-58.5 (57.0), tail 53.2-56.6 (54.8), culmen from 

 base 12.0-13.2 (12.5), tarsus 16.2-16.9 (16.5) mm. 



Weight of adult male 11.6 grams (R. S. Crossin). 



Resident. Locally common in Tropical Zone forests. Recorded on 

 the Pacific slope from eastern Chiriqui (San Felix) and Veraguas 

 eastward, through the Azuero Peninsula ; one record for Code (Nata, 

 December 28, 1888) ; appears again in the southern Canal Zone and 

 continues eastward through Darien to the Colombian boundary ; re- 

 corded at Cana on Cerro Pirre. On the Caribbean side, recorded in 

 Bocas del Toro (Almirante), northern Veraguas (Calovevora), 

 northern Code (El Uracillo), and western Colon on the Rio Indio, 

 east through the northern Canal Zone, the Chagres Valley, and 

 Comarca de San Bias to the Colombian boundary. 



As a species M. a. atricaudus seems more restricted in its distribu- 

 tion than M. s. aureatus, as it does not appear to range in mountain 

 areas above the lower foothills. Though not known at present in 

 western Chiriqui, it is possible that it may occur there as it is found 

 in southwestern Costa Rica. In Veraguas in 1953 I found it fairly 

 common from Zapotillo and Puerto Vidal east to the Rio San Pablo at 

 Sona. Aldrich collected it in 1932 on the Rio Mariato on the western 

 side of the Azuero Peninsula. On the eastern side and southern end 

 I secured specimens near Tonosi and Pedasi, Los Santos, and re- 

 corded it as common in Herrera. To the eastward it appears next in 

 the southern Canal Zone, and continues then through the Pacific slope 

 through eastern Darien. 



The Black-tailed Flycatcher is a bird of woodland cover, found in 

 the undergrowth of heavy stands of forest, but ranging also into more 

 open areas, even those of small extent. It also is found in second- 

 growth stands when these have increased beyond thicket size. Nor- 

 mally the birds flit through undergrowth and the lower treecrown as 

 actively as any warbler. Males display constantly by opening the 

 tail fanlike, and drooping the wings. And often they posture and 

 turn so that the somewhat fluffed yellow rump shows as a bright spot 

 of color. The display mainly is one of motion and contrasting color. 

 In it they are strongly suggestive of the Redstart, Setophaga ruticilla, 



