84 



BIRDS OF THE REPUBLIC OF PANAMA PART 4 



rufescent on the undertail coverts and duller on the sides; axillars and 

 underwing coverts dull white, mixed indistinctly with dusky. Young 

 birds have the throat buffy with the dark lines very indistinct. 



A male taken at Armila, San Bias, February 26, 1963, had the iris 

 auburn, narrow cutting edge of maxilla dull white; rest of maxilla 

 black; mandible dark neutral gray on sides, neutral gray on lower sur- 

 face; tarsus and toes fuscous-brown; claws dark neutral gray. An- 

 other male at this locality, March 2, 1963, had the iris orange; tarsus 

 and toes brownish neutral gray. 



Measurements. — Males (10 from San Bias and Darien) wing 55.4- 

 58.0 (56.7), tail 34.3-39.7 (37.1), oilmen from base 17.5-19.3 (18.5), 

 tarsus 18.0-21.7 (20.4) mm. 



Females (6 from eastern Province of Panama, San Bias, and Da- 

 rien), wing 51.6-56.2 (53.1), tail 34.4-36.2 (35.3, average of 4), culmen 

 from base 17.3-19.3 (17.9, average of 5), tarsus 18.6-20.2 (19.3) mm. 



Resident. Found locally in eastern Panama; on the Caribbean slope 

 in eastern San Bias from Perme and Armila to the Colombian boundary 

 at Puerto Obaldia; on the Pacific side, from Cerro Chucanti, at the head 

 of Rio Maje, in extreme eastern Province of Panama, and Darien (re- 

 corded at Tapalisa, Cituro, Pucro, and at the base of Cerro Quia (Rio 

 Mono) in the upper Tuira Valley, and near Cana, on Cerro Pirre; near 

 Jaque and on the upper Rio Jaque) . Outside of Panama, this species is 

 found in western Colombia and northwestern Eucador. 



These wrens range more in the open than most of their relatives. 

 While they may be found low down, in dense growth near the ground, 

 they also are regularly seen higher, among vines and branches in forest 

 areas. The only one seen on Cerro Chucanti associated with a group of 

 small ant-wrens in the lower branches of open forest. One near Armila 

 hunted through the higher limbs in a cacao plantation, and another on 

 the Rio Pucro was in open cover near a trail leading through a forest. 

 On the Rio Jaque, 1 searched through a mass of vines 10 m above the 

 ground, and at Jaque I found 1 in the undergrowth in heavy forest. At 

 other localities I saw them regularly in fairly open areas at heights of 

 15 to 18 m. 



At Armila, on March 2, 1963, a pair was busily building a nest in 

 fairly open forest at the border of a quebrada. The structure was an 

 untidy ball, irregular in form, placed near the end of small branches 

 with no attempt at concealment. 



Hellmayr (Cat. Birds Amer., pt. 7, 1934, p. 176), with a rather small 

 series, listed the Thryothorus leucopogon group as a geographic race 

 of the widely separated T. thoracicus, a treatment that has been ac- 



