94 



BIRDS OF THE REPUBLIC OF PANAMA PART 4 



cember to September. Skutch found that grown young accompanied 

 their parents for several months. On April 20-21, 1968, C. Leek and S. 

 Hilty netted birds near the road to El Volcan at ca. 1140 m (confirmed 

 by color slide) . Eisenmann saw a pair engaged in antiphonal singing at 

 Buena Vista (690 m) in a thicket of a boggy area on March 4, 1960. It 

 ranges to the west in southwestern Costa Rica from the lowlands to 

 about 900 m elevation. 



The close relationship of T. semibadius to the diverse forms of Thry- 

 othorus nigricapillus is clearly evident, but the former differs definitely 

 and completely from them in always having the crown chestnut-brown 

 like the back, and also in the narrow bars on the lower surface which 

 are produced by three black bands on each feather, instead of two bands 

 as in the races of nigricapillus that have this marking. ( For other brief 

 comment see Wetmore, Smiths. Misc. Coll., vol. 139, no. 2, 1959, p. 17) . 

 Hellmayr (Cat. Birds Amer, Field Mus. Nat. Hist., pt. 7, 1934, p. 180) 

 listed semibadius as a subspecies of nigricapillus, a treatment accepted 

 also by Paynter (Check-List Birds World, vol. 9, 1960, p. 407), but 

 one that does not seem justified, as there is no indication whatever of an 

 approach in the markings described above that separate the two. 



THRYOTHORUS ATROGULARIS Salvin. Black-throated Wren, 

 Cucarachero Gargantinegro 



Thryothorus atrogularis Salvin, Proc. Zool. Soc. London, February 1865, p. 580. 

 (Tucurrique, Costa Rica.) 



Medium size; deep chestnut-brown; side of head, throat, and upper 

 breast black. 



Description. — Length 145-160 mm. Adult (sexes alike) ; upper sur- 

 face, from forehead to upper tail coverts, including scapulars and outer 

 webs of wings, chestnut-brown; concealed webs of wings dusky; upper 

 tail coverts barred lightly with black; tail black, with indefinite, partly 

 concealed brownish bars; side of head to auricular region, chin, fore- 

 neck, and upper breast black; superciliary, auricular, and nasal area 

 spotted and lined lightly with white. 



Immature, without black on forepart of body, side of head, and un- 

 dertail coverts. 



Bill dull black; iris brown, tarsus black. In juvenile, mandible ex- 

 cept tip yellowish. 



Measurements. — Males (10 from Bocas del Toro), wing 65.0-68.6 

 (66.8), tail 51.4-54.7 (53.2), culmen from base 19.5-22.0 (20.8), tarsus 

 21.5-25.5 (24.4) mm. 



