142 



BIRDS OF THE REPUBLIC OF PANAMA PART 4 



TURDUS NIGRESCENS Cabanis: Sooty Robin, Casca Tiznada 



T urdus nigrescens Cabanis, Journ. fur Ornith., vol. 8, no. 47, "September, 1860," 

 published January 1861, p. 234. (Volcan Irazu, Costa Rica.) 



Large; adult blackish brown; bill and feet yellow. 



Description. — Length 235-270 mm. Adult male, dull grayish brown 

 to blackish brown; wings and underwing coverts dull black; lores and 

 area around eye black; throat indistinctly lined with black. 



Adult female, similar to male in general, but duller; throat faintly 

 paler, with black lines more distinct. 



Immature, averaging lighter on dorsal surface; crown, back, and 

 scapulars streaked with dull buff; greater and middle wing coverts 

 tipped narrowly with dull buff to form somewhat indistinct bars; under- 

 surface basally dull ochraceous-buff, with the individual feathers tipped 

 and barred with dull black; dull buff of throat only lightly marked; 

 undertail coverts blacker, narrowly lined with buff; underwing coverts 

 dull blackish brown, barred and edged with dull cinnamon-buff. 



In an adult female, taken March 1, 1965, at 2300 m on the west face 

 of Volcan de Chiriqui, the iris was ivory-white; bill bright yellow, 

 with a faint clouding of dull brown on the nasal operculum, and on the 

 side of the culmen adjacent; tarsus and toes bright yellow; claws black; 

 bare, thickened outer rim of eyelid honey yellow. Some specimens of 

 either sex have the entire bill plain yellow. 



Measurements. — Males (10 from 1900 to 3100 m on Volcan de 

 Chiriqui), wing 137.5-144.9 (140.9), tail 107.3-119.4 (114.2), culmen 

 from base 23.6-26.1 (24.9), tarsus 37.0-39.3 (37.8) mm. 



Females (10 from 1920 to 3100 m on Volcan de Chiriqui), wing 

 134.8-138.9 (137.6), tail 107.2-114.2 (110.4), culmen from base 23.5- 

 25.0 (24.4), tail 35.1-38.4 (36.5) mm. 



A series from Costa Rica agrees in size with the measurements 

 above. 



Resident on the higher levels of Volcan de Chiriqui, Chiriqui, at 

 1800 to 3000 m, also occurs lower on the Volcan de Chiriqui massif, and 

 in the high mountains of Costa Rica. 



The little that is known of these mountain thrushes indicates them 

 usually to be tame, ranging among trees and also on the ground, alone 

 or in scattered company of a few individuals, frequently in pastures 

 and clearings. The species, described from Volcan Irazu in Costa 

 Rica, was first recorded from Panama by Salvin and Godman (Biol. 

 Centr. Amer., Aves, vol. 1, 1879, plate 1, p. 25) from several specimens 

 sent to them by Enrique Arce marked "Volcan de Chiriqui." Bangs 

 (Proc. New England Zool. Club, vol. 3, 1902, p. 49) recorded a series 



