THE BIRDS OF NORTHERN THAILAND 427 



edges of the outer secondaries ashy white, to form a broad and con- 

 spicuous longitudinal bar in the folded wing; the rest of the upper 

 plumage, including the wings and tail, jet black; the underparts dull 

 black, washed with brown on the breast and belly, the feathers of the 

 abdomen narrowly fringed with ashy, the under tail coverts more 

 broadly margined with ashy white. The adult female differs in 

 having the general coloration olivaceous-brown, with the wing mark- 

 ings dull rufous. 



TURDUS OBSCURUS Gmelin 



White-browed Thrush 



[Turdus] obscurus Gmelin, Systema naturae, vol. 1, pt. 2, 1789, p. 816 ("in 



Sibiriae silvis, ultra lacum Baical"). 

 Turdus obscurus obscurus, Deignan, Journ. Siam Soc. Nat. Hist. Suppl., 1931, p. 



143 (Doi Suthep). — Chasen and Boden Kloss, Journ. Siam Soc. Nat. Hist. 



Suppl., 1932, p. 245 (Doi Suthep). — de Schauensee, Proc. Acad. Nat. Sci. 



Philadelphia, 1934, p. 211 (Khun Tan, Doi Suthep, Doi Chiang Dao).— 



Riley, U. S. Nat. Mus. Bull. 172, 193S, p. 410 (Doi Ang Ka, Doi Langka).— 



Greenway, Bull. Mus. Conip. Zool., 1940, p. 180 (Doi Ang Ka). 

 Turdus obscurus, Deignan, Journ. Siam Soc. Nat. Hist. Suppl., 1936, p. 112 



(Doi Suthep). 



Smith took a specimen of the white-browed thrush on Doi Ang Ka, 

 8,000 feet, December 5, 1928, but all other northern records have been 

 made betwen January 3 (Khun Tan) and April 18 (Phu Kha). So 

 common a migrant is this bird in March and April (when hundreds 

 may sometimes be seen in a single day) that its rarity or absence dur- 

 ing the autumn months can only be explained by assuming that its 

 southbound passage follows some other route. It is a species of the 

 more open evergreen and occurs in suitable territory from the level of 

 the plains (1,214 feet at Chiang Eai) to the summits of the highest 

 hills (8,400 feet on Doi Ang Ka). 



I found it usually in large, loose flocks, feeding quietly on the ground 

 beneath the ferns or in low berry-bearing trees. It is excessively shy 

 and, at the slightest alarm, takes refuge in the tops of the highest 

 trees at hand. 



Two males had the irides brown ; the maxilla blackish brown, with 

 the edges of the commissure yellow on the basal half; the mandible 

 yellow, with the tip blackish brown; the rictus and interior of the 

 mouth yellow; the feet, toes, and soles yellow; the claws pinkish horn 

 or light brown. 



The adult male has the entire upperparts, including the wings and 

 tail, olivaceous-brown, the forehead, crown, and nape more or less 

 strongly suffused with ashy ; the supercilium white ; the lores black ; a 

 patch beneath the e}^e and another below the lores white; the chin 

 white, edged at each side by a short, indistinct black mustachial streak ; 



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