142 BIRDS OF THE REPUBLIC OF PANAMA PART 3 



bound with cobweb to its supports, with a few bits of green moss 

 on the outside. Six nests ranged from about half a meter to over 

 3^ meters above the ground. The two eggs in the normal set "are 

 dull white, with a wreath of bright brown and pale lilac blotches 

 and spots around the large end and a few speckles scattered else- 

 where." Two eggs in one set measured 23.8 X 16.7 and 22.2 X 16.7 mm. 

 Both parents incubate, but only the female through the night. The 

 incubation period ranged from 14 to 15 days. Young at hatching 

 were without down. The male continues to aid in feeding the young. 



In the Burica Peninsula, where the Barred Ant-shrike was rare, I 

 believed that it might be competitive with the present species, but in 

 the coastal area below Las Lajas, near Playa Jobo, the two seemed 

 to be compatible, where their habitats met. The Black Ant-shrike, 

 however, ranged in the forest undergrowth, while the other was 

 mainly in the more open thickets and forest edge outside. 



Cabanis (Journ. f. Orn., 1861, pp. 241-242) who received a male 

 from Hofifmann, taken in Costa Rica, described it as Thamnophilus 

 punctatus, for apparently he was not aware of Sclater's earlier name. 

 He also proposed to place it in a separate genus Ahalins, because of 

 its slightly less prominent crest. This separation was used also by 

 Ridgway (U.S. Nat. Mus. Bull. 50, pt. 5, 1911, pp. 24-25) but on 

 more detailed study is not justified. Beyond Chiriqui, Slud (Bull. 

 Amer. Mus. Nat. Hist., vol. 128, 1964, p. 212) found Thamnophilus 

 hridgesi common in the Pacific lowlands of southwestern Costa Rica, 

 ranging north to the head of the Gulf of Nicoya. He reports it 

 "at lower subtropical elevations along the humid continental divide 

 in the vicinity of Lake Arenal and Tenorio Volcano, where its known 

 range terminates abruptly." 



THAMNOPHILUS NIGRICEPS NIGRICEPS Sclater: Black 

 Ant-shrike, Pavita Hormiguera Negra Menor 



Thamnophilus nigriceps P. L. Sclater, Proc. Zool. Soc. London 1868, pt. 4 (April 

 1869, p. 571. ("Bogota" = northern Colombia.) 



A typical ant-shrike but male entirely black, female and immature 

 male with back chestnut ; head and under surface heavily streaked 

 with white to bufify white. 



Description. — Length 140-155 mm. Adult male, plumage deep 

 black, with the flank feathers, mainly concealed, very dark slate, the 

 under wing coverts and hidden inner webs of the wing feathers white 

 and the under wing coverts spotted and barred lightly with black. 



Adult female, back, wings, and tail cinnamon-brown ; crown, hind- 



