FAMILY SYLVIIDAE 



185 



Bejuco in the west to Cerro Chucanti in the Serrania de Maje in the 

 east; in Colon at Punta Pilon on the Rio Indio; San Bias at Mandinga, 

 and Darien at Pucro and Jaque. 



Ramphocacnus dwells in viny tangles of undergrowth and in lower 

 trees where it moves wrenlike, cocking its tail, and flicking it constantly 

 from side to side, rarely coming to the ground or foraging more than 

 10 m above it. The diet, as evidenced by the stomach contents of a fe- 

 male collected by Hallinan (Auk, 1924, p. 319) at Farfan, Canal Zone, 

 is small insects and small seeds. Two collected by Burton (Bull. Brit. 

 Orn. Club, 1975, p. 85) weighed 9.0 and 11.0 g. 



This bird is usually found singly or in pairs. Its song is a distinctive 

 musical trill on a single pitch, sometimes rising and then lowering in 

 volume at the end. A sharp wrenlike ticking and a low, dry churr are 

 some of its other calls. 



In Panama the nesting season runs from at least late April to July. 

 Willis, on Barro Colorado Island in 1961, saw a bird on its nest on 

 April 23 and another building a nest on July 6 (Willis and Eisenmann, 

 Smiths. Cont. Zool., 1979, p. 25). Ridgely (in litt.) observed a pair 

 feeding a very recently fledged young bird in the wind-swept elfin cloud 

 forest on Cerro Jefe (1000 m), eastern Province of Panama, on July 

 24, 1975. Bond and de Schauensee (Acad. Nat. Sci. Philadelphia, 

 Mon. no. 6, 1944, p. 40) mention a female collected at Garachine that 

 had enlarged ovaries on May 8, 1941. A male I took at Sona, Veraguas, 

 on May 25, 1953, was in full breeding condition. The only published 

 description from Panama of the nest is of one found by Eisenmann 

 (Auk, 1953, p. 369) in the Juan Franco suburb of the city of Panama 

 on July 15, 1950, when it contained 2 almost naked young. The nest, 

 an open cup, was in a damp thicket, near a stream, about 15 cm off the 

 ground, in a small shrub shaded by trees. It was built among the shrub's 

 vertical shoots and was composed "chiefly of grass-stems, with a few 

 twigs and dried leaves and to the exterior were attached several large 

 dried leaves that hung loosely along the sides and extended below the 

 nest proper, forming a sort of ornamental skirt." The measurements 

 were exterior diameter approximately 10 cm; interior diameter 8 cm; 

 exterior depth 12.5 cm; interior depth 8 cm. 



Skutch (1960, Pac. Coast Avif., no. 34, pp. 54-61) found a nest of 

 Ramphocaenus in Costa Rica on April 6, 1939, the first egg being laid 

 on April 14 and the second the following day. These were "white, 

 lightly sprinkled with fine, pale cinnamon spots over the whole surface, 

 with these markings heaviest at the thick end." Measurements were 

 19.8 X 14.3 and 19.1 X 13.5 mm. The incubation period at this nest was 



