FAMILY TYRANNIDAE 485 



more actively, though briefly, with little flocks of other small forest 

 birds. Their low calls, with slight carrying power, are rendered 

 by Eisenmann as a sibilant pseoo-see. In the nesting season in March 

 and April, when pairs may be seen, they make a curious, low rattling 

 sound by fluttering the wings slightly as they rest quietly on a perch. 

 On one occasion I saw two in an attractive display in which both 

 wings were suddenly extended and thrust upward vertically for a 

 second and then folded quickly. 



Information on their breeding is detailed in an account by Skutch 

 (Pac. Coast Avif., no. 34, 1960, pp. 534-538), mainly from observa- 

 tions on Barro Colorado Island between March and May. He writes 

 that "the pensile nest is attached to the end of a slender, drooping 

 twig, to a thin, dangling vine, or beneath a palm frond." The female 

 worked alone fastening fibrous materials to the end of the hanging 

 support, and then pushed into this mass to make a rounded space 

 in which the nest was formed with additional fibers and bits of leaves. 

 One nest on Barro Colorado had a rounded base tapering upward for 

 a length of 230 mm to its point of suspension. "A roughly spherical 

 chamber occupied the lower third of the structure. This was entered 

 through a round doorway in the side, above which was a visorlike 

 projection" that afforded shelter from rain. Another nest was frailer 

 in construction. Two sets, each of two eggs, were seen, these being 

 white with scattered irregular blotches of chocolate that joined to 

 form a heavy wreath around the large end. Three of the eggs 

 measured 15.9x11.9, 15.5x11.9, and 15.9x11.1 mm. Incubation 

 and subsequent care of the young were duties of the female alone, 

 with no male in attendance. Young at hatching had pink skin and 

 were without down. 



From his observations Skutch concluded that this flycatcher "does 

 not form pairs, and the female receives no aid in attending the nest." 



While Terenotriccus currently is placed near the genus Empidonax, 

 some of its actions, especially the elevation of the wings, are sug- 

 gestive of Pipromorpha. In preparing specimens, I have noted that 

 the pattern of the dorsal pterylosis is peculiar, as is that of the tarsus 

 with its slight indication of scutellation. 



PRAEDO AUDAX Nelson: Black-billed Flycatcher, 

 Moscareta Piquiprieta 



Praedo audax Nelson, Smithsonian Misc. Coll., vol. 60, no. 3, September 24 

 (Sept. 27), 1912, p. 15. (Cana, 550 meters elevation, Cerro Pirre, Darien.) 



Small ; greenish olive above ; yellowish on lower surface ; two bufif 

 wing bars ; a white line from lores to above eye. 



