236 BIRDS OF THE REPUBLIC OF PANAMA PART 2 



Small, with distinctly grayish white rump. 



Description. — Length 110-115 mm. Adult (sexes alike), upper sur- 

 face, including wings, tail, and upper tail coverts glossy, faintly bluish, 

 black ; rump pale grayish white, shading to pale gray on lower back, 

 the shafts of the feathers black ; throat and f oreneck grayish white ; 

 side of head, neck, and chest deep mouse gray, changing to blackish 

 slate on breast, sides, and abdomen; under tail coverts and under 

 surface of wings slate-black. 



Immature, somewhat duller, less glossy above ; slightly more 

 fuscous-black below. 



This species is widely distributed in Panama, throughout the Pa- 

 cific slope, and from the Canal Zone eastward on the Caribbean side. 

 When it passes low and near at hand the pale rump is often visible, 

 a mark that distinguishes it from other species of the genus. It is thus 

 the only one for which sight records may be accepted as fairly certain. 



Two geographic races distinguished by slight differences in size 

 are found in Panama. 



CHAETURA SPINICAUDA FUMOSA Salvin 



Chaetura fumosa Salvin, Proc. Zool. Soc. London, Nov., 1870, p. 204. (Bugaba, 

 Chiriqui.) 



Characters. — Larger, wing 107.5-115.4 mm. 



Measurements. — Males (13 specimens from Costa Rica and Chi- 

 riqui), wing 107.7-115.4 (109.8), tail 37.7-42.2 (39.4), oilmen from 

 base 4.8-5.5 (5.1), tarsus 9.8-1 1.8 (10.6) mm. 



Females (9 from Costa Rica), wing 107.5-113.4 (109.8), tail 36.8- 

 41.5 (39.8), culmen from base 4.6-6.0 (5.3), tarsus 9.6-11.6 (10.5) 

 mm. 



Rare. Status uncertain ; known in Panama only from Bugaba, the 

 type locality, and Puerto Armuelles in western Chiriqui. 



In March 1966, in the area known as Oliva near the coast north of 

 Puerto Armuelles, Chiriqui, occasionally in early morning a flock of a 

 dozen small swifts circled briefly over the trees. On March 3 they 

 came within range so that I was able to secure a male that identified 

 them as of this race. The only others that I have examined from 

 Panama are 4 in the British Museum (Natural History) collected by 

 Enrique Arce, and marked 1870. Salvin, in his original description, 

 gives a diagnosis of characters in Latin, with the following measure- 

 ments and locality "long, tota 4.5, alae 4.1, caudae 1.75. Hab. Bugaba 

 (Arce)." Two of the 4 skins are labeled Bugaba. The other 2 bear 

 only the locality "Veragua." When I examined these birds I found 



