94 BULLETIN 15 3, UNITED STATES NATIONAL MUSEUM 



and less uniform than in the ju venal plumage ; the chin and throat 

 are pale buffy streaked with blackish brown; the breast and abdo- 

 men are darker brown, the former streaked with terminally lanceo- 

 late shaft streaks of blackish brown, the latter pale rufous brown 

 barred with darker rufous brown and tipped with sandy tawny; 

 the flanks very light, pale tawny broadly barred with dull chocolate 

 brown ; thighs light tawny narrowly barred with brown ; under tail 

 coverts like the thighs but broadly barred with pale rufous brown; 

 under wing coverts largely whitish or buffy white marked with 

 brown. 



However, all birds, apparently of tliis age, are not like this one. 

 Thus, a young bird from Gaboon (Mus. Comp. Zool. 33128) is much 

 lighter below, except that the streaks on the throat and breast are 

 blacker, and, instead of being merely shaft streaks, comprise the 

 entire distal halves of the feathers. The upper parts are much 

 blacker also, particularly the hind crown, occiput, nape, and inter- 

 scapulars. The tail is of the juvenal type. 



The next plumage is characterized by lighter underparts and by 

 very broadly barred rectrices (bars about 1.5 inches or more in 

 width). The lighter bars on the tail feathers are brownish gray, not 

 gray as in the adults. These birds vary enormously : Some are 

 heavily barred on the abdomen, others very slightly so; some have 

 the thighs barred, others unbarred. The oldest immature bird (male, 

 Avakubi, Belgian Congo, J. P. Chapin coll. A.M.N.H. 157760) has 

 the entire chin, throat, and breast pure pale tawny buff with no dark 

 markings at all. The thighs are almost unbarred as well. 



Apparently the appearance of narrow bars on the flanks and 

 thighs is not necessarily a sign of approaching maturity, as one bird 

 in the first postjuvenal plumage has such markings while older 

 birds do not. 



The systematics of this hawk have been studied most recently by 

 Swann, who recognizes four races.^- Inasmuch as I have not suffi- 

 cient material to judge of all of them, the following notes are neces- 

 sarily brief. 



According to Swann the four races are as follows : 



1. G. t. typicus. — South, east, and northeast Africa. 



2. G. t. pectoralls. — Tropical West Africa. Cameroon to Nigeria 

 ( ?) ; said to be smaller than typicus, wing (female) 405 millimeter, 

 more heavily barred with black, the black bars nearly equal to the 

 white ones. 



3. G. t. kempt. — Sierra Leone; much smaller than typicus, wing 

 (male) 360, (female) 392 millimeters; paler generally than typicus, 

 the white edges on the wings and the white ventral bars broader. 



i^Monog. Birds of Prey, pt. 2, pp. 97-101. 



