BIRDS OF ETHIOPIA AND KENYA COLONY 89 



IMouritz * records it as orange yellow, while still others write that 

 the iris is red or red brown. 



In a series of six examples of the black phase the color of the 

 tarsus varies from yellowish orange to black. Intermediates have 

 some of the scutes black and others yellowish, but none have the 

 scales actually intermediate in color. 



This hawk has been considered to have two races, the southern one 

 being the typical form, the northern {niger) said to be larger and 

 paler. Swann ^ has given the ranges of these two and also the size 

 limits of each form. Sclater ^ does not recognize niger. I have 

 examined a series of 30 specimens from Ethiopia, southwest Arabia, 

 Sudan, Kenya Colony, Tanganyika Territory, and South Africa, and 

 am unable to support Swann's contention as to the validity of the 

 two races. According to this writer the southern birds have wings 

 measuring from 176-190 in the male, and from 190-204 millimeters 

 in the female. The northern birds are said to have the following 

 wing measurements; male, 190-195 (one 203) ; female, 205-212 milli- 

 meters. However, I find that an adult female from South Africfj has 

 a wing 209 millimeters in length while a comparable specimen from 

 the White Nile (identified by Swann as niger) has a wing of only 

 200 millimeters. Birds from the same locality vary considerably in 

 size, and, on the whole, it seems that slight size differences mean very 

 little in this species. It is rather curious, however, to find that 

 melanistic specimens are usually somewhat (occasionally consider- 

 ably) smaller than normal birds of the same sex from the same 

 locality. Thus, a black male from Morogoro, Tanganyika Territory, 

 has a wing 182 millimeters long; tail, 155; culmen from cere 13.0 

 millimeters, while a normal male from the same place has the follow- 

 ing measurements : Wing, 190; tail, 169 ; culmen, 13.5 millimeters. A 

 black female from South Africa measures as follows: Wing, 198; 

 tail, 165; culmen, 14.5 millimeters; while a normal one from the 

 same country has a wing 209 millimeters long; tail, 164; culmen, 14.5 

 millimeters. 



Aside from size differences, the northern form niger is said to be 

 paler than typical gahar. This I am likewise unable to uphold. 

 There certainly is considerable variation in the color of the back and 

 upper parts generally, and of the breast as well, but such differences 

 in shade as occur are not geographical, but merely individual, and 

 possibly due to age. 



Immature birds show greater color variations than do adults. As 

 a rule, the upper tail coverts are more nearly pure white in young 

 males than in young females. Every immature bird of the latter 



*Ibis, 1915, p. 200. 



"Idem, 1923, p. 610. 



• Syst. Avium Ethiop., 1924, p. 72. 



