AFRICAN YELLOW-BILLED DUCK 
117 
other observers describe them as more tame than other ducks, such as Anas sparsa or 
Casarca ferruginea (Ogilvie-Grant, 1900; Buckley, 1874). In Abyssinia the Gallas 
are said sometimes to kill them with sticks shaped like Australian boomerangs 
(Ogilvie-Grant, 1900). 
Gait, Swimming, Diving, Flight. On land and in the water its appearance is 
absolutely MaUardlike, although it has a way of exposing the very beautiful specu- 
lum rather more than most true ducks do. Its style of flight, so far as I know, is in- 
distinguishable from that of the Mallard, but when on the wing it is said to appear 
bluish in color (Ayres, in Layard, 1875-84). It is apparently not usually found in 
large flocks, but like the other Mallardlike ducks it stays in pairs or in small com- 
panies of from six to twenty (W. L. Sclater, 1912a; et al.). 
Voice. The notes of the Yellow-bill are indistinguishable from those of the 
Mallard (Rogeron, 1903; Horsbrugh, 1912). I can And no description of the tra- 
cheal bulb. 
Food. No good observations as to the stomach-contents are to be found in the 
literature, but a few writers have remarked their feeding on a vegetable diet. When 
the grain is ripe they flight to the grain-fields in the evening, returning to the water 
to wash and rest (Horsbrugh, 1912). 
CouETSHiP AND NESTING. The breeding season in South Africa falls mostly in 
October (Layard, 1875-84). Nevertheless nests have been found in April (Sparrow, 
1907). Over the rest of its range the season is exceedingly irregular. In the Transvaal 
the birds were just commencing to moult in March and April, and five quite young 
birds were found on April 4 (W. L. Sclater, 1912a). In East Griqualand broods have 
been found in April (Horsbrugh, 1912). In the Mt. Kenia region (British East 
Africa) a female with young in down was found at a high altitude on March 27 
(Lonnberg, 1912). For East Africa in general it certainly breeds from Eebruary to 
May (V. van Someren, 1922), and probably at other times. In southern Abyssinia 
von Erlanger (1905) found it breeding in June, while in the Lake Tana region, 
according to von Heuglin (1873) it breeds in November and December, and full- 
grown young were found in March and April. 
Heinroth (1911), the only observer who mentions the display, says that it closely 
resembles that of the Mallard. Pursuit flights just like those seen in so many northern 
ducks have been noticed during the breeding season. The drakes, says C. G. Davies 
(1911), pursue the ducks in the air, sometimes circling round to a great height, “the 
female turning and dodging in every direction, and quacking loudly.” 
Very little is recorded as to the location of the nest. The birds usually select the 
