424 BULLETIN" 15 3, UNITED STATES NATIONAL MUSEUM 



In Ethiopia the molt (of the remiges and rectrices at any rate) 

 comes in March and April, as it does in Kenya Colony. As in 

 many hornbills, the tail molt is rather irregular. Thus, one speci- 

 men has replaced the middle rectrices only and has them about one- 

 third grown, another has replaced the middle pair, the next pair 

 are old, the next pair new, and the two outer pairs old, while a third 

 individual has the innermost and the outermost rectrices new, the- 

 rest old. In the remigial molt, there seem to be two centers from 

 which the ecdysis spreads, the innermost and the next to the outer- 

 most primaries. However, here, too, there is considerable variation. 

 A male collected on May 4 at Gato River has replaced primaries 4, 

 7, and 10, and has not shed the others, which are of the old plumage. 

 It is noteworthy that of the series collected at Gato River (18 birds) 

 between April 1 and May 4, all the specimens that are in molt were 

 mated birds according to the collector's notes. Erlanger " found 

 the breeding season in Ethiopia to be in February and March. It 

 appears therefore that the birds remain in pairs until the end of the 

 postnuptial molt. This is rather significant when we consider their 

 nesting habits. The female and young are practically imprisoned 

 in a hole in a tree until the latter are fully grown, and when they 

 first come out of the nest their flight is very weak and uncertain and 

 the light is rather dazzling to their eyes. This I know from per- 

 sonal field experience with Loyhoceros Tivelanoleucos. The male be- 

 gins to go through the postnuptial molt while his mate and young 

 are still in the nest, and, inasmuch as he has to be flying to and from 

 the nest with food almost constantly, the molt is necessarily a rather 

 slow, irregular process. The female and the nestlings, however, 

 molt all the wing and tail quills almost at once and the new ones are 

 not fully grown when they leave the nest. In fact, the long rectrices 

 would probably be broken in the crowded confines of the nest if 

 they were to develop to their full length there. The duration of post 

 nesting family association seems to be directly correlated with the 

 completion of the postnuptial molt of the adults (which is synchro- 

 nous with the development of the juvenal feathering of the young). 

 Adults vary considerably in the size and presence of white spots 

 on the outer webs of the outer primaries, but this character appears 

 to be wholly individual, and in no way correlated with sex or age. 

 As a rule the two outermost primaries have no white spots ; the third 

 has such a spot in about half the birds examined, the fourth and 

 fifth in practically all. There is never more than a single spot on 

 each feather, and the white area varies in length from 9 to 25 

 millimeters. 



" Journ. f. Ornith., 1905, pp. 441-442. 



