BIRDS 3OI 



We have thirteen male specimens taken during the second half of 

 February at Elizabeth Bay. The males are mostly in the black 

 plumage and have black bills. Two are intermediate between stages 

 V and VI. One is in Stage V but has the bill entirely black. The 

 nesting season here had apparently just begun at this time. It is 

 probable that it is of short duration as it is at Tagus Cove, and the 

 birds have time to acquire the black plumage before they begin to 

 breed. 



There is a slight seasonal change in the plumage of the females due 

 to the age and consequent abrasion of the feathers. Specimens taken 

 in March compared with specimens taken in January average darker 

 below with less of the pale color of the marginal parts of the feathers. 



Only three of our specimens of females taken in March have per- 

 fectly black bills. In some cases the gonys is almost entirely yellowish 

 and this is true of birds taken mated with males. Only two of the 

 January specimens have dusky bills. Hence the bills of the females 

 do not as a rule become black by the end of the first year, and ap- 

 parently seldom become perfectly black, showing a tendency to remain, 

 as does the plumage, in a non-melanistic condition. In this respect 

 they differ from the males, which apparently regularly acquire black 

 bills by the beginning of the breeding season. 



Nature of the Change from one Phase of Plumage to the Next 

 Moulting. The change in color of the males from the young to the 

 adult consists not only of a spreading of the dark color from the head 

 over the posterior parts, but also of a change from brown to black. 



Of eleven breeding males taken at Tagus Cove in March three are 

 in a plumage that could have been produced from the plumage of 

 January birds in Stage V by abrasion of the pale tips of the feathers. 

 The pale color is very conspicuous below on the belly, flanks and 

 crissum, but less so than in typical examples of Stage V. The black 

 of the other parts, especially of the back and rump is not intense as in 

 birds most typical of Stage VI, but has a very distinct brownish tone. 

 The tail and wing feathers are also much paler and more decidedly 

 brownish than in the most melanistic forms. These brownish-black 

 forms could not pass over into the purely black phase without a moult 

 involving a change of color in the feathers, although they might be 

 produced from Stage V simply through abrasion of the feathers. 



We have one specimen, taken at Tagus Cove in February, which 

 is in a stage intermediate between Stages V and IV. This specimen 

 is moulting, but the new feathers coming in have the same pale edges 

 and brown subterminal areas as the old ones. 



