90 RUDOLF .SÖDERBERG, STUDIES OF THE BIRDS IN NORTH WEST AUSTRALIA. 
On the l7th of April and the 4th of Aug. I shot some more juvenals, which 
were even then in moulting and had partly obtained the male plumage. The former 
of these birds was probably born in the ordinary breeding season and consequently 
had its first moulting: shortly after the end of the summer and was about to get 
some few feathers of the plumage of the adult male (corresponding to the autumn 
moulting in our country?). These feathers are partly black, partly grey, all the other 
feathers of the plumage having the juvenal character. 
A juvenal '/s is also moulting, having pins in the neck and back with black 
feathers mixed in, indicating the beginning of the male plumage. The moulting is 
only in embryo. 
From this examination we can see that juvenals in moulting are found during 
the greater part of the year, and that in a juvenal the moulting that has begun in 
April might stop, but that the bird at any rate wears the mixed plumage until Aug. 
or Oct. in order to continue the moulting at this time: It seems as if this moulting 
could keep on still longer than in the adults even if, as is the case in other species, 
different parts of the feathering are not changed at different times. (This is gene- 
rally the case in the wings and tail.) A young male shows in Dec. a complete black 
dress in which the small feathers have been changed to real male plumage, but where 
wing- and tail-feathers have not been yet dropped. These plumes seem, however, 
never to have been dropped (not in April) but belong to the dress of the nestling 
and are apparently only now on the point of being dropped and replaced. Thus we see 
that moulting of some part of the plumage in a specimen may be, as it were, skipped 
over and only take place later on, when the next moulting-season comes. (The parts 
that are to have the sexual characters are in certain species subjected to earlier 
moulting.) 
Moulting-season. — A migratory bird that begins its moulting shortly after 
its arrival at the country. What is the case with the moult in the adult birds in 
April, I have not had any opportunity to observe. Adult birds have been found 
moulting in Oct., Dec. and Jan. 
Description. 
Juvenal &... 1): The first year. 
Like the female. Earthy brown, very broad sandy-buff margins to the wing- 
coverts: and secondaries, which are black or brown-black, so also the PRIMasigR and 
tail- re 
2) After the first moulting. (Plate 1, fig. 4a.) Black. feathers developed among 
the brown ones on the back. The wing-coverts white, with black centres and sandy- 
buff margins. Secondaries black with white margins, primaries black; so also the 
rectrices. In Mowla Downs a singing young male was shot, with a plumage, similar 
to that of the juvenal after the first moulting. It was probably breeding (cf. Ptero- 
podocys maxima pallida). 
