SILVERBILL 159 
sumably females or young) were met with almost 
every day for nine weeks, and frequently in large 
numbers. Of course I began to suspect that the 
males must moult into a brown suit after nesting, as 
do our Bobolinks and many other birds, but I shot 
specimens at various times, and all proved to be 
either females or young males, and as I was confident 
that at Concepcion black males were to be found 
through the year, I was at a loss for an explanation, 
and am so still.” 
The male Silverbill is entirely black, there 1s 
nothing in nature blacker than its plumage; and, to 
enhance the effect, the beak is of a very delicate 
primrose-yellow, which at a little distance appears 
white, hence the vernacular name. The eye, and 
broad free skin surrounding it, which is ruffed like 
an Elizabethan collar, are of the same faint primrose 
hue. The secondary wing-quills are pure white, but 
the white is only displayed when the bird flies. The 
female has the naked skin encircling the eye, but its 
colour, as also that of the beak, is much darker than 
in the male. Entire upper plumage dark brown ; 
secondaries chestnut; lower parts fawn-colour, 
marked with brown. The young males are at first 
like the females in colour, and do not acquire the 
black plumage until the end of the summer. 
The bird ranges over the whole of the Argentine 
Republic, and, according to Gay, is also common 
throughout Chili, where it is known as the Colegial 
(Collegian or learned person), on account of its stiff 
grave manner, black dress, and spectacled appearance. 
