596 MOULT 
here we have briefly to consider the different phases which the act 
of Moulting offers. 
As a general rule all kinds of Birds are subject to an annual 
Moult, and this commonly begins immediately on the close of the 
breeding-season, but, as will be presently explained, there are 
some which undergo in addition a second or even a third partial 
change of plumage, and it is possible that there may be others still 
more exceptional: our information respecting these, however, is too 
meagre to make it worth while saying anything here about them. 
It must be acknowledged that with regard to the greatest number 
of forms we can only judge by analogy, and though it may well be 
that some interesting deviations from the general rule exist of 
which we are altogether ignorant, yet when we consider that the 
Ratitx, so far as observed, moult exactly in the same manner as 
most other birds,! the uniformity of the annual change may be 
almost taken for granted. 
It is not intended here to say more (cf. p. 248) of the way in 
which a feather dies and a new one succeeds it, nor need we com- 
pare the process of moulting with the analogous shedding of the 
hair in Mammals or of the skin in Reptiles, though the latter, in 
the case of the flipper-like wings of the PeNcuIN—the scaly feathers 
of which come off in flakes—Mr. Bartlett (Proc. Zool. Soc. 1879, p. 
6) has shewn to be remarkably close. Enough for our present 
purpose to see that such renovation is required in Birds, nearly all 
of which have to depend upon their quills for the means of loco. 
motion and hence of livelihood. It is easy to understand that dur- 
able as are the flight-feathers, they do not last for ever, and are 
beside very subject to accidental breakage, the consequence of 
which would be the crippling of the bird.? It is obviously to pro- 
vide against what in most cases would be such a disaster as this last 
that we find the remiges, or quill-feathers of the wings, to be nearly 
always shed in pairs. ‘They drop out not indeed absolutely at the 
same moment, though this sometimes seems to happen, but within 
afew days of each other, and, equilibrium being thus preserved, 
the power of flight is but slightly deteriorated by their temporary 
loss. The same may be observed in a less degree, since there is 
less need of regularity, with the rest of the plumage, as a little 
attention to any tame bird will shew, and the new feathers grow at 
an almost equal rate. In the young of most species the original 
quills are not shed during the first year, nor in the young of many 
does there seem to be an entire moult during that time, but in the 
1 For the knowledge of this fact I am indebted to the vast experience of Mr. 
Bartlett. 
2 By an ingenious but simple process known as “‘imping,” which properly 
means engrafting, and is described in almost every book on hawking, falconers 
repair any broken flight-feather, and so restore the bird to its full power. 
