RED-BACKED SHRIKE. 159 



female of the Red-backed Slirike also resembles the male, 

 but does not acquire that state of plumage in any single 

 year, nor until after having moulted several times ? Though 

 not believed formerly, it is now very well known that many 

 birds build nests and produce young before they have attain- 

 ed their own adult plumage. 



Baron Cuvier has stated, that when the adult female bird 

 differs from the male in the colour of her plumage, the young 

 birds of both sexes, in their first feathers, resemble the female ; 

 the young males afterwards putting forth the colours that 

 indicate their sex. When the adult male and female are of 

 the same colour, the young then have for a time a plumage 

 peculiar to themselves. The Pheasant may be quoted in 

 illustration of the first law, and the Partridge as an ex- 

 ample of the second. To these two, a third law may be 

 added : whenever adult birds assume a plumage during the 

 breeding season decidedly different in colour from that which 

 they bear in the winter, the young birds have a plumage in- 

 termediate in the general tone of its colour compared with 

 the two periodical states of the parent birds, and bearing also 

 indications of the colours to be afterwards attained at either 

 period. 



There are various modes by which changes in the appear- 

 ance of the plumage of birds are produced. 



By the feather itself becoming altered in colour. 



By the bird's obtaining a certain addition of new feathers 

 without shedding any of the old ones. 



By an entire or partial moulting, at which old feathers are 

 thrown off and new ones produced in their places. And by 

 the wearing off the lengthened lighter coloured t[Y>H of the 

 barbs of the feathers on the body, by which the brighter 

 tints of the plumage underneath are exposed. These changes 

 will be noticed under the different species most affected by 

 them. 



