THE ASSUMPTION AND CHANGES OF PLUMAGE IN BIRDS. 15 
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 a plumage 
peculiar to themselves. To these laws which appear to govern the assumption of plu- 
mage in young birds, and of the first of which (to select in illustration examples the most 
familiar among land and water birds,) the various Pheasants and Ducks may be named ; 
and of the second, the Partridges and Gulls; 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 intermediate 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 three modes by which changes in the appearance of the plumage of birds 
are produced :— 
By the feather itself becoming altered in colour. 
By the bird’s obtaining a certain number of new feathers without shedding any of the 
old ones ; and 
By an entire or partial moulting, at which old feathers are thrown off, and new ones 
produced in their places. 
The first two of these changes are observed in adult birds at the end of spring, indi- 
cating the approach of the breeding season ; the third change is partial in spring, and 
entire in autumn. That the colours of the plumage are more brilliant during the 
breeding season is well known; and ichthyologists have observed that the scales of 
fishes become brighter as the season for spawning approaches. 
A fourth mode may be noticed, though its effects are limited. It is observable in 
spring, as the breeding season approaches, by the wearing off of the lengthened lighter- 
coloured tips of the barbs of the feathers on the body, by which the brighter tints of the 
plumage underneath are exposed, as has been noticed by Sir William Jardine and 
Mr. Blyth. The effect is most conspicuous in the Buntings, Finches, and Warblers. 
Young birds of the year in various species, after the autumn moult, continue through 
the winter to assume, by degrees, the more intense colours characteristic of adults, 
without changing the feather. This colour commences generally at that part of the 
web nearest the body of the bird, and gradually extends outwards till it pervades the 
whole feather. 
In many birds the spring change is common to both sexes, as in the species of the 
genera Limosa, Tringa, Totanus, Phalaropus, &c. In others the males only are af- 
fected. The rapidity of this assumption of vivid and particular colours previously to the 
breeding season bears a relation to the sexual vigour of the birds; and one of the 
great objects of existence being accomplished in the reproduction of the species, the 
plumage almost immediately indicates the commencement of a return to the colours 
peculiar to winter. 
