394 External Changes in Birds, 



in hand. For my own part, I have little time for practical 

 observation ; but, having long been in the habit of keeping a 

 number of birds (chiefly the smaller kinds which occur in 

 Britain) in a state of captivity, I have thus enjoyed some 

 very favourable opportunities for making myself fully ac- 

 quainted with the various changes that a great number of 

 species undergo, both seasonally, and in their progress from 

 youth to maturity and old age ; and I have neglected no 

 opportunity of studying those of other races, which circum- 

 stances may have variously chanced to place in my way. 



It is to be remarked, then, that some species of birds (as, 

 for example, the larks and starlings, the crows, the wood- 

 peckers, and various others) moult the whole of their im- 

 mature, or nestling, plumage the first year, including the wing 

 and tail primaries ; while a very few (as the bearded pinnock, 

 Calamophilus biarmicus, and rose mufflin*, Mecistura rosea) 

 shed the primary feathers of the tail the first season, but not 

 those of the wing: numerous other races (as all the modi- 

 fications of the fringillidous and thrush types) moult their 

 clothing plumage very soon after leaving the nest, and retain 

 the primaries till the second autumn ; the Falconidae, again, 

 and some others, undergo no change whatever until that 

 period. All those which I have as yet mentioned change 

 their feathers only once in the year, towards the close of 

 summer, immediately on the cessation of the duties towards 

 their progeny : but there are various other tribes (as the wag- 

 tails and pipits, Motacillinae, and most of the aquatic races) 

 which regularly undergo another general moulting in the 

 spring; though in no instance, that I am aware of, are the 

 primary wing feathers shed more than once in the year : those 

 of the tail, however, in some rare instances, are; and the dif- 

 ferent coverts, together with the secondary and tertiary wing 

 feathers, in most, if not all, double-moulting birds, are 

 changed twice. In some migrative species (as the cuckoo, and 

 most of the swallows), the young of the year do not change 

 their plumage until the winter months; whereas the old 

 birds moult in autumn; and in other birds, again (as in 

 various ducks [VIII. 544, 545.] ), two general changes of 

 feather take place within the short period of about four 

 months. Very many other similar diversities, of a more or less 

 subordinate character, might be enumerated, if enough have 

 not been already mentioned to show that a wide field for ob- 

 servation is here open to the practical ornithologist. 



In like manner may analogous diversities be observed 



* Parus caudatus Linncens. 



