88 
GENERAL OBNITHOLOGY. 
highly important special '^flight-feathers" of the wings and rudder-feathers" of the tail are 
to be examined beyond, in describing those members for purposes of classification. 
Endysis and Ecdysis. — Putting on and oflF Plumage. — Newly hatched birds are 
covered for some time with a kind of dow^n, entirely different from such feathers as they ulti- 
mately acquire. It is scanty, leaving much or all of the body naked, in most altricial birds^ 
such as are reared by the parents in the nest (Lat. altrix, female nourisher) ; but thick and 
puffy in some Altrices, and in all Prcecoces (Lat. prcBCOX, precocious), which run about at birth. 
Since many birds which require to be reared in the nest are also hatched clothed, or very speedily 
become downy, a more exact distinction may be drawn by using the terms ptilopcedic and psilo- 
pcBdic (Gr. tttlXov, ptilon^ a feather ; \/^tXos, psilos, bare ; and nais, pais, a child) respectively 
for those birds which are hatched feathered or naked ; a chicken and a canary-bird are familiar 
examples. It is the rule, that the higher birds are born helpless and naked, requiring to be 
reared in the nest till their feathers grow ; the reverse with lower birds, as the walking, wading, 
and swimming kinds ; and a primary division of birds has even been proposed upon this physio- 
logical distinction. It offers, however, too many exceptions ; thus, no birds are more naked 
and helpless at birth than young cormorants. Probably all prjecocial birds are also ptilopaedic 
and all psilopsedic birds altricial 5 but the converse is far from holding good, many altrices, as 
hawks and owls, being also ptilopaedic. In other words, psilopaedic birds are always altricial, 
but ptilopaedic birds may be either altricial or praecocial. In any case, true feathers are soon 
gained, in some days or weekg, those of the wings and tail being usually the first to sprout. 
The acquisition of plumage is called endijsis (cvbva-it, endusis, putting on). The renewal of 
plumage is a process familiar to all, in its generalities, under the term ''moult," or ecdysis 
(Gr. e/cSuo-iy, ekdusis, putting off). Feathers are of such rapid growth, and make such a drain 
upon the vital energies, that we easily understand how critical are periods of the change. 
The first plumage is usually worn but a short time ; then another more or less complete 
change commonly occurs. The moult is as a rule annual ; and in many cases more than 
one moult is required before the bird attains the perfection of maturity in its feathering. 
It is well known how different many birds are the first year in their coloration from that 
afterward acquired ; sometimes changes progress for several years ; and some birds appear 
to have a period of senile decline. All such changes are necessarily connected, if not 
with actual moult, as is the rule, then at any rate with wear and tear and repair of the 
plumage. The first plumage being gained, under whatever conditions peculiar to the species, 
it is the general rule, that birds are subject to single, or annual, moult. This commonly occurs- 
in the fall, when the duties of incubation are concluded, and the well-worn plumage most needs 
renewal. This once-a-year moult, at least, happens to nearly or quite all birds. Many, 
however, moult twice a year, the additional moult usually occurring in the spring-time, when 
a fresh nuptial suit is acquired ; in such cases, the moult is said to be double, or semi-annual. 
Such additional moult is generally incomplete ; that is, all the feathers are not shed and 
renewed, but more or fewer new ones are gained, with more or less loss of the old ones, if 
any. The most striking ornaments donned for the breeding season, as the elegant plumes 
of many herons, are usually worn but a brief time, being doffed in advance of the general 
fall moult. A few birds, as the ptarmigan (Lagopus), regularly have even a third or triple 
moult, shedding many of their feathers as usual in the early autumn, then changing 
entirely to pure white for the winter, then in spring moulting completely to assume their 
wedding-dress. As a rule, feathers are moulted so gradually, particularly those of the wings 
and tail, and so simultaneously upon right and left sides of the body, that birds are at no time 
deprived of the power of flight. The first flight-feathers acquired by young birds are usually 
kept till the next season ; but in those that fly very early, before they are half grown, as so 
many gallinaceous birds do, their first weak wing-feathers are included in the general moult 
