88 GENERAL OBNITHOLOGT. 



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 off Plumage. — Newly hatched birds are 

 covered for some time with a kind of down, entirely difterent from such feathers as they ulti- 

 mately acquire. It is scanty, leaving much or all of the body naked, in most altridal birds, 

 such as are reared by the parents in the nest (Lat. altrix, female nourisher) ; but thick and 

 puffy in some Alirices, and in all Prcecoces (Lat. prmcox, 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 pUhpcedic and psilo- 

 pcedic (Gr. jttiKov, ptilon, a feather; i/^iXor, psilos, bare; and ttcus, 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 bom 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 oflFers, however, too many exceptions ; thus, no birds are more naked 

 and helpless at birth than young cormorants. Probably all prsecocial birds are also ptilopsedic 

 and all psilopsedic birds altricial ; but the converse is far from holding good, many altrices, as 

 hawks and owls, being also ptilopsedic. In other words, psilopsedic birds are always altricial, 

 but ptilopsedio birds may be either altricial or prsecocial. In any case, true feathers are soon 

 gained, in some days or weeks, those of the wings and tail being usually the first to sprout. 

 The acquisition of plumage is called endysis (evSva-tt, endusis, putting on). The renewal of 

 plumage is a process familiar to all, in its generalities, under the term "moult,'' oi ecdysis 

 (Gr. eicSvcTK, 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 witli 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 aU 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 ptire 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 tiU 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 



