4 6



Dr. A. G. Butler,



As with Butterflies, so is it with Birds; difference of

plumage, even when it is not sexual, is by no means always

indicative of specific distinctness : in some cases it merely stands

for youth, as in the case of Calcenas gouldice of Gray with its

greenish-black tail, which proved to be merely the young form

of the common Nicobar pigeon : of course this is by no means

an isolated instance. Then again there may be difference of

structural outline without appreciable difference of plumage due

to the same cause, as I have pointed out in the case of the

Bluebird I bred, which, after it had attained its adult male

colouring, still possessed the broad bill characteristic of a

young bird.


The seasonal plumages of Birds have doubtless been re¬

sponsible for considerable additions to ornithological synonymy :

it is impossible for this to have been avoided, until the life-

history of the species had been studied either in its native

haunts or in suitable aviaries; therefore, for the cabinet orni¬

thologist to decry the work of the aviculturist who is helping

him to the truth, almost makes one wonder whether, where his

own species are liable to go to the wall, he really desires light

on the subject.


Apart from seasonal changes of plumage, we find also

changes in the colouring of the soft parts ; and, where these are

very marked, the summer and winter types are very liable to be

regarded as distinct species. The soft parts also become modified

in colour with age, as I proved in the case of Paroaria capitata,

the young of which had the eulmen of the beak and front of the

tarsi slate-grey, which colouring gradually disappeared as the

adult plumage developed, though some examples retain it longer

than others.


To complicate the study of birds yet more, we not only

find sexual differences, juvenile differences, and seasonal differ¬

ences, both in the plumage and the soft parts, but we meet

constantly with slight local modifications which the modern

cabinet-worker now regards as subspecies, and dignifies with a

place in the nomenclature. Unfortunately the students of bird

skins are not all agreed as to the rank of these localized forms,

as witness the article by Mr. P. R. I y owe, in “ The Ibis” for 1908



