Moult

I can’t resist photographing the the Tufted ducks whenever they visit the Glen Gardens boating lake. The white flanks of the males usually dazzle but this morning…

Even if I hadn’t read Edward Blyth on moulting at breakfast this morning I would have assumed this was the phase he was going through.

I know precious little about “the feathered tribes” and was startled at the complexity of moulting in birds. Edward the Influencer explains:-

from “Seasonal and Other Changes in Birds”, The Magazine of Natural History, Vol 9, 1836, reproduced in Darwin and the Mysterious Mr X, by Loren Eisely, Harcourt Brace Jovanovich, New York, 1979.

Numerous as are the writers in this department of zoology…it still appears to me, that the numerous and very diversified regular changes of plumage and general external appearance, observable in this interesting subclass of animals, have been hitherto very greatly and strangely overlooked, and that, in consequence, the many valuable physiological inferences deducible from their investigation have been quite lost to the purposes of science and of classification.

It is true that many naturalists have in so far attended to the mutations of plumage which some particular species undergo, as that they are able at once to recognize them in every  livery they assume; but the exact ages, and seasons, of molting; the precise nature of the general, or only partial change that is undergone, and the various accordances and dissimilarities observable between the changes of distinct species; the endless characters of agreement and difference, so important in pointing out affinities, in showing what apparently similar races could never be brought to hybridize together; would seem to have been passed over as unworthy of notice, as undeserving of particular investigation.

…It is to be remarked, then, that some species of birds (as, for example, the larks and starlings, the crows, the woodpeckers, and various others) molt the whole of their immature, 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 [Parus caudatus Linnaeus], Mecistura rosea) shed the primary feathers of the tail the first season, but not those of the wing: numerous other races (as all the modifications of the fringillisous and thrush types) molt 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 wagtails and pipits, Motacillinae, and most of the aquatic races) which regularly undergo another general molting in the spring; though in no instance, that I am aware, are the primary wing feathers shed more than once in the year; those of the tail, however, in some rare instances are; and the different coverts, together with the second and tertiary wing feathers, in most, if not all,  double-molting 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 molt in the autumn; and in other birds, again (as in various ducks), 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 already been mentioned to show that a wide field for observation is here open to the practical ornithologist.

There have been two pairs of Tufted ducks on the lake during human lock down but the chap pictured was on his own this morning.

Tree 39 · Martin’s Ravine

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