On Birds Dressing Their Feathers With Oil From A Gland

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Title:     On Birds Dressing Their Feathers With Oil From A Gland
Author: Thomas Garnett [More Titles by Garnett]

Mr. Waterton doubts ("Mag. of Nat. History," vol. v. p. 413) if the small nipple on the rump of birds is an oil-gland, or that birds ever oil their feathers with matter obtained from it; and he asks if any naturalist will say that he has ever witnessed this process, and if so how it is that the bird contrives to take this oil in its bill and how it manages to oil its head and neck? I will therefore state what I think I have witnessed, and trust to Mr. Waterton's forbearance if I am in error; yet I cannot help suspecting that Mr. Waterton's queries are (like those of Charles the Second to the Royal Society) more for the purpose of laughing at our ignorance than from any wish he has to obtain information, for I can scarcely suppose that so acute an observer can have failed to perceive everything perceptible on the point at issue.

I have just watched a Muscovy Duck go through the operation of preening and dressing its feathers, and it certainly appears obvious enough to me that this bird uses the gland on the rump for the purpose for which birds are generally supposed to use it. The bird erected the feathers on the rump so as to exhibit the gland very distinctly, and then, after pressing it with the bill, rubbed the under mandible and chin down to the throat upon it, and then, after drawing some of the feathers through the bill, rubbed the lower mandible and chin upon the back and scapulars, apparently to apply the oil which adhered to them, and then, turning its head back, it rubbed the crown and sides of the head and neck upon those parts which it had previously rubbed with the chin and under mandible. By this rubbing of the head and neck it is easy to perceive how birds can oil these parts if it be allowed that birds oil themselves at all.

I cannot see how we can explain this action of birds in relation to any other object. It certainly does not seem calculated to expel or disturb any vermin lodged there, and I remarked that it never occurred except when the bird had been applying its bill to the gland as above mentioned. However, Mr. Waterton, and anyone who doubts this oiling, may readily judge for themselves. Let them take a common duck, and shut it up for two or three days, so that it can have no access to water except for drinking, and at the end of that time let them turn it out, and allow it to go to a brook or pond; it will give itself a thorough ablution--ducking, diving, and splashing with its wings--and on coming out, will begin to dress and arrange its feathers, very frequently applying its bill to the gland on its rump. If this application is not for the purpose of procuring a supply of oil, perhaps Mr. Waterton will have the goodness to inform us what it is for, and what end this gland answers in the economy of the feathered tribes if not that which has hitherto been supposed. (June 30, 1832.)

[The end]
Thomas Garnett's essay: On Birds Dressing Their Feathers With Oil From A Gland

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