Ɛpsilon

From A. C. Smith   25 June 1873

Yatesbury Rectory | Calne | Wilts

June 25— 1873

Sir

I must apologize for the liberty I take in writing, to you; but I am so anxious to get your opinion on a point which nobody (I think) can answer so well as yourself, that I make bold to intrude upon you—. If I seem to be taking an unwarrantable liberty, it is because I am so well assured that none else to whom I can apply have such stores of facts to draw their inferences from as yourself

I seek information regarding the Cuckoo, and its propagation and my enquiry is, as to the possible amount of influence which a foster parent may have on the young entrusted to it.

It is (I think) conclusively proved that the Cuckoos egg frequently resembles the egg of the bird in whose nest it is laid; (the Germans say generally, but English Ornithologists deny this, so I prefer to say “frequently”) and the question is, how comes this variation of colouring?1

We may (I think) affirm, though this too has been questioned; that the Cuckoo herself who lays the Egg has no choice or will in the matter; but is quite unconscious (as all other birds are) of the colour of the egg she lays— Neither does it appear to be a provision of Nature, for securing the acceptance of the egg by the foster parents; for they are found to accept eggs of any colour.

What then can be the solution of this mystery? I have given much thought to it for years, and my present impression is (but it is no more than an impression until it is corroborated by better authority) that perhaps the nestling may imbibe with the food provided by its foster parents, some taint of that foster parents peculiarities: I know not how the pigment overspreads the egg of any bird, ere it leaves the ovary, or whence that pigment is supplied; but I fancy that every species of bird feeds its young after its own special manner; and probably the Hedge accentor, the titlark, and the Wagtail2 do not feed their young on precisely the same diet; Can it be then that diet affects the growing bird, and influences its after actions in any way?

I am well aware that in an analogous case the bees, when they have unexpectedly lost their queen, and no royal brood exists, can manufacture a queen out of a worker egg, by feeding the privileged grub with royal food.

Moreover it is a prevalent notion (though this may probably be a popular error,) that children imbibe from a wet nurse more or less of that nurses disposition!!

But I need say no more, except to ask you to excuse my thus troubling you: and if I can persuade you to give me a very few words in reply, I shall know whether to pursue or abandon my present notions on this particular.

In the event of your kindly answering my enquiry, would you also state if I am at liberty to use your name and authority on the points, as I have long been discussing this question in the Zoologist—;3 but I will of course (if you so desire it) not mention your name at all

Yours very sincerely | (Revd) A. C. Smith

1
CD had discussed the instinct of cuckoos to lay eggs in other birds’ nests, and had reported observations that some cuckoos, particularly the Australian bronze cuckoo (now Chrysococcyx lucidus), preferred to lay in nests where the eggs were similar in colour to their own. He also noted that eggs of the Australian species varied widely in colour. See Origin 6th ed., pp. 212–14.
2
Hedge sparrows (or dunnocks, Prunella modularis); titlarks, more commonly known as meadow-pipits (Anthus pratensis); and wagtails (genus Motacilla).
3
Smith had first published on the coloration of cuckoo eggs in the Zoologist in 1868 (A. C. Smith 1868). He revived the topic in another article in the March 1873 issue of the journal (A. C. Smith 1873a), which brought a series of responses in the April, May, and June issues. In a final article (A. C. Smith 1873b), Smith presented his view that cuckoo nestlings acquired their ‘nurse’s nature’, perhaps by diet, so as to produce eggs of similar colour to those of their foster parents. Alfred Newton had published an overview of the debate in Nature, 18 November 1869, p. 74; it was reprinted in the Zoologist (May 1873, pp. 3505–10).

Please cite as “DCP-LETT-8950,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-8950