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Darwin Correspondence Project

From A. D. Bartlett   9 December 1867

Zoological Society’s Gardens, | Regent’s Park, | London, N.W.

Decr 9th. 1867.

My Dear Sir

In reply to your note1 I beg to say the name of the birds in question is the Knot (Calidris canutus)   I have kept eight or nine of them and out of this number only one put on any of the breeding or summer dress,2 while in the same cage two Turnstones (Strepsilas interpres)3 both assumed their breeding plumage in the Summer, all the birds appear equally well in health and condition, the Turnstones have now moulted into the winter garb, the coloured worsted rags &c shall be tried immediately.4

believe me to be | Yours faithfully | A. D. Bartlett.

Chas. Darwin Esq

CD annotations

Top of letter: ‘If the summer Plumage of the Knot, is the same in 2 sexes, we learn that the summer plumage is nuptial & common to the 2 sexes—as occurs with a multitude of Birds.—’5 ink


Letter to A. D. Bartlett, 9 December [1867].
CD referred to the bird by its older name, Tringa canutus, in Descent 2: 82, citing Bartlett on specimens in the Zoological Gardens in London failing to develop their summer plumage.
Strepsilas interpres is now Arenaria interpres (see Birds of the world 3: 515–16).
See letter to A. D. Bartlett, 9 December [1867].
These points are developed more fully in Descent 2: 81–2.


Birds of the world: Handbook of the birds of the world. By Josep del Hoyo et al. 17 vols. Barcelona: Lynx editions. 1991–2013.

Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.


On the summer, or breeding, plumage of birds.

Letter details

Letter no.
Abraham Dee Bartlett
Charles Robert Darwin
Sent from
Zoological Society Gardens
Source of text
DAR 84.1: 38–9
Physical description
2pp †

Please cite as

Darwin Correspondence Project, “Letter no. 5720,” accessed on 18 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 15