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Darwin Correspondence Project

From G. R. Gray   8 April 1868

British Museum

8th. April 1868

Dear Sir

I must trouble you with a line to say that the difference between the sexes of the Ibis rubra is, that the female is smaller than the male.— It is stated, that the bird is three year old, before it assumes the Scarlet plumage.1

Yours faithfully | G. R. Gray

C. Darwin, Esqre.


Ibis rubrais a synonym of Eudocimus ruber, the scarlet ibis (see letter from G. R. Gray, 2 April 1868 and n. 1). For more on plumage variations and size difference in the scarlet ibis, see Hancock et al. 1992, pp. 147–9.


Difference between sexes of Ibis rubra; change in plumage.

Letter details

Letter no.
George Robert Gray
Charles Robert Darwin
Sent from
British Museum
Source of text
DAR 84.1: 92
Physical description
ALS 1p

Please cite as

Darwin Correspondence Project, “Letter no. 6105,” accessed on 25 March 2023,

Also published in The Correspondence of Charles Darwin, vol. 16