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Darwin Correspondence Project

From J. J. Weir   14 August 1872

Accountant and Controller General’s Office, | H. M. Customs.

14th August 1872

My Dear Sir

I have thrown together an observation or two which may prove amusing, but I trust you will not deem it worth while even to acknowledge the receipt of this communication.—

I have had a further illustration in my aviary of the objection male birds entertain towards any others, which in the nuptial plumage, are colored in the same manner.—as themselves.1

The Spiza cyanea is in the breeding plumage a beautiful blue bird, The Spiza ciris has this color confined to the head only.—2

My Spiza cyanea, generally a very quiet bird, attacked the Spiza ciris, & completely scalped his blue head.—3

The Ciris however survived although it appears the skull is exposed, he even resumed his song after a few days, & afterwards remained unmolested

I was at the Zoological Gardens several days lately, & saw what I believe you are aware of, six young of the New Zealand Shelldrake, Tadorna Variegata,4 these all had the black head of the male bird, & were in all respects similar, they are however at this time beginning, at least the

CD annotations

1.1 I have … communication.— 1.3] crossed pencil
4.1 My … head.— 4.2] double scored pencil
6.1 I was … similar, 6.3] crossed pencil
Top of letter: ‘Descent of Man | J. Jenner Weir’ pencil


Weir and CD had corresponded at length on sexual selection in birds. For Weir’s previous observations on this point, see Correspondence vol. 16, letter from J. J. Weir, [before 3] March 1868.
Spiza cyanea (now Passerina cyanea) is the indigo bunting; S. ciris (now P. ciris) is the painted bunting.
CD added this information to Descent 2d ed., p. 412.
Tadorna variegata, the paradise shelduck, is native to New Zealand. The female has a white head. Weir refers to the Zoological Gardens in Regent’s Park, London.


Hostility of birds toward others with same colour;

nuptial plumage.

Spiza cyanea and Spiza ciris.

Letter details

Letter no.
John Jenner Weir
Charles Robert Darwin
Sent from
H.M. Customs
Source of text
DAR 88: 177–8
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 8470,” accessed on 23 July 2019,

Also published in The Correspondence of Charles Darwin, vol. 20