My dear Sir

I have hardly ever received a note which has interested me more than y^r last;² & this is no exaggeration.

I had a few cases of birds perceiving slight changes in the dress of their owners, but y^r facts are of ten-fold value. I shall certainly make use of them, & need not say how much obliged I should be for any others about which you feel confident.

Do you know of any birds besides some of the gallinacæ which are polygamous?

Do you know of any birds besides pigeons, & as it is said, the raven which pair for their whole lives.

Many years ago I visited your brother who shewed me his pigeons & gave me some valuable information.³ Could you persuade him (but I fear he w^d think it high treason) to stain a male pigeon of some brilliant colour & observe whether it excited in the other pigeons especially the females admiration or contempt?

For the chance of y^r liking to have a copy & being able to find some parts which w^d interest you, I have directed Mr Murray to send you my recent book on Variation under Domestication.⁴

With cordial thanks believe me | yours sincerely | Ch. Darwin

P.S. I have somewhere safe references to cases of magpies, of which one of a pair has been repeatedly (I think seven times) killed, & yet another mate was always immediately found— A gamekeeper told me yesterday of analogous case.⁵ This perplexes me much. Are there many unmarried birds? I can hardly believe it.— Or will one of a pair, of which the nest has been robbed, or which are barren, always desert his or her mate, for a strange mate with the attraction of a nest, & in one instance with young birds in the nest? The gamekeeper said during breeding season he had never observed a single or unpaired Partridge. How can the sexes be so equally matched?

P.S. 2^d.— I fear you will find me a great bore, but I will be as reasonable as can be expected in plundering one so rich as you.—

P.S. 3^d | I have just received a letter from D^r. Wallace of Colchester about proportional numbers of the 2 sexes in Bombyxii & in this note, apropos to an incidental remark of mine, he stoutly maintains that female Lepidoptera never notice the colours or appearance of the male, but always receive the first male which comes, & this appears very probable— Says he has often seen fine females receive old battered & pale-tinted males.—⁶ I shall have to admit this very great objection to sexual selection in insects.—

His observations no doubt apply to English Lepidoptera in most of which, the sexes are alike. The Brimstone or Oran-tip⁷ w^d. be good to observe in this respect; but it is hopelessly difficult.—

I think I have often seen several males following one female—& what decides which male shall succeed? How is this about several males; is it not so?