To J. J. Weir   14 June [1870]¹

My dear Sir

As usual I am going to beg for information. Can you tell me whether any Fringillidæ, or Sylviadæ erect their feathers when frightened or enraged?² I want to show that this expression is common to all or most of the families of Birds— I know of this only in the Fowl, Swan, Tropic-bird, Owl, Ruff & Reeve, & Cuckoo—³ I fancy that I remember having seen nestling birds erect their feathers greatly when looking into nests, as is said to be the case with young cuckoos. I sh^d much like to know whether nestlings do really thus erect their feathers? I am now at work on expression in animals of all kinds & birds; & if you have any hints I sh^d be very grateful for them, & you have a rich wealth of facts of all kinds.—

Any cases like the following: the sheldrake pats or dances on the tidal sands to make the sea-worms come out; & when M^r. St John’s tame sheldrake came to ask for their dinners, they used to pat the ground; & this I sh^d call an expression of Hunger & impatience.—⁴

How about the Quagga case?⁵

I am working away as hard as I can on my book,⁶ but good Heavens how slow my progress is.— I hope that ⁠⟨⁠you⁠⟩⁠ are well.—

Believe me | Yours very sincerely | Ch. Darwin.