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Darwin Correspondence Project

From Arthur Edward Knox   [c. March 1855–7?]1

–at an early hour, & I have often witnessed the arrival of birds from the south—2 I hope to be able to do something in this way next month. The contents of the stomachs of graminivorous birds shot in the act of arriving should be preserved (I apprehend by washing them in water and keeping the seeds, if any). These should be forwarded to you I believe without delay? If you have time perhaps you can let me soon have a line to refresh my memory on this point—

Your hint about waterfowl3 may perhaps serve as a clew to unravel a mystery which puzzled me when I was a boy.4 At any rate it strengthens me in the opinion I then formed on the subject. The wild mountainous district in the Western portions of the Counties of Galway & Mayo in Ireland are studded with numerous loughs some very large, & others of smaller size and at various elevations above the level of the sea. At the beginning of the present century I believe there were no pike in any of these waters— The genus salmo in all its varieties lorded it over the lesser tenants of the deep— Into one of the lakes, pike were introduced, (by a short sighted proprietor) where of course they rapidly increased— These “freshwater sharks” a few years afterwards appeared in a distant lough which had no connection by any stream with the former—in fact was at the other side of a ridge of mountains. The pike were at first very small. How did they get there? I always fancied that the cormorants which used to come up from the sea to fish on the lough & used occasionally to visit the lesser ponds & even distant mountain pools, had a hand, or rather a foot, in it. Besides the pike-spawn which might have adhered to their legs and palmated toes, these birds, which have enormous gullets, might easily disgorge the contents of their first stomach on finding more acceptable prey than what it already contained—

I fear that I have tired your patience, but like all enthusiasts I am apt to override my hobby— Ever my dear Sir yrs very faithfully | A. E. Knox

CD annotations

crossed pencil
‘In a subsequent letter he speaks as if his memory was very doubtful upon whole subject’ added pencil
‘Does not know whether cormorants really do’added pencil
On first page: ‘18’5 brown crayon, circled brown crayon


Dated with reference to CD’s preoccupation with the dispersal of seeds and ova by birds and other means during the years 1855–7. Knox’s reference in the letter to the return of migratory birds indicates that the month was probably March.
Knox was a knowledgeable bird-watcher and author of ornithological books. CD read his Ornithological rambles (Knox 1849) in July 1852 (Correspondence vol 4, Appendix IV, 128: 2). CD also had a proof copy from a later edition (2d ed. 1850; 3d ed. 1855) of one of Knox’s chapters, entitled ‘Migrations of small birds’, in which Knox described the departure and arrival of migratory birds in southern Britain (Darwin Pamphlet Collection–CUL). Knox had made the point that many of the migratory birds arriving in Britain were seed and grain eaters (Knox 1849, p. 77).
Waterfowl figured prominently in CD’s account of the geographical distribution of animals and plants, particularly with regard to the transport of seeds in their gullets and in mud adhering to their feet.
Knox’s childhood was spent in County Wicklow, Ireland (Modern English biography).
CD’s portfolio number 18 contained his notes on geographical distribution. The information in this letter, however, was not used in either Natural selection or Origin, perhaps because Knox subsequently doubted his observations (see CD annotations, above).


CD has suggested an explanation of how pike were introduced to a remote lake in Ireland by cormorants [carrying pike spawn on their feet or in their gullets].

Letter details

Letter no.
Arthur Edward Knox
Charles Robert Darwin
Sent from
Source of text
DAR 205.2: 243
Physical description
2pp inc †

Please cite as

Darwin Correspondence Project, “Letter no. 1624,” accessed on 18 June 2018,

Also published in The Correspondence of Charles Darwin, vol. 5