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Darwin Correspondence Project

From H. B. Tristram   1 July 1868

Greatham Vicarage | Stockton on Tees

1 July 1868

Dear Sir

I must apologize for my delay in replying to your enquiries, caused by my absence from home; as your question required the examination of my collections & notes. I have now great pleasure in replying to your kind letter.1

My views generally were expressed in Ibis. 1859. Vol. 1— pp. 429. seqq written before the publication of your work on the ‘Origin of Species’.2

I find that 26 species of Saharan birds are clothed in a protective colouring, which differs from the ordinary colouring of their respective congeners, & closely resembles the colour of the surrounding desert—a buff fawn colour. 13 of these belong to genera where the sexes usually resemble each other in plumage, which similarity is continued in the desert forms.

Of the 13 others, where the sexes ordinarily differ in plumage, 10 desert species shew a like distinction, but generally speaking the distinction is confined to the under surface of the bird, as the breast or belly, while the back & head have the same sand coloured hue.

Thus the black in the ♂ desert sparrow, Corospiza simplex (which is a true Passer) & in the Pterocles is confined to the throat or belly, & is not visible when the bird crouches for concealment.3

In 3 species only of the 13 are the sexes similar, though ordinarily differently coloured in the same genus—

I should add that in a group of desert birds which depend for their safety not on escaping observation, but on refuge in holes or crevices of rocks, the plumage is remarkably bright & conspicuous. Thus the bright blue of Monticola cyanea, & the lustrous black of Dromolæa leucopygia & Dro. leucocephala have been noticed by me—4

In all these cases the young plumage follows the ♀.

I enclose a list of the desert birds of North Africa marked by protective plumage—& remain | Dear Sir | Yrs very faithfully & obliged | H. B. Tristram


Birds of the Sahara with a protective desert colouring in both sexes.

Corospiza simplex
Erythrospiza githaginea5
Fringillaria saharæ6
Saxicola philothamna7
Sylvia conspicillata11
Drymoeca striaticeps13
Crateropus fulvus14
Otocorys bilopha15
Calandrella deserti16
Ammomanes isabellina
Rhamphocorys clot-bey.18
Galerida abyssinica19
Certhilauda desertorum22
Pterocles alchata23
Caesorius gallicus.27

Sexes similar when ordinarily different.

Erythrospiza githaginea
Saxicola halophila

Conspicuous & bright colouring in Rock birds

Monticola cyanea
Dromolæa leucura28
Lanius dealbatus29
Geronticus comatus.30

CD annotations

1.1 I must … of Species’. 2.2] crossed pencil
7.1 I should … & remain 9.2] crossed pencil
7.4 by me—] ‘This change of Habit—colour not being changed— [illeg] 2 [illeg] of nesting’ pencil
Top of letter: ‘K | 58’ blue crayon
1st list: figures 1 to 15 added before each genus name, pencil


CD’s letter has not been found; see, however, the letter from H. B. Tristram, 6 June 1868.
In Ibis 1 (1859): 429 (Tristram 1859–60), Tristram had written, Writing with a series of about 100 Larks of various species from the Sahara before me, I cannot help feeling convinced of the truth of the views set forth by Messrs. Darwin and Wallace in their communications to the Linnean Society, to which my friend Mr. A. Newton last year directed my attention, ‘On the Tendency of Species to form Varieties, and on the Perpetuation of Varieties and Species by natural means of selection.’ It is hardly possible, I should think, to illustrate this theory better than by the Lark and Chats of North Africa. Tristram referred to Alfred Russel Wallace, Alfred Newton, and CD and Wallace’s joint paper read before the Linnean Society in 1858 (Darwin and Wallace 1858), before the publication of Origin.
The desert sparrow is now Passer simplex. Pterocles is a genus of sandgrouse.
CD cited Tristram for information on Monticola cyanea and the two Dromolaea species in Descent 2: 172. Monticola cyanea, the blue rock-thrush, is a synonym of M. solitarius. Dromolaea leucopygia and D. leucocephala were probably what would now be considered one or more subspecies of Oenanthe leucopyga, the white-tailed wheatear. Oenanthe leucopyga has three subspecies, two of which, O. l. leucopyga and O. l. aegra, are normally found in Africa (the third, O. l. ernesti, sometimes overwinters there; L. H. Brown et al. 1982–2004, 4: 502–4). According to Tristam 1859–60, pp. 297–9, D. leucopygia was distinguishable from D. leucocephala by the fact that it did not have a white head; according to L. H. Brown et al. 1982–2004, 4: 502–4, all subspecies of O. leucopyga develop a white crown after the first post-nuptial moult.
Erythrospiza githaginea is now Bucanetes githagineus (trumpeter finch).
Fringillaria saharae, which Tristam thought virtually identical with Emberiza striolata, the house bunting, (Tristram 1859–60, p. 295), is now E. sahari subsp. sahari.
Saxicola philothamna is a synonym of Oenanthe moesta, the red-rumped wheatear.
Saxicola deserti, the desert chat, is now Oenanthe deserti homochroa, the desert wheatear.
Saxicola halophila, the salt-loving chat, is now Oenanthe lugens halophila, the mourning wheatear.
Saxicola homochroa, the solitary chat, is now Oenanthe deserti homochroa, the desert wheatear (see also n. 8, above).
Sylvia conspicillata conspicillata: the spectacled warbler.
Sylvia deserticola: the desert warbler, or Tristram’s warbler.
Drymoica striaticeps is a synonym of Scotocerca inquieta, the scrub warbler.
Crateropus fulvus is now Turdoides fulva, the fulvous babbler.
Otocorys bilopha, the desert horned lark, is now Eremophila bilopha, Temminck’s lark.
Calendrella deserti is probably now C. rufescens minor, the lesser short-toed lark.
Ammomanes isabellina, the desert lark, A. pallida, the pale desert lark, and A. regulus, the little desert lark (according to Tristram 1859–60), are probably now subspecies of A. deserti.
Rhamphocoris clotbey is the thick-billed lark.
Galerida abyssinica (the Abyssinian crested lark) is a synonym of G. cristata isabellina.
Galerida isabellina, the isabelline crested lark, is now G. cristata isabellina, the Sudan crested lark.
Galerida arenicola, the sand lark, is now G. cristata arenicola, the north-east Algerian crested lark.
Certhilauda desertorum, the bifasciated lark, is now Alaemon alaudipes, the greater hoopoe-lark.
Pterocles alchata is the pin-tailed sand grouse.
Pterocles arenarius is now Pterocles orientalis, the black-bellied sandgrouse.
Pterocles coronatus, the crowned sandgrouse.
Pterocles senegallus is the spotted sandgrouse.
Tristam meant Circaetus gallicus, the short-toed snake eagle (see Tristam 1859–60, pp. 283–4).
Dromolaea leucura, the black wheatear, is now Oenanthe leucura.
Lanius dealbatus, the pallid shrike, is now Lanius meridionalis algeriensis, the southern gray shrike.
Geronticus comatus is now G. eremita, the northern bald ibis. For advice on the species names in this letter, we are indebted to Mike Blair of the Ornithological Society of the Middle East.


Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.

Tristram, Henry Baker. 1859–60. On the ornithology of northern Africa. Ibis 1: 153–62, 277–301, 415–35; 2: 68–83.


On the coloration of 26 species of Saharan birds.

Letter details

Letter no.
Henry Baker Tristram
Charles Robert Darwin
Sent from
Source of text
DAR 84.1: 93–4, 97
Physical description
ALS 4pp †, encl 2pp †

Please cite as

Darwin Correspondence Project, “Letter no. 6262,” accessed on 22 September 2023,

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