390 Mr Buxton, Animal ecology in Deserts 



desert birds are protectively coloiired as chicks and as adults, 

 but their eggs are in no way specially coloured and in general 

 resemble the eggs of related birds which do not breed in 

 deserts. 



It appears to have been overlooked that black animals form 

 a definite element in the fauna of the great palaearctic desert belt 

 which stretches from Marocco to the Gobi. Examples are a number 

 of the Wheatears {Saxicola melanoleuca, S. lugens, S. leucopyga, 

 S. monacha, S. tnorio, etc., all of them predominantly black, with 

 a greater or lesser amount of white). One might also mention the 

 ravens Corvus umbrinus and C. rhividurus (affinis). Among the 

 insects the coleopterous family Tenebrionidae is characteristic of 

 deserts in many parts of the world. Black tenebrionids, belonging 

 to no less than five sub-famihes (Erodiinae, Zophosinae, Tentyrinae, 

 Adesmiinae and Pimeliinae) are a very conspicuous feature of the 

 deserts of the palaearctic region from Marocco eastwards to Turkes- 

 tan, and to Sind. The great maj ority of these black forms are diurnal : 

 in these same deserts there occur a number of Tenebrionidae which 

 are not black: the majority of these are buff, or grey, or brown, and 

 these species are mainly nocturnal. Other sub-families of Tenebrio- 

 nidae occur in the deserts of Australia and America, and many of 

 these insects are black, but I do not know whether they are diurnal. 

 In the Orthoptera there is an example in the Phasgonuridae (Locus- 

 tidae) : in Algeria I took that remarkable insect Eugaster guyoni ; 

 this is a large stout locust, black and highly polished, with some red 

 prominences on the thorax. It is unable to leap, for its hind legs are 

 barely stronger than its forelegs, an unusual condition in this family. 

 This species also is diurnal and of course extremely conspicuous: 

 it is probably protected by its copious secretion of blood, or at 

 least one is tempted to suppose that this is the case. It is prob- 

 ably the case that none of these black animals are preyed upon 

 by larger animals: wheatears are extremely wary birds, which 

 perch on the very summit of some upstanding rock and are always 

 ready to dive under a stone at the approach of danger: ravens, so 

 far as one knows, act more often on the offensive than the defensive : 

 the tenebrionids are covered with an intensely hard exoskeleton, 

 and are probably often attacked by birds or lizards without 

 suffering harm: I say this because I have frequently taken speci- 

 mens of Adesmia and Pimelia with several legs or antennae missing, 

 or with dinted but unpierced elytrae. Granted that the black 

 creatures are in some way protected, and therefore not in need of 

 protective coloration, we do not in the least know why they are 

 black, a colour which must render them extremely hot in the desert 

 while the sun shines. To sum up, of course I admit that the majority 

 of animals which five in deserts are coloured protectively, but find 

 the protection much less efiicient than I had supposed. There is 



