Mr Buxton, Animal Oecology in Deserts 389 



scanty vegetation affords no cover and necessitates an underground 

 life. Some of the meteorological conditions of deserts have received, 

 I believe, no attention so far as their effect on the fauna is con- 

 cerned. The extremely low relative humidity, the sharp spell of 

 heat by day and of cold by night, the great heat of the stones and 

 soil on which some insects crouch and the effect of direct sunlight 

 on animals are among the problems which call for study. We know 

 indeed that they must have their influence on the desert fauna, 

 but we have no accurate knowledge of what that influence is. Much 

 might be learnt by exposing animals to one or other of these 

 conditions, using an adequate number of controls. 



Colouration of animals. 



We have all of us known from childhood that in the desert the 

 animals, the birds and the insects are coloured like the desert: any 

 desert fauna furnishes countless examples of this. There are, how- 

 ever, a few very disturbing facts, which, I believe, are not widely 

 known. The Gerbilles {Gerbillus, Meriones, Dipodillus, Tatera, etc.) 

 and the Jerboas {Jaculus, Alactaga) all appear to be perfect 

 examples of protective coloration, bub they are strictly nocturnal. 

 This is also true, I believe, of the Cape Jumping Hare {Pedetes) and 

 the jumping mice of the deserts of southern North America 

 {Perodipus, "Zapus) and the Spiny Mice [Acomys) of Sinai, etc. It 

 is difficult to explain the coloration of these animals unless we 

 suppose that it is of some protective value by moonlight. One does 

 not know from what foe the Gerbilles need to escape, unless it is 

 foxes- certainly in Mesopotamia and Persia owls were almost non- 

 existent in the desert, except the resident Little Owl {Athene noctua 

 subsp ) and in winber the Short-eared Owl; both of these owls feed 

 almost 'entirelv by dav. As I have said, the Gerbilles and Jerboas 

 are strictly nocturnal," not appearing at dusk or at dawn: at Qazvm 

 in N W Persia I lived for four months close to colomes of Menones 

 erythrourus Gray and M. hlacMeri lycaon Thos. Every night I was 

 out in the desert between sundown and 9 p.m., and I was often 

 about iust when the dawn was breaking, but I never once saw a 

 Gerbille except in the hours of darkness, when they were extremely 

 abundant, crossing the light cast by my lantern. Among the birds 

 the Cream-coloured Courser {Cursorius galhcus) is efficiently pro- 

 tected bv its colour and disruptive pattern so long as it crouches; 

 but when it runs the long legs raise the body from the ground and 

 cause it to cast an extremely conspicuous black shadow, i he See See 

 Partridge (Ammoperdix griseogularis) Ihonhami] is another example 

 of imperfect protection bv coloration: the bird is crepuscular, 

 hidina by day in holes under rocks. In the evening its movements 

 are betrayed' bv the long shadow it casts as the suns rays decline 

 and this in spite of its short legs. It is a curious fact that most 



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