ANIMALS— PHYSICAL ENVIRONMENT 87 



the water which they can obtain from dew, insects, 

 and the vegetation ; in this group fall the Houbara 

 Bustard (Chlamydotis undulata), the Chough Thrushes 

 (Podoces), the Larks Alsemon and Ammomanes, and 

 others. 



Certain birds inhabit the fringe of deserts, but 

 seem to be prevented from penetrating them because 

 they cannot dispense with drinking. The need for 

 a drink of water is in these cases a Hmiting factor 

 in their distribution. An excellent example is the 

 Black Partridge (FrancoUnus vulgaris), an abundant 

 bird in the Mesopotamian plain. It is never found 

 more than a couple of hundred yards from water ; 

 it is a lover of thick scrub, but where scrub occurs 

 far from water the Black Partridge cannot be found. 

 In California a somewhat similar case occurs. The 

 Desert Quail {Lophortyx gambeli) wanders out into 

 the desert to forage, but its real home is] in the 

 scrub along the banks of ^the California River : 

 it requires to drink every morning and evening. 



It is difficult to study the habits of bats. Cer- 

 tainly many desert-dweUing species visit water 

 regularly at the beginiy^ng of their evening flight, 

 but we have no reason to say that this is the custom 

 of desert bats in general. 



Many wasps and other Hymenoptera make long 

 flights to drink, and crowd any spot at which they 

 can obtain water : some species require also mud 

 for nest-building. In Mesopotamia one often ob- 

 served the Oriental Hornet {Vespa orientalis) drink- 

 ing greedily in mess-rooms, and drowning itself 

 in drinking-cups : this had a considerable hygienic 



