THE EGYPTIAN DESERT AND ITS BIRDS. 243 



and then Wheatears (Saxicola monacha) watch the intruder from 

 the top of a boulder. At night the whistling note of the Barn- 

 Owl and the echoing boom of the Eagle Owl (Bubo ascalaphus) 

 may be heard, while Jackals steal out to make their way 

 towards the cultivated land. The crevices harbour countless 

 Bats which, silent during the day, fill the air with their twittering 

 as dusk falls, before, as at a concerted signal, they fly out from 

 every cranny in a cloud. 



A curious and rather awe-inspiring noise is sometimes heard 

 in these valleys at sunset. A low rumbling is heard which rises 

 to a vibrating roar reverberating from the hollow rocks and 

 lasting some minutes before it gradually dies away again. 

 Apparently this noise is caused by the slipping of the sand on 

 the steep slopes. At all events, the same noise on a small scale 

 is produced if one slides down one of these sand slopes. As 

 one proceeds, the whole face of the slope begins to move, and 

 gradually a vibrating humming sound rises beneath the sand in 

 a most uncanny way. Apparently these gorges at Abydos 

 were noted in ancient times for mysterious eounds, for Abydos is 

 described in an inscription of about 4000 b.c. as " the region of 

 bellowing." 



Between these cliffs and the cultivated land which borders 

 the Nile is, as has been said, a fringe of desert, and here there 

 may be a rather rich bird life. Even here, however, in the dry 

 stony wastes there is little to be seen, but where the moisture 

 and other conditions are suitable for the growth of scanty grass, 

 tamarisks, and other semi-desert plants, a number of birds find 

 a home. It is in these places that the Cream-coloured Courser 

 is met with in small flocks. These birds are not uncommon, 

 though perhaps they are often passed unseen — I have seen a 

 piece of desert covered with their footmarks, and yet have 

 seen nothing of the birds. They are somewhat shy, run with 

 great speed, and readily take wing when pressed. In flight 

 they are very conspicuous, owing to the black markings under 

 their wing. 



Another most characteristic bird is the Desert Lark (Certhi- 

 laucla alaudipes), which may be found singly or in pairs along 

 this fringing desert. It is a fearless bird, and delights the 

 traveller by its habit of fluttering up a few yards into the air and 



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