38 FKOM THE NIGEE TO THE NILE 



of rock with tail raised. Towards evening, when the noises 

 of day begin to die down and every sound through the rocky 

 places takes on a more sonorous tone, it is delightful to listen 

 to the chorus of these little rock-dwellers. There is always 

 a leader whose cue is taken up with great zest by all the 

 others ; the notes grow loud at first and then die away into 

 the stillness. 



It was not till we reached the vicinity of Lake Chad that 

 we found the pin-tail sand-grouse {Pterocles exustus), in- 

 habiting the sandy pasture that hes between the shore and 

 the wood country. 



The punctual habits of these birds are remarkable. 

 Every morning and evening at the same hour, batches would 

 fly high over our camp, suddenly to drop down with a sound 

 like a shower of spent bullets in the water, afterwards 

 returning the same way as they had come. Sometimes, in 

 the season of the harmattan, when their flight was not 

 discernible in the prevailing haze, its course could be traced 

 by their noisy voices, that sounded like the creak of rusty 

 springs set in motion. These birds might almost be called 

 crepuscular by nature, for should the night be moonlight, 

 they feed in the vicinity of the water, remaining there 

 till dawn appears. 



Before our expedition to Bornu and Lake Chad, next to 

 nothing was known of the birds of this part of Africa, for there 

 were only the small collections made by Denham and 

 Clapperton around Lake Chad in the year 1822-1824, which 

 resulted in the discovery of a large bustard (Otis denhami) 

 and a francohn (FrancoUnus dappertoni). The 800 speci- 

 mens which I collected have revealed the interesting fact 



