BIRDS OF ETHIOPIA AND KENYA COLONY 5 



trich must be regarded as originally Asiatic and only secondarily 

 African. As the large mammals of the steppes poured into Africa 

 with the attendant swarms of carnivores preying on them, the vul- 

 tures probably followed them from Asia. The marabou stork {Lep- 

 toptilus) probably did likewise. In fact, man}^ families of birds, 

 such as larks, pipits, and many of the finches, must have come into 

 Africa after the drying up had eliminated much of the forest that 

 originally covered the continent. This same reasoning could simi- 

 larly be applied to the cranes, bustards, sandgrouse, and other groups. 



The presence of a number of essentially Oriental types of birds 

 (such as Smithornis^ Pseudocalypfomena, Pitta, and Pseudochelidon) 

 in the forests of west Africa, and likewise of a number of mammals 

 of Indian or Malayan affinities, suggests that there must have been a 

 connection between the primitive African continental forest and the 

 woods of southern Asia. The drying up of eastern Africa with the 

 resulting disappearance of the forest there accounts for the fact that 

 these forms are now so widely isolated. The evidence, briefly touched 

 on in the preceding paragraphs, indicates that once the African Con- 

 tinent started drying up (fossil trees in present desert regions are 

 good evidence of drying) and began to be a land of limitless plains, 

 the path by w^hich much of the life now flourishing there came to 

 enter it was by way of northeastern Africa, that is, the Somali- 

 Ethiopian region. 



The general region of immediate interest to us is then one that 

 must be looked upon in two ways — as the original home of a num- 

 ber of birds, and as the area through which passed a far greater 

 number of forms now found to the southward. Some of these latter 

 birds remained, others went on ; some probably were changed, others 

 not, during their sojourn in Ethiopia. 



A very striking point that can not be satisfactorily explained in 

 the light of present knowledge is the number of genera of birds 

 found in northeastern Africa and in South Africa and not in be- 

 tween. All are lowland, or semilowland, forms, chiefly larks of the 

 genera Hetero^nirafra, GertMlauda, and Spizocorys, although one 

 is a ralline genus, Goturnicops, and one is a group of bustards, Heter- 

 otetrax. In addition to these, three other genera are found in ISIedi- 

 terranean Africa, or Eurasia, as well as in northeast and southern 

 Africa — Gcronticus (including Gomatihis), Gyps, and Ainmomanes. 

 Of these, Geronticus and Gyps are denizens of the higher parts of 

 the mountains ; Avmiomancs occurs lower down. These cases are not 

 comparable to the larger number of species or genera that range 

 from Eritrea to South Africa, including the intermediate areas of 

 eastern Africa; they are all cases involving an enormous geographical 

 break or gap. Their sheer number, especially in a single family like 



106220—37 2 



