12 BULLETIN 15 3, UNITED STATES NATIONAL MUSEUM 



In the southern part of the northern highlands a large number of 

 birds represented in the mountains of tropical Africa occur, making 

 the avifauna there distinctive from that of northern Ethiopia, par- 

 ticularly in the forested areas. Even as far south as Shoa, however, 

 the forest fauna is poor in many avian elements, common farther to 

 the south. Thus, there are no pittas or broadbills. Among the bul- 

 buls alone, so numerous in tropical Africa, we may note the absence of 

 such genera as Arizelociclila, Stelgidillas^ Atimastillas^ Bleda^ Ghar- 

 itillas, Andropadus, Stelgidocichla^ and Eurillas. We may recall the 

 absence of such typical mountain forest birds as Heterotrogon^ Illa- 

 dopsis, and Alethe, the lack of forest weavers of the subgenera Sy7n- 

 plectes and Phormoplectes, of Nigrita and Spermopliaga; of Linurgus 

 among the finches ; the paucity of caterpillar shrikes and of species 

 of Apalis. (PL 9.) 



Just as the northern and western highland area tends to become 

 faunally different in different regions, so too we may note local 

 changes in the southern and eastern Ethiopian highlands. Thus, the 

 plateau and mountains of British Somaliland contain a number of 

 birds not found in the Arussi-Galla highlands. As examples may be 

 cited Francolinus castaneicoUis ogoensis, Columha olivae, Turdus 

 ludoviciae, Oenanthe pliillipsi^ Pycnonotus somaliensis, and Rhyn- 

 chostruthus socotranus louisae. The last named is not so strictly a 

 highland bird as the others, but it appears to occur at considerable 

 elevations. Some birds characteristic of the Arussi-Galla highlands 

 are Francolinus castaneicoUis hottegl, CercoTnela scotocerca enigma^ 

 Cercomela dubia, Pinarochroa sordida erlangeri, and Gossypha soni- 

 Tufa donaldsoni. In general, the Arussi-Galla highlands have rela- 

 tively few endemic birds, as most of the forms found there also occur 

 in Shoa and even farther west and north. The endemic forms range 

 down to fairly low altitudes also. 



One feature of the altitudinal distribution of bird life in Etliiopia 

 that stands out clearly is that far more lowland birds range high up 

 the mountain slopes, up to 7,000 or 8,000 feet, than extend up to 4,500 

 feet in more equatorial portions of the continent. Birds that reach 

 their altitudinal limit at 4,000 feet in the mountains of Kenya Colony 

 may occur as high as 7,000 feet in Arussi-Gallaland. The reason 

 seems to be that in the Ethiopian highlands there is no dense band 

 of tropical mountain forest encircling the higher mountains, and, 

 consequently, there is no impassable ecological barrier to prevent the 

 birds of the surrounding savannah lowlands from extending their 

 ranges to relatively great heights. A direct consequence of this con- 

 dition is the lack of any clear demarcation of life zones in the north- 

 east African highlands. Thus, there are no bamboo zones or tropi- 

 cal rain forest belts, but merely rather indefinite zones characterized 

 as follows (fig. 3) : 



