KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 47. N:o 5. 27 



land. -But on the other hand not less than 27 species are distributéd from Easl Afrioa 



northwards to Abyssinia, and 5 more do the same but reach the Central African Lake 



district as well. The great ninnber of 22 species appear to be confined. to Somaliland, 



while 16 may be regarded as Somalibirds whieh also extend down into East Africa, and 5 



range from Somaliland and northward, resp. northwestwards. 



If the proportion in which the different zoogeographic elements of the fauna of the 



Guaso Nyiri district are represented, is expressed in percentages the following result is ob- 



tained: 



Widely distributéd birds (A. At) !>,o % 



Birds found as well south as nortli dt' the district in question in Kast, Africa 



(Ea, Ea Wc, Eni Sno) 21, i 



Birds found in East Africa proper and soutli of the same district (hut not further 



nortli: E, EWc, Es, Eni, Ez, EsWc) • 8,1 



Birds found in East-Africa proper and northwards beyond Somaliland (hut not 



south of the first mentioned district: Eno, Eno Wc) 26, o » 



Somali-birds confined to Somaliland, or partly ranging south in the eastern parts of 



East Africa, or partly extending nortli hut not south of Somaliland (S, Se, Sno) 34, u » 



From this it becomes very evident that the Somali-, resp. Northeastern fauna is 

 quite dominating in the Guaso Nyiri district. 



On the other hand it can be seen from the table that there are hardly any Western 

 affimties at all. Not counting those species which are widely distributéd all över the 

 continent there is not a single species which extends further west than into the Central 

 African Lake district. Of all other geographical groups 13 species range into the Lake 

 district and of the ni 6 are widely distributéd in East Africa (Ea Wc), and 5 range from 

 East Africa northwards to Abyssinia or beyond (Eno Wc). The remaining two are resp. 

 more southern (Es Wc), and typical of East Africa proper (E Wc). 



If these facts are compared with those recorded above concerning the species of 

 birds collected in the country between Nairobi and Meru borna it is plainly seen that the 

 difference is great. It is quite evident that the boundary line between the East- African 

 district s. str., and the Somali district is to be found just south of Guaso Nyiri as sharply 

 pronounced as such a boundary line ever can be on a continent where there is no moun- 

 tain range, or any other similar great obstacle for the distribution of the different forms. 



In the country through which this Expedition passed there was very little water 

 Not a single lake was visited, and the running waters were mostly small rivulets. The 

 swamps were mostly dry at the time, and their inhabitants had therefore moved to other 

 places. The number of waterbirds obtained is therefore small, and with addition of some 

 species with full certainty observed but not shot the number amounts only to 21 species, 

 although among them are counted some species which are not completely confined to 

 water but only water-loving like Motacilla vidua, or living in the rich swamp vegetation 

 like Centropus super ciliosus, and Pomatorhynchus minutus. It is evident that for water- 

 birds or water-loving birds the water is the main condition of life. They are consequently 

 able to exist where there is suitable water, and are otherwise more or less independent 

 of the conditions of the country in which the water itself is situated. If the water dries 

 up, the birds move away to some other place where there is some water suiting them. A 

 result of this is that waterbirds as a rule have a wide range, and this is proved by the 



