LINES OF MIGRATORY FLIGHT 157 



recorded a number of species which were present 

 only during the rainy season, a condition that may 

 hold as well in other parts of Africa. 



In the northeastern section of the Congo Basin 

 Chapin, during observations that covered three 

 successive years, has recorded nearly forty species 

 of truly African birds which he considered more or 

 less migrant. Most interesting among these is the 

 pennant-winged night-jar (Cosmetornis vexillarius)^ 

 a remarkable species in which the adult male has 

 two of the inner primaries (the second and third) 

 greatly elongated, so that they measure two and 

 one half times the length of the bird from the end 

 of the bill to the tip of the tail. Though strictly 

 tropical in its range, this striking species migrates 

 regularly back and forth across the Equator twice 

 each year. From September to November it breeds 

 in the open country south of the equatorial forest, 

 from Angola and Lake Tanganyika to Damaraland 

 and the Transvaal. A few birds remain throughout 

 the season in the northern edge of the breeding zone, 

 but the majority migrate northward in February to 

 Uganda and the grass country adjoining the forest 

 on the north. Its movements correspond with the 

 seasonal appearance of termites in the two regions 

 concerned, so that in the activities of these insects, 

 which form a valuable food, we may see a reason for 

 the shifting in range on the part of the goatsucker. 



