XXX 
TAILS AND WINGS AS NUPTIAL LIVERY 
The ends of birds, like their limbs (wings and legs), 
are strangely modified ; the variations of the tails of 
some birds which flourish in Eastern Ethiopia are worthy 
of consideration. 
The quill feathers of a bird’s tail are called rectrices, 
or steering feathers, on account of their action in 
directing flight. The quills of these feathers are 
crowded on a narrow base, which causes them to present 
a fan-shaped arrangement. The normal number of 
rectrices is six pairs ; a few birds have ten or eleven ; 
several nine, eight or seven pairs ; and many five pairs. 
The reduction in number is brought about by the 
atrophy or disappearance of the outer pair or pairs. 
The number of rectrices differs among birds of closely 
allied species, and even in the cock and hen of the same 
species. For example, the peacock is furnished with ten 
and the peahen with nine pairs. The variation in the 
shape of the tail feathers is very great and is a fact well 
recognised. 
The profusion of bird life along the Nile Valley and 
around the lakes of Central Africa is wonderful, and so 
is its variety. Some of the biggest birds living on the 
earth to-day may be seen here. Ostriches, bustards, 
storks, cranes, secretary birds, eagles, vultures, herons, 
and pelicans. Size always impresses. Many of the 
smaller birds, such as bee-eaters, rollers, ibis, sun- 
367 
