NATURAL HISTORY OF SOUTH AFRICA 



bird leaves the nest its wings are usually sufficiently 

 developed to enable it to make short, uncertain flights. 

 All birds moult in the autumn. Moulting does not 

 take place until the breeding season is over. The 

 wing feathers of altricial birds are shed so gradually 

 that flight is not seriously interfered with. With 

 swimming birds, however, the reverse is the case. 

 They shed all their wing feathers at the same time and 

 become flightless. When the moulting season ap- 

 proaches they resort to secluded lagoons, lakes, rivers, 

 bays, etc., where they can live in comparative security 

 on the water while their new wing feathers are 

 growing. 



When feathers are plucked out by accident, others 

 grow. When the wing or tail feathers are cut, the 

 bird does not get another set until the old ones are 

 shed at the usual moulting season. The male bird 

 is, as a general rule, more handsome than the female. 

 The painted snipe {Rostratula capensis) is one of the 

 exceptions. With some species of birds the plumage 

 is similar in both sexes. Climate affects the colour 

 of birds' plumage more or less profoundly. Many 

 species of birds are extensively distributed. A species 

 which inhabits the more or less arid portions of the 

 country will be noticed to be paler in colour than 

 examples of the same species inhabiting humid dis- 

 tricts. Several degrees of variation may often be 

 observed in birds of the same species. This has given 

 rise to subspecies. Sometimes the variation is slight, 

 and at other times it is very pronounced. The climate 

 and food supply affect the size of the bird, as well as 



234 



