456 LAND ANIMALS 



and the sun bird, Nectarinia famosa, lives in the Karoo from Decem- 

 ber to April and in the Knysna and East London areas from May to 

 November. 33 



With the first rain, the vicissitudes of the dry season are over. In a 

 surprisingly short time the grass shoots forth, the trees and bushes be- 

 come green and blossom, and the animal life changes accordingly. 

 The wild life, which was assembled at water holes, scatters widely over 

 the steppe; with fine scent, it detects distant rains and is drawn to 

 them. In places where a few weeks before immense numbers of an- 

 telopes, elephants, and zebras were present on the South African 

 steppe, they now disappear; the large herds divide at this season into 

 flocks and families. 



The aestivating animals reappear. Everywhere, one hears the croak- 

 ing of the frogs, of which there was no trace before. Oviposition quickly 

 begins in the recently formed pools. Tadpoles hatch after an aston- 

 ishingly short interval and grow at a surprising rate under favorable 

 conditions ; for the water is warm and affords abundant food ; it teems 

 with crustaceans, especially phyllopods, and contains numerous insect 

 larvae. Enemies also are present in abundance, it is true, such as 

 predaceous water beetles which prey upon the tadpoles, and various 

 water birds which appear like magic as soon as the rain falls. The 

 surviving frog larvae shortly are ready for metamorphosis, and if the 

 brief rainy period comes to an end, may bury themselves in the mud 

 for aestivation as young frogs. 34 



The winged sexual forms of the termites and ants rise in clouds 

 from their nests. Butterflies emerge from their pupae. Gnats and flies 

 whose larvae develop in the water are soon present. The grasshoppers 

 (acridids) hatch in large numbers from eggs, which had been laid in 

 the soil and may have lain there for several years until the degree of 

 moisture necessary for development is reached. 35 A gay swarm of 

 flying insects (Hymenoptera, beetles, Diptera) gathers on the flower- 

 ing trees. The shorter the duration of the rainy season, the more the 

 development of insect life is compressed into a short period. A single 

 species of beetle may suddenly appear in enormous numbers, only to 

 disappear after a few days to be replaced by another. 36 Snails, too, are 

 awakened by the moisture and come forth from the soil. 



Conditions are different in the high steppes with cold winters such 

 as those of the North Temperate Zone — in southeastern Europe, central 

 Asia, and North America. In these steppes the dried grass is covered 

 with snow, and decays. All snails, insects, and spiders, all amphibians 

 and reptiles, and small mammals, hibernate. Many burrowing rodents 

 remain active, it is true, but feed on their stored food supplies; hamsters 



