NATURAL HISTORY OF SOUTH AFRICA 



the sides of kloofs ; but the rat is an excellent 

 climber, and few bird's nests are safe from its at- 

 tacks. Again, the tree snake's diet is principally 

 the eggs and young of birds, and if these species 

 of snakes should be allowed to increase unduly in 

 numbers, the insectivorous birds, which are abso- 

 lutely essential in the economy of Nature, would 

 become almost extinct. The mungoose, it is true, 

 cannot pursue these snakes in their haunts among 

 the branches of trees, but it seeks out and devours 

 the eggs, which are usually deposited in crevices 

 amongst the roots of trees, under decaying leaves, 

 or brushwood, or in holes. Not a few of these 

 destructive tree snakes fall victims to the mungoose 

 when they descend to the ground, as they frequently 

 do in search of food, or to bask in the sun's warm 

 rays, and to absorb the heat from the sun-baked 

 earth. Mice and rats, however, constitute the 

 mainstay of the diet of the mungoose, and it should 

 be borne in mind that there are a considerable 

 number of species of rats and mice native to this 

 country, as well as otherswhich have been introduced, 

 such as the common barn rat and house mouse. 

 Rats and mice rear several families annually, con- 

 sisting of from five to ten at a brood. They begin 

 breeding at an early age, and the progeny of a single 

 pair of rats in a few years, if allowed to breed un- 

 checked, would amount to many millions. Rats 

 and mice have no redeeming qualities, so far as man 

 is concerned. True, they eat insects at times, but 

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