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, aswellas 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 
18 
