SPECIAL PRECAUTIONARY HABITS 325 



As mentioned in a preceding paragraph, certain forms endowed 

 with the power of rapid movement are comparatively safe when 

 feeding in places from which a wide outlook is obtainable, and 

 this may be flat or undulating country, such as is favoured by 

 giraffes, many antelopes, wild horses, kangaroos, and ostriches, 

 or it may be of the mountainous rocky character affected by wild 

 sheep and goats, conies, baboons, and many other creatures. 

 Even where the powers of locomotion are not very extraordinary, 

 open places afford comparatively safe feeding-ground if a suitable 

 retreat is close by. Young Rabbits, for example, commonly feed 

 quite close to the mouth of their burrow, into which they imme- 

 diately disappear on the least alarm. Similarly arboreal forms 

 which feed to some extent on the ground, as is the case with a 

 number of Old- World monkeys, are pretty safe so long as trees 

 are at hand. This naturally suggests the next case to be con- 

 sidered, i.e. the arboreal or tree-inhabiting habit as a means of 

 protection. 



Arboreal Animals. — Several causes have had to do with the 

 evolution of climbing animals, and the remarks already made in 

 reference to the nocturnal habit (see p. 318) are equally applicable 

 here. Such an infinite variety of animals exist, and they increase 

 so rapidly, that the struggle for existence is exceedingly keen, and 

 every possible kind of food is liable to be commandeered. And 

 since (see p. 164) practically all animals are dependent on plants 

 either directly or indirectly, it would be extraordinary if woods 

 and forests had not attracted a large population, which has be- 

 come more or less specialized in accordance with the exigencies 

 of an arboreal life. The following remarks made by Bates (in 

 The Naturalist on the Amazons), in reference to the animal 

 population of the virgin forests of South America, forcibly illus- 

 trate this point. After speaking of certain climbing plants, he 

 says: — "The number and variety of climbing trees in the Amazon 

 forests are interesting, taken in connection with the fact of the 

 very general tendency of the animals also to become climbers. 

 All the Amazonian — and in fact all South American — monkeys 

 are climbers. There is no group answering to the baboons of 

 the Old World, which live on the ground. The Gallinaceous 

 birds of the country, the representatives of the fowls and pheasants 

 of Asia and Africa, are all adapted by the position of the toes to 

 perch on trees, and it is only on trees, at a great height, that they 



