HOW ANIMALS LEARNT TO CLIMB 105 



culty. Except in the case of the tree-kangaroo, a 

 considerable modification of the hind-foot into some- 

 thing like the palm of a hand, or an equipment of 

 sharp claws, to act like the nails in an Alpine climber's 

 boots and prevent slipping, is usual in the creatures 

 which excel in lateral climbing. The cat and the 

 bear, the lynx, stoat, ferret, and rat are all as yet 

 imperfect in this branch of their business. The 

 marten, on the other hand, excels even the squirrel 

 in this acrobatic feat, for the squirrel naturally seeks 

 to escape the marten or sable in this way, yet these 

 small carnivora make" the squirrel their principal food. 



Tigers probably refuse to climb because their weight 

 is so great as to make any fall dangerous to a limb. 

 The bears, of which the grizzly climbs little, would 

 run the same danger had not they acquired a special 

 facility for rolling up first their limbs, and then their 

 bodies, into something like the initial curve of a 

 collapsing hedgehog, which preserves the bones from 

 injury. A bear will voluntarily roll over almost pre- 

 cipitous rocks and pick itself up at the bottom no 

 worse for its fall. 



No animal with hoofs can climb a tree, though a 

 goat very nearly succeeds in this, and the writer has 

 seen a pig climb out of a sty over a paling of 

 boards six feet high, with interstices between each of 

 the boards, and three cross-pieces of wood. The pig 

 scrambled up just as a dog might, and when the fore- 

 feet were over the top of the fence, gave itself a hoist 

 and a wriggle and rolled over, dropping on its feet. 



The climbing birds seem past masters of their busi- 



