SOME COMMON MAMMALS. 139 



creature, active on foot, progressing sometimes with side- 

 long leaps. 



The most interesting feature about the Stoat is its 

 change of coat from the red in summer to white in winter. 

 The tip of the tail remains black. The change is really 

 a change of fur. Here are two problems. Why the change 

 of coat ? And why the persistent black tip to the tail ? 

 We know that the Stoat, were it red at this season, would be 

 more readily seen upon the snow by its natural prey, which 

 thus would be warned in time. The whitening is a winter 

 adaptation in favour of the Stoat. In high altitudes, where 

 the snow lies through a greater part of the year, the Stoat 

 is always white (Fig. 46). 



The black tip is not so easily " explained." But it may 

 be a recognition mark amongst the members of the 

 species. Stoats attack rabbits, young hares, water voles, 

 and rats. Their depredations upon the poultry run and. 

 game preserve are notorious. They also climb trees, 

 taking eggs and young birds. Stoats have 5 or 6 young 

 in the spring. 



The Weasel is generally about the same size as the 

 Stoat, but the female is subject to considerable variation. 

 It is reddish brown above and white below. It may 

 always be distinguished from the Stoat by its short tail, 

 which is less than half the length of that of the 

 Stoat, and is of the same colour as the upper parts of 

 the body. Its neck is longer and the body is arched. 

 Sometimes the Weasel undergoes a winter change of 

 coat, becoming white. But this is only an occasional 

 occurrence. The Weasel has a litter of from 4 to 6 young 

 each year. 



The diet differs in important respects from that of the 

 Stoat. The usual prey consists of voles, rats, mice, moles, 

 and small birds. Weasels frequent farm buildings for the 

 sake of these vermin usually. They occasionally kill chicks 

 or ducklings, but it is generally admitted by those who 

 have given attention to the subject that the good done by 

 Weasels in killing young rats and other vermin more than 

 balances the mischief sometimes wrought in the poultry 

 yard (Fig. 47). 



