316 THE WATER-RAT OR WATER-VOLE. 



dens are placed above normal flood-level, a spate 

 of exceptional violence may reach the young ere 

 their mother has time to carry them away. Were 

 they totally unable to help themselves, such a flood 

 might lead to terrible havoc among the water-vole 

 population all up and down the river, and would, 

 in all probability, sweep away that narrow margin 

 which lies between extermination and the com- 

 parative prosperity of the species a margin which, 

 in wild life of every kind, is so narrow as to leave 

 little room for new foes. 



But, though apparently more advanced in at 

 least one respect as a creature of the water than is 

 the otter, the water-vole is by no means a complete 

 master of that element. How long can a water- 

 vole live under water ? Probably no longer than a 

 trained human swimmer. If flustered and hurried, 

 it is unable to remain totally submerged for more 

 than forty seconds, and, unlike the chicks of 

 moor-hens and other water-fowl, it never hides 

 completely beneath the surface. Its diving abilities 

 are developed just so far as to enable it to achieve 

 concealment by diving till it has reached some 

 point of safe harbourage, such as a bank-burrow, 

 the roots of willows, or dense rushes. Like the 

 otter, it will lie submerged when hunted, only 

 its nose above the surface, taking advantage of 

 any drifting cover, and almost invisible as its body 

 swings with the current. 



During heavy spates, when the rivers are bank- 

 full and the burrows flooded, the water-voles are 

 dependent for their lives upon ' playing 'possum ' 

 in this way. I have many times observed them at 

 it, swimming hurriedly from point to point, and 

 lying concealed at every patch of cover to watch 

 and listen. When one flood has succeeded another 



