DAMAGE CAUSED BY ANIMALS. 99 



the tops pointing downwards, so that the thick ends come up to 

 about 6 feet above the ground, whilst a second labourer binds on 

 the twigs firmly with two thin but well- tempered wires. The out- 

 lay is said to be as low as 9s. to 11s. 6d. per 1000 poles, and the 

 twig bundles last for eight to ten years, so that only one repeti- 

 tion of the process is necessary before the stems outgrow the chief 

 danger of the bark being peeled off. 



c. SMALL EODENTIA. 

 52. Damage done ly Mice and Voles. 



Among the little, gnawing enemies of woodlands, by far the 

 most important part is played by mice, occurring in two genera, 

 Mus and Arvicola, which do damage. 



. The genus Mus, the true mouse, is characterised by its pointed 

 head, large ears, and tail as long as the body. Of this genus only 

 the Wood mouse (Mus silvatieus) commits damage by devouring 

 seeds, whilst only occasionally causing injury otherwise by gnawing 

 the bark. 



The genus Arvicola, the vole, is characterised by a broad head, 

 small ears hidden in fur, short legs, and a short tail. Many 

 species of it are injurious in woodlands, viz. : 



The true Field-mouse (A. arvalis), which is fond of retreating 

 into the woods in autumn, where it can make itself very injurious 

 both by devouring seed and mast, and by gnawing the rind of 

 saplings and poles, chiefly those near the ground, as it is an indif- 

 ferent climber ; 



The Common Field-vole, or short-tailed Field-mouse (A. agrestis), 

 which does damage in a similar manner, but is a better climber ; 



The Bank-vole (A. glareolus), which does less damage in devour- 

 ing seed than by gnawing, often climbing to a considerable height 

 in order to reach the soft bark ; and lastly, 



The Water-rat (A. amphibius), the largest species, which always 

 lives below the ground, and damages roots by gnawing them, but 

 never occurs in large numbers. 



Mice and voles are always to be found in larger or smaller 

 numbers in woods and fields, migrating from these latter into the 

 nearest woodlands in winter. Mild winters and dry springs and 

 summers favour their increase (which, as is well known, is of 



