45 8 PRACTICAL ZOOLOGY 



Gnawing Mammals. -- Gnawing mammals are, on the whole, 

 injurious, since they include such notorious pests as the rabbits, 

 rats, and mice. Rabbits are vegetarians, feeding on leaves, 

 stems, flowers, seeds, buds, bark, and fruit. They damage 

 especially clover, alfalfa, peas, cabbages, and the bark of trees. 

 Young fruit, forest, and ornamental trees and shrubs in nurseries 

 are subject to injury from rabbits, and frequently the branches 

 and twigs within reach are cut off, or the bark is removed near 

 the base of the trunk, thus girdling the tree and causing its death 

 (Fig. 320). 



Mice feed principally on stems, leaves, seeds, bulbs, roots, and 

 other kinds of vegetation. A single field mouse devours in one 

 year from twenty to thirty-six pounds of green vegetation, and 

 a thousand mice in one meadow would consume at least twelve 

 tons annually. Damage is done to meadows and pastures, to 

 grains and forage, to garden crops, to small fruits, to nursery 

 stock, to orchards, to forests trees, and to parks and lawn? 

 (Figs. 321 and 322). 



' The rat is the worst mammalian pest known to man. 

 Its depredations throughout the world result in losses amount- 

 ing to hundreds of millions of dollars annually. But these 

 losses, great as they are, are of less importance than the fact 

 that rats carry from house to house and from seaport to sea- 

 port the germs of the dreaded plague." The amount of loss 

 due to rats in the United States is not known; in Germany the 

 loss is estimated at $50,000,000 per year. The losses in this 

 country are as follows : a large part of the crops of cultivated 

 grains is often destroyed by rats; " the loss of poultry due to 

 rats is probably greater than that inflicted by foxes, minks, 

 weasels, skunks, hawks, and owls combined "; rats are a serious 

 pest in game preserves, feeding upon the eggs and young of pheas- 

 ants, etc.; fruits and vegetables both before and after being 

 gathered are damaged by rats; and miscellaneous merchandise 

 in stores, markets, and warehouses suffers injuries second only 

 to that done to grains. Rats eat bulbs, flowers, and seeds in 



