CHAPTER XX 

 THE FOOD 'OF ANIMALS— OMNIVOROUS MAMMALS 



Some account having been given of typical anima'ls which 

 feed on either animal or vegetable matter to a preponderating 

 extent, if not entirely, our attention is claimed by those forms 

 which are commonly called omnivorous. The term is not very 

 happy, for it implies a more largely varied bill of fare than 

 actually turns out to be the case with regard to many creatures 

 so designated. It is best, therefore, to interpret "omnivorous" 

 as meaning " feeding on both plant and animal substances ", the 

 proportion between the two varying greatly in different cases. 

 Even some of the highly -specialized carnivorous forms which 

 have already been described occasionally take a certain amount 

 of vegetable food, while on the other hand some of the confirmed 

 vegetarians may not be above swallowing a certain amount of 

 animal matter. Here, indeed, as elsewhere, it is impossible to 

 establish sharp boundary-lines, and one stage in the life-history 

 of an animal may affect one sort of food while during another 

 stage the nutriment may be quite different. The young of the 

 common House- Sparrow, for example, is fed largely on worms 

 and grubs, while the adult birds are notorious for the damage 

 they do to cultivated crops. And we have seen that in the case 

 of Mosquitoes and their kind there is even a difference between 

 the two sexes in the matter of food, for the female is endowed 

 with troublesome blood-sucking propensities, while the harmless 

 male subsists upon the juices of flowers and the like, though 

 perhaps there may have been a little exaggeration in this matter, 

 at any rate as regards some species. 



Space forbids detailed consideration of many omnivorous 

 animals, and it will only be possible to select a few specially 

 interesting examples for description. Beginning as in other cases 

 with the Vertebrata, or Backboned animals, we will take in 

 succession Mammals, Birds, Reptiles, Amphibia, Fishes, and the 



