THE FOOD OF THE OTHER LAND ANIMALS 85 



insects, worms, etc. The sea snakes, with much the same 

 habits as the large tropical eels though usually more helpless 

 on land, are fish eaters, and all are poisonous. The terrestrial 

 snakes and the tree snakes, many of which are very venomous, 

 feed chiefly on vertebrates, including other snakes; some eat 

 eggs, and the smaller ones eat insects. The fresh water snakes 

 eat frogs, fish and other aquatic animals. Rattlesnakes feed 

 only on warm-blooded animals, the eastern diamond-back, for 

 instance, almost exclusively on cotton-tail rabbits. 



The land tortoises, a few terrapins, and some of the marine 

 turtles are vegetable feeders, but most turtles are carnivorous, 

 feeding on fish, frogs, insects, and other small animals. Our 

 common snapper often bites the feet off of young ducks. 



As a group, the birds are set apart from all the other verte- 

 brates by their superior method of locomotion, combined with 

 their superior vision. Small birds are preeminently destroyers 

 of insects, which they catch in the air like the flycatchers, 

 swallows and goatsuckers, pick off the leaves like the vireos 

 and most warblers, search for on the ground, like most thrushes, 

 water-thrushes, starlings, etc., dig out of wood, like the wood- 

 peckers and wood-hewers, extract from flowers, like the hum- 

 ming-birds, find concealed in the crevices of bark, like the 

 creepers, or even pursue under water, like the dippers. 



Some show decided preferences, like robins for earth-worms, 

 starlings for millepeds and flickers for ants, though robins and 

 flickers eat many t>pes of insects and even fruit, while king- 

 birds, hke phoebes and other of the larger flycatchers, are 

 very fond of young fish. But by no means do all small birds ex- 

 ist entirely on insects. There are many seed and fruit eaters 

 among them, especially among the finches or sparrows, though 

 these often feed their young on soft insects, and many birds 

 normally or chiefly insectivorous will subsist on vegetable 

 material if forced to do so. 



The larger birds tend more toward segregation into vege- 

 tarian and carnivorous types, both inclining toward further 

 specialization along particular fines. The pigeons, parrots, os- 



