BIRDS AND HORTICULTURE 



having either animal or vegetable diet rear their 

 young upon food similar to that which they 

 themselves use. Gulls, Terns, Pelicans, Herons, 

 and Kingfishers are fish-eating birds, and bring 

 up their nestlings on fish. Hawks and Owls are 

 birds of prey, and feed their young on birds and 

 mammals. Insectivorous birds, as Cuckoos and 

 Swallows, feed on nothing but insects. Exclu- 

 sively graminivorous birds, such as Doves and 

 Pigeons, feed only on starchy seed materials. 



Birds that feed upon both animal and vege- 

 table matter usually feed their nestlings entirely 

 on insects, chiefly injurious kinds, as grasshop- 

 pers and cutworms. Many of our common 

 birds are of this class. Seed-eating birds, and 

 those that subsist on a mixed animal and vege- 

 table matter composed largely of hard material, 

 have powerful, muscular, grinding gizzards. 

 Food of this kind resists digestion and requires 

 to be broken up in the stomach. Birds that live 

 on insects and vertebrates that are soft and 

 easily digested have thin-walled, comparatively 

 weak, non-muscular stomachs.' Stomachs of 

 newly hatched nestlings are, in most cases, 

 merely membranous sacks, with comparatively 

 little muscular development, and can not assimi- 

 late anything but the softest, most readily di- 

 gested food. 



Many birds that are largely vegetarians feed 

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