. Essentials of biology presented in problems. Biology. THE VERTEBRATE ANIMALS 307 should be welcomed by all thinking Americans. Without the birds the farmer would have a hopeless fight against insect pests. The effect of kiUing native birds is now well seen in Italy and Japan, where insects are increasing and do greater damage each year to crops and trees. Of the eight hundred or more species of birds in the United States, only two species of hawks (Cooper's and the sharp-shinned hawk), the great horned owl, the cowbird, and the English spar- row may be considered as enemies of man. The Engli
. Essentials of biology presented in problems. Biology. THE VERTEBRATE ANIMALS 307 should be welcomed by all thinking Americans. Without the birds the farmer would have a hopeless fight against insect pests. The effect of kiUing native birds is now well seen in Italy and Japan, where insects are increasing and do greater damage each year to crops and trees. Of the eight hundred or more species of birds in the United States, only two species of hawks (Cooper's and the sharp-shinned hawk), the great horned owl, the cowbird, and the English spar- row may be considered as enemies of man. The English Sparrow. — The English sparrow is an example of a bird introduced for the purpose of insect destruction, that has done great harm because of its relation to our native birds. Introduced at Brooklyn in 1850 for the purpose of ex- terminating the cankerworm, it soon abandoned an insect diet and has driven out most of our native insect feeders. Investigations by the United States Department of Agriculture have shown that in the coimtry these birds and their young feed to a large extent upon grain, thus showing them to be injurious to agriculture. Dirty and very prolific, it already has worked its way from the East as far as the Pacific coast. In this area the bluebird, song sparrow, and j-ellowbird have all been forced to give way, as well as many larger birds of great economic value and beauty. The English sparrow has be- come a national pest, and should be exterminated in order to save our native birds. It is feared in some quarters that the English starling which has recently been introduced into this country may in time prove a pest as formidable as the English sparrow. Geographical Distribution and Migrations. — Most of us are aware that some birds remain with us in a given region during the whole year, while other birds appear with the approach of spring, departing southwards with the warm weather in the fall of the year. Such birds we call migrants, while those that
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbiology, bookyear1911
