... plentiful on the Rockies, and the accumulating information concerning them may, in a few years, accredit Colorado with having more kinds of birds than any other State. The mountains and plains of Colorado carry a wide range of geographic conditions,—a variety of life-zones,—and in many places there is an abundance of bird-food of many kinds. These conditions naturally produce a large variety ... — Wild Life on the Rockies • Enos A. Mills
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