182 Biology in America 



pear save for a fringe of timber along the stream bottoms, 

 giving place to the vast prairies of the west. New types of 

 animals also appear upon the scene. Squatting on his 

 haunches outside the entrance to his subterranean home the 

 prairie dog squeaks defiance at the passing traveler, and the 

 burrowing owl utters its shrill cry in protest at the pres- 

 ence of the intruder. Several species of ground squirrels or 

 gophers are characteristic members of the animal commun- 

 ity, some of which extend eastward across the Mississippi. 

 The black and white of the lark bunting is a conspicuous f ma- 

 ture of the landscape, while the magpie in his coat of green 

 and white lends color as well as noise to the cottonwood 

 groves along the rivers. The Great Plains form an inter- 

 esting ' * tension line, ' ' as the biologist calls it, * ' where east 

 is west and west is east and ever the twain shall meet. ' ' 9 The 

 eastern and western movement of the western and eastern 

 flora and fauna respectively is one of the most interesting 

 features of this area. The dicksissel, one of the sparrow 

 family, a characteristic bird of the Mississippi Valley, has 

 only in recent years ventured from his ancestral home across 

 the vast prairies to the west. Conversely the magpie appears 

 to be moving slowly eastward. The red-eyed vireo, whose 

 home is in the eastern United States, appears within recent 

 years to have followed the Missouri Valley westward, crossed 

 the Rocky Mountains and established itself in the northwest- 

 ern United States and British Columbia. 



An interesting suggestion as to how the migration routes 

 of various birds may have become established, many of which 

 are very devious and hard to explain, is to be found in the 

 route of this bird. Wintering in South America, it moves 

 northward in spring following the course of the Mississippi 

 River to near its headwaters, whence it turns northwestward 

 across mountains to its breeding grounds in the North. A 

 much shorter route lies west of the Rockies ; but inherited in- 

 stinct (or is it parental example?) carries the bird in the 

 path of its forefathers far from the course which is most 

 easy and direct. 



Another interesting case of recent extension of a bird's 

 breeding range is furnished by the bobolink, which is an in- 

 habitant of marsh and meadow land. With the settling of 

 the arid territory of the West, accompanied by its irrigation, 

 the bobolink is accompanying the western march of empire, 

 and settling itself in Nevada, Oregon and other western states. 



Between the Rockies and the Sierras lies the Great Basin, 

 scorched with the torrid heat of summer and frozen with the 

 icy blasts of winter, a land parched with endless drouth. 



With apologies to Mr. Kipling. 



