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UNITED STATES DEPARTMENT OF AGRICULTURE 



DEPARTMENT BULLETIN No. 1227 



Washington, D. C. ▼ August 10, 1924 



DAMAGE TO RANGE GRASSES BY THE ZUNI PRAIRIE DOG. 



By Waltee P. Taylor, Biologist, Division of Biological Investigations, Bureau 

 of Biological Survey, and J. V. G. Loftfield, Assistant Ecologist, Carnegie 

 Institution of Washington. 



CONTENTS. 



Page. 



Introduction 1 



Vegetation affected 3 



The Coconino experiment 4 



The Williams experiment 9 



Page. 



Some grazing relations of prairie dogs__ 11 



Summary and conclusions 13 



Literature cited 15 



INTRODUCTION. 



That native rodents cause heavy losses both in cultivated crops and 

 in forage plants on the pasture and range has long been recognized. 

 Indeed, after a careful calculation, the Biological Survey has con- 

 servatively estimated the losses in crops in the United States at 

 $150,000,000 annually, and in forage plants on the open range at a 

 like sum — a total annual loss of $300,000,000 from this source (Nel- 

 son, 1918, p. 2, and 1919, p. 5; Taylor, 1920, p. 283; Bell, 1921, p. 

 423). 1 Determinations under controlled conditions of the actual 

 damage done by rodents, either in cultivated crops or on the open 

 range, are, however, almost wholly lacking. The first paper dealing 

 in a precise manner with such damage is that of W. T. Shaw (1920) ,* 

 who made a determination of the destruction of wheat by the Colum- 

 bian ground squirrel (Citellus columbianus Ord) in eastern Washing- 

 ton. No comprehensive published results dealing quantitatively with 

 rodent damage on the open range have been seen. 



The difficulties in the way of this kind of experiment, while not 

 small, are by no means insurmountable; and it is believed that esti- 



1 Literature references and numbers in parenthesis refer to citations in " Literature 

 Cited," page 15. 



Note. — This bulletin is a report on a cooperative undertaking between the Biological 

 Survey, the Carnegie Institution of Washington, the Forest Service, and the Arizona Agri- 

 cultural Experiment Station to ascertain quantitatively the destructiveness of prairie dogs 

 to stock ranges. It is for the information of stockmen and others interested in the 

 control of rodent pests of the range. 



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