DAMAGE TO RANGE GRASSES BY THE ZUNI PRAIRIE DOG 13 



destruction of the range grasses over great areas is to be prevented, 

 these campaigns must be increased in scope and number. 



Careful attention to the plants eaten in the tall-grass and short- 

 grass forage types at Coconino, Williams, and Seligman, Ariz., 

 has shown conclusively that prairie dogs here consume only the 

 plants eaten by cattle and do not touch plants which cattle find un- 

 palatable. Hence these rodents compete directly with cattle for the 

 usual forage plants of this region. 



Not only do the rodents eat the same grasses, but they take them 

 in the same order of preference that cattle do. At Coconino, for 

 example, both eat the grasses in the following order: Dropseed, 

 wheat grass, blue grama. At Seligman both cattle and prairie dogs 

 grazed the Eussian thistle (Salsola pestifer) when it was young and 

 tender, but when old and tough neither would touch it. Prairie 

 dogs can graze the forage much more closely than cattle, and, there- 

 fore, are able to subsist where cattle can not and are far more de- 

 structive to valuable range plants. 



As previously suggested, the prairie dog does much more damage 

 to the range during seasons of drought than at other times. Whole- 

 sale poisoning of the rodents may well increase the forage in certain 

 instances sufficiently to permit the cattleman to carry his stock 

 through the dry period without loss. 



So far as these experiments now indicate, the prairie dog does not 

 possess a single beneficial food habit ; nor is there any argument, so far 

 as available facts or figures indicate, against its complete eradication 

 on all grazing ranges. The data here presented show conclusively 

 that the comparatively small expense of eradication is more than 

 justified. 



In many overgrazed areas, apparently, total eradication, of prairie 

 dogs and reduction in the number of cattle per unit area will be 

 necessary if the forage crop is to continue profitable. Almost anyone 

 can realize the serious damage done when the forage plants are ut- 

 terly destroyed and vast areas rendered worthless ; but many stock- 

 men do not properly appreciate the constant heavy losses to which 

 they are subjected by prairie dogs through decreased carrying capac- 

 ity of the range, even where the grass appears to be maintaining 

 itself. 



SUMMARY AND CONCLUSIONS. 



To determine quantitatively the character of prairie-dog damage 

 to the range in northern Arizona and the principal forage types 

 affected, two sets of experimental inclosures have been established, 

 one near Coconino, in the wheat-grass forage type; the other near 

 Williams, in the blue-grama type. Three plots were selected in each : 

 (1) One subject to cattle (or cattle and prairie-dog) grazing; (2) one 

 to prairie-dog grazing only; and (3) one protected from all grazing. 

 Grasses from meter quadrats on the plots were measured, charted, 

 clipped, and weighed each year. 



Eesults of four years' experiments at Coconino show that prairie 

 dogs destroy 69 per cent of the wheat grass and 99 per cent of the 

 dropseed, or 80 per cent of the total potential annual production of 

 forage. Eesults of one year's experiments at Williams show that the 



