8 BULLETIN 1227, U. S. DEPARTMENT OF AGRICULTURE 
TABLE 1.—Quadrat study, giving weights of grasses clipped each fall from per- 
manent meter quadrats under the different conditions as stated, to indicate 
the amount of forage destroyed by prairie dogs at Coconino, Ariz., 1919-1922. 
Total- Rodent- Cattle- Quantity 
Kind of grass.1 protection grazed grazed destroyed 
area. area. area. [by rodents.? 
Western wheat grass: Grams. Grams Grams. Grams. 
BE ROE As cia Db ae a toe eas ee Bie, peers 100. 0 3 6.6 63. 2 
OD se sot AL oo, eS eee eee 117.1 24.3 8.7 92.8 
BOOTS mie ocd ob spits onus cepa ee em aE see eR SE 138. 8 22.6 6.7 116. 2 
ODA eh oars Scien eae oeicthe =e SERRE sO OCR Eee one 161.1 77.2 6.7 83.9 
Sand dropseed: 
oe ec a ee oe es ee a ae aes oa cr 164.6 (3) 4.6 164.6 
NODS bi 23 S382 2. Sea SE ee 32. 8 (3 (4) 32. 8 
NODA Boi 23. ose kde her ct ue ee ee eee eee ree 81.9 4 6.4 81.9 
1 7 eae SR aR ee EE er dv ieee pth tae tS 38. 7 3.7 6.1 35.0 
1 Blue grama did not occur in sufficient quantity to be taken into account. 
2 Obtained by subtracting amounts under rodent-grazed conditions from those under total protection. 
ae rodents concerned are chiefly prairie dogs; a negligible quantity of forage may have been taken by 
others. 
3 Trace. 
4 None. 
It is to be recalled that. the figures in Table 1 were obtained under 
controlled conditions, by actual weights, and that the amount shown 
as destroyed by rodents is undoubtedly somewhat less than would be 
the case had it been possible to keep a full number of prairie dogs in 
the rodent inclosure and to exclude them completely from the total- 
protection area. The figures indicate in very general but impressive 
terms a potential rate of damage which may be expected where 
rodent grazing takes place in the wheat-grass forage type under con- 
ditions similar to those of this experiment. The following state- 
ment. (Table 2) presents some of the results obtained under these 
conditions: 
TABLE 2.— Annual production of forage and its reduction per acre by prairie dogs. 
Destroyed by prairie 
dogs. 
Produc- 
Forage. tion in 
: pounds. 
Pounds. | Percent. 
Wiostomwheatierass.cots oa. ih. Soe e sh Leh ech ete eee: 1,153 794 69 
SUSE CT ee Se Se ae ne Semen COR EE = 709 701 ; 99 
adatet ses 3! lass ol hoes caus. oh eh -dehceorae abe oeen 1, 862 1,495 80 
The annual forage loss on a section of land in this forage type 
at the rate shown in Table 2 would be the impressive total of 479 
tons. Nowhere on the range, however, is this type the continuous 
vegetation cover, and in most of the region it occurs as comparatively 
small islands in the surrounding types. It should be pointed out 
also that the quantity of forage destroyed by rodent grazing does 
not necessarily represent the quantity actually consumed. Part of 
the loss is due to the reduction of vigor of many grasses through 
early spring grazing, which inhibits their growth and prevents them 
from producing the quantity of forage they otherwise would. Un- 
fortunately, no satisfactory quantitative data are as yet available 
which indicate the amount of this loss, Continuous clipping of the 
