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Prairie dogs are a controversial rangeland species due to their importance as ecosystem builders and as direct competitors with livestock for resources. Consumption and clipping of vegetation by prairie dogs can substantially reduce available forage for cattle throughout a growing season and alter plant communities on mixed-grass prairie ecosystems. Research has demonstrated the effect of prairie dog colonies on forage quality and quantity for livestock, however, comparisons of use patterns by cattle and prairie dogs are lacking. A study was initiated in 2014 near McLaughlin, SD to compare defoliation patterns of western wheatgrass tillers by prairie dogs and cattle over a growing season. The study site has four 500 acre pastures with varying levels of prairie dog occupation that are grazed from June to October by yearling cattle at stocking rates calculated to achieve 50% utilization. Two hundred western wheatgrass tillers, accessible only to prairie dogs on active prairie dog colonies, were randomly chosen and permanently marked with small, colored wire rings at the base of tillers. Two hundred western wheatgrass tillers were similarly marked in off-town sites that were only accessible to cattle. Height, number of leaves, and grazing status of each tiller were recorded weekly. Preliminary results showed average pre-graze and post-graze heights of western wheatgrass tillers were greater off-town than on-town. Both probability of grazing and frequency of grazing were higher on-town compared to off-town. The two herbivore species appear to utilize vegetation differently throughout the growing season which may cause a shift in how plants respond to grazing pressure.