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Black-tailed prairie dogs (Cynomys ludovicianus) have high dietary overlap with livestock, which can cause forage-centric conflicts between agriculture and conservation. However, research suggests prairie dog�livestock relationships may mimic historic prairie dog�bison relationships, perhaps due to enhanced forage quality on prairie dog colonies. It remains unclear how the strength of trade-offs between quality and quantity varies throughout the growing season, or the degree to which increased forage quality is caused by altered species composition versus altered plant physiology. To assess the effects of prairie dog herbivory on forage in northeast Wyoming, we collected samples on and off prairie dog colonies during June, July, and August 2016 for forage quality, and August 2016 for biomass. To isolate mechanisms affecting forage quality, we collected both composite samples of all herbaceous species, and samples of western wheatgrass (Pascopyrum smithii, PASM). For crude protein (CP), total digestible nutrients (TDN),�in vitro�true digestibility, and calcium, prairie dog colonies had significantly higher values than control sites (5-68% greater, all p-values < 0.05, except PASM-TDN: p = 0.15). The effects of prairie dogs on forage quality did not vary seasonally for PASM samples (all treatment*time p-values ? 0.1), but for composite samples, the effects of prairie dogs on CP and calcium shifted as the growing season progressed (treatment*time p < 0.01 and p = 0.02, respectively). There was no statistically significant difference in biomass between prairie dog towns (30.75 � 12.37 g/m2) and control sites (72.57 � 19.24 g/m2; p = 0.21) due to variability among sites; however, on average prairie dog colonies contained half the biomass of control sites. Our results demonstrate enhanced forage quality on prairie dog colonies is due to both compositional and phenological shifts associated with prairie dog herbivory, and that enhanced forage quality may help offset reduced forage quantity.