Factors contributing to the expansion of prairie dog (Cynomys spp.) colonies are poorly understood. Models simulating expansion of fossorial mammal populations interacting with the physical environment have shown mixed results. Data of burrow locations, burrow status, entrance type, aspect, and other characteristics were collected over a 4-year period on three study colonies. Several 50 m x 50 m plots were either mowed or burned near the periphery of the 3 colonies to determine the effects of these treatments on colony expansion. Spatial point patterns of burrows were analyzed for the post-treatment period. The overall orientation of new burrow locations was also examined. These analyses dealt exclusively with active burrows since numbers of active burrows are highly correlated with population density. Chi-square analysis suggested that burrows tended to be clustered. Directional analysis showed that colony expansion was oriented towards the treated plots 1 and 2 years after the treatments. K-function plots showed clustering at distances of 5.0 – 7.0 m. These analyses show that the fire and mowing treatments influence colony expansion. Our results contribute to our current knowledge of the factors both promoting and constraining the expansion of reintroduced prairie dog colonies, and may lead to more effective management of prairie dog colonies following reintroduction.