Understanding limiting factors affecting population growth for imperilled species is crucial for conservation
and management. This research investigates whether black–tailed prairie dog (Cynomys ludovicianus)
populations are food limited on their northernmost range extent. We measured background vegetation
rates and used food supplementation in a ‘before–after–control–impact’ (BACI) design to test whether
increased food positively impacted prairie dog population density and colony expansion. Experimental
results did not support food limitation. Overall, density increased from 2008 to 2009 but remained relatively
similar between control and treatment plots. Correlations between natural, non-supplemented
vegetation biomass and prairie dog density suggest that natural food availability in 2008 may have driven
population growth into 2009. Natural food availability was highly variable among years and prairie dog
densities may be impacted by food scarcity in some years but not others. Colony spatial expansion was
greater in the absence of food supplementation, suggesting food scarcity may drive colony expansion.
This research has important implications for the conservation and management of prairie dogs and species
that depend on them such as reintroduced black–footed ferrets (Mustela nigripes) in Canada and
other populations across their range.