| This research investigates whether black-tailed prairie dog populations are food limited at their northernmost range extent. A BACI experiment used food supplementation, while accounting for natural food variation, to test whether increased food positively impacted body condition, survival, reproduction, density and expansion. Experimental results did not support food limitation. Reproduction and density increased from 2008--2009 but remained similar between control and treatment plots. Correlations between vegetation biomass and density suggest that natural food availability in 2008 may have driven population growth into 2009. Percentage of edible vegetation varied between 2008-2009, raising the question: are prairie dog populations food limited in some years but not others? A negative correlation between winter survival and summer density, suggests internal regulation through density-dependent mortality. Greater overwinter survival than summer may be related to differences in predation pressure. Colony expansion was greater in the absence of food supplementation, suggesting food scarcity drives expansion. |
