Wildlife communities in anthropogenically modified systems tend to simplify to biologically homogenous communities. While this process is well documented, the exact mechanisms driving the convergence of species in human modified systems is unclear. There are two competing ecological explanations for how species replace one another: (1) changes to the physical environment and (2) changes to competitive interactions. We investigated the mechanism through which gray squirrels are replacing fox squirrels in the longleaf pine savannas of the southeastern United States. We experimentally manipulated competition from gray squirrels in nine hardwood patches imbedded in longleaf pine savanna at the Jones Center at Ichauway in Newton, GA.
Results/Conclusions
Fox squirrels responded strongly to gray squirrel removal, increasing activity in the core of hardwood patches by 300% [Oakpre/treatment = 0.008 (CI = 0.004-0.015), Oakpost/treatment = 0.025 (CI = 0.016-0.32)]. Fox squirrels in control patches did not use the interior of hardwood hammocks [Oakpre/control = CI = Oakpost/controlCI = . Our experimental results support the hypothesis that human driven changes to competitive interactions are important drivers of biotic homogenization.