Linear mixed models with 95% confidence intervals between size difference and behavioral score difference of Rusty Crayfish (Faxonius rusticus) and Calico Crayfish (Faxonius immunis) pairs from location-specific models of our two study regions, Illinois (IL) and Wisconsin (WI). Negative size difference indicates F. rusticus was larger than F. immunis. Negative score difference indicates F. rusticus behaved more aggressively than F. immunis. Both models include random effects for individual crayfish used in pairs to account for repeated observations on the same organisms, and the Wisconsin model includes a non-significant fixed effect for reproductive form difference that is not plotted.