Fig. 5. Occurrence of high (solid bold lines) and low (broken lines) M_sum for tips of phylogenies for summer and winter birds in this study. The numbers and letters at the ancestral nodes and branch tips refer to high M_sum (1), low M_sum (2), low T_CL (good cold tolerance; A), high T_CL (poor cold tolerance; B). Low and high M_sum and T_CL were determined from tips or nodes that fell outside of 95% confidence intervals from allometric regressions of logM_sum and logT_CL on logM_b for both raw data and phylogenetically independent contrasts.