Extended Data Fig. 1. Comparison of heart rate and body temperature between strategies relative to migration stages during day.

a-f, Mean heart rate and g-l, body temperature are shown as points during day across all migrants (orange) and all residents (dark green) centred on departure date from breeding site relative to initial departure (a,g), stopover (b,h) in fall, centred on arrival date in wintering site (c,i), centred on departure date from wintering site relative to spring departure (d,j), stopover in spring (e,k), centred on arrival date on breeding site (f,l). For all measurements over time (a,c,d,f,g,i,j,k,l), each single point represents the mean value across each overwintering strategy, with migrants centred and residents correspondingly assigned. The coloured solid line shows predicted heart rate and body temperature values for each strategy derived from a generalised additive mixed model, including individual measurements for each bird. Correspondingly coloured ribbons show the 95% confidence interval of those predictions. Blue-marked periods highlight the time when migratory birds reside in their final wintering grounds. Horizontal red arrows mark the first and last times when measures significantly differ between strategies. For migration stage-centered comparisons via linear mixed models (b,e,h,k), means are shown as colored squares with standard error bars (SEM). Bonferroni corrected statistical significance levels: *** = p < 0.001, ** = p < 0.01, * = p < 0.05, and ‘n.s.’ = p > 0.05.