Fig. 1. Seasonal changes in physiological parameters and behaviour (daily means; measures of variation reflect differences between individuals). Data are double plotted to ease visualization of the annual pattern. Labels on the x-axis indicate the first month of a two-month interval. Only complete data sets, i.e. those with information about all parameters are plotted. (A) Daily means of heart rate (means ± s.e.m.). (B) Daily means of locomotor activity (means ± s.e.m.). (C) Top: daily means and range of subcutaneous temperature; bottom: daily means of air temperature.