Figure 1.
Reaction norms according to three scenarios.
In (a) individuals express different elevations and slopes, in (b) individuals express different elevations but similar slopes and in (c) individuals express the same elevations and slopes, which reflect the population reaction norm.
Table 1.
Sample sizes presented relative to the number of capture per bird.
Figure 2.
Relationship between mass and sex independent BMR and the natural range of minimal ambient temperature.
Residual BMR were extracted from an ANCOVA controlling for body mass and sex. Population-average reaction norm is represented by the black line while grey lines represent reaction norms of individuals caught more than five times.
Figure 3.
Mass and sex independent Msum variation over the natural range of weather conditions.
Data are residual Msum presented against (a) minimal ambient temperature (min Ta) and (b) residual minimal absolute humidity. Black dots in (b) represent data collected at min Ta<0°C, white dots at 0°C<min Ta<16°C and grey dots at min Ta>16°C (see text for details). For both panels, black lines are curves fitted by loess (smoothness = 0.85, degree = 2). Residual Msum were extracted from ANCOVA controlling for body mass, sex as well as residual minimal absolute humidity in (a) or minimal temperature in (b). Residual minimal absolute humidity controls for the effect of ambient temperature and was extracted from a polynomial regression. Coefficients of determination are presented for independent relationships, see text for complete model.
Table 2.
Best model explaining mass and sex independent Msum variations.
Figure 4.
Monthly variations in minimal temperature.
Data are extreme low, mean and extreme high values per month for minimal ambient temperature.