Fig. 1

Correlations between plasma alkaline phosphatase (ALP) and size-corrected mass (SCM) (a wintering: df = 22, t = 2.858, p = 0.009; breeding: df = 23, t = ‒0.281, p = 0.781), and hematocrit (Hct) (b wintering: df = 22, t = 3.036, p = 0.006; breeding: df = 23, t = 0.372, p = 0.713), of male Eurasian Tree Sparrows in the wintering or the breeding stages. Shaded areas are 95% confidence limits