Figure 3. Variation in offspring signals across species.

Circles represent species' mean z-transformed correlation coefficient between condition and (a) begging intensity (N=56 species) and (b) structural signal intensity (N=18 species). The grand mean and 95% credible interval (CI) are denoted by the shaded bar. Blue, solid lines indicate that chicks that in worse condition signal more. Black, solid lines indicate that chicks in better condition signal more. Red, dashed lines indicate no effect of condition on signals. Lines show 95% CI (±s.e. × t_critical). s.e. was estimated from the pooled number of broods across all studies.