Fig. 3. Allometry of the surface area of the blood–gas tissue barrier (S_t) of 12 Australian pelicans during post-hatching growth (filled circles), excluding one adult bird (open circle). Data from 26 species of adult birds (triangles) are from Maina et al. (1989). Regression equations: pelicans S_t=1.41M^1.25 (r²=0.97); adult birds S_t=60.2M^0.86 (r²=0.94).