Explanation of the cover photographs
Physical Body Parameters of Red-Crowned Cranes Grus japonensis by Sex and Life Stage in Eastern Hokkaido, Japan
Masako INOUE et al. (pp. 1055–1060)

Developmental stage can be determined by feather pattern and features on the forehead in the red-crowned crane: juveniles (A, D), yearlings (B, E) and adults (C, F). Information on body size and mass by stage and sex is an indicator of population status including changes in their habitats, which can have important implications for their survival.

This number is available on J-STAGE
http://www.jstage.jst.go.jp/browse/jvms/75/8/_contents