Physical Body Parameters of Red-Crowned Cranes Grus japonensis by Sex and Life Stage in Eastern Hokkaido, Japan

Abstract

Red-crowned (or Japanese) cranes Grus japonensis are native to eastern Hokkaido, Japan-the island population, and mainland Asia-the continental population that migrates from breeding grounds along the Amur River Basin to winter in east China and the Korean Peninsula. The island population was reduced to about 50–60 birds in early part of the 20th century. Since 1950s, the population has increased to more than 1,300 as a consequence of human-provided food in winter, resulted in change of their habitats and food resource. From the carcasses of 284 wild cranes from the island population, collected in Hokkaido since 1976 until 2010, we measured six physical parameters (body weight and lengths of body, wing, tarsus, tail and exposed culmen) and divided into groups by sex and three developmental stages (juvenile, yearling and adult). All parameters of males were larger than those of females at the same stage. Total body length of females tends to grow up earlier than males, in contrast to body weight. Obvious time trends were not observed in these all parameters during 34 years for these six categories measured, except total length of male juveniles, which showed a significant increasing trend. These results provide the first extensive data on body size and mass in the wild red-crowned cranes.