Age of first primary moult in the Red-crowned Crane Grus japonensis

Abstract

The Red-crowned Crane Grus japonensis population of Hokkaido, Japan, has increased to over 1,600 individuals since near extinction in the late 19th and early 20th centuries. Adults and subadults can be distinguished by visible characteristics of their remiges; adults have pure white primaries whereas subadult birds have black primary tips and upper primary wing coverts. Banded individuals hatched during 2015–2017 were examined in detail using photographs and videos and it was found that the subadult characteristics of the remiges disappeared in individuals older than two years.