Breeding and renesting of a wild subadult male Red-crowned Crane in Japan

Abstract

There have been no verified breeding records of subadult Red-crowned Crane Grus japonensis in the Japanese population. However, during the 2023 breeding season, a pair, consisting of an adult female and a two-year-old subadult male, was observed in central Hokkaido, successfully hatching one chick. Although both parents displayed chick-rearing behavior, the chick went missing approximately five days after hatching. Later the same season, the pair moved to an adjacent retention basin and attempted to nest a second time, laying and incubating two eggs in June. While these eggs did not hatch, this event provides the first record of both hatching success and renesting, within a single breeding season, by a wild Red-crowned Crane pair involving a subadult individual. This finding highlights the importance of conservation measures for subadult-inclusive crane pairs.