Cooperative den maintenance between male Japanese badgers that are delayed dispersers and their mothers

In some vertebrates, sexually mature individuals delay dispersal from their natal sites. Delayed dispersers are known to help their parents in many species; however, few studies have investigated the behavior of delayed dispersers in carnivores. Male offspring of the Japanese badger, Meles anakuma, remain in their natal sites and share setts with their mothers well after reaching sexual maturation. In this study, we investigated the contribution of male delayed dispersers in den maintenance activities of digging and bedding at their setts from September to February between 2010 and 2018. We found that delayed dispersers contributed approximately 60 and 30% of digging and bedding tasks, respectively. Specifically, while digging was constantly performed throughout the surveyed period, efforts in bedding gradually increased from September to February. We also found that delayed dispersers occasionally performed digging and bedding simultaneously with their mothers and siblings. Mothers may allow the male offspring to remain in the natal sites because of their help with den maintenance. It is probably advantageous for the males to remain in a familiar environment and have access to resources until they become large and competitive enough to establish and defend their mates and their own territories. Digital video images related to the article are available at http://www.momo-p.com/showdetail-e.php?movieid=momo210707ma01a, http://www.momo-p. com/showdetail-e.php?movieid=momo210707ma02a, http://www.momo-p.com/showdetail-e.php?movieid=momo210707 ma03a, http://www.momo-p.com/showdetail-e.php?movieid=momo210707ma04a, http://www.momo-p.com/showdetail-e. php?movieid=momo210707 ma05a, http://www.momo-p.com/showdetail-e.php?movieid=momo210707ma06a and http:// www.momo-p.com/showdetail-e.php?movieid=momo210707ma07a..