Near threatened? First report of unsuspected human-driven decline factors in the Ryukyu flying fox (Pteropus dasymallus) in Japan

Abstract

Japan hosts the largest population of the threatened Ryukyu flying fox (Pteropus dasymallus), which, in Taiwan, suffered a drastic decline leading to local extinctions and, in the Philippines, remains only on three small islands. Conservation of the species in Japan is therefore crucial. National and international assessments have been based only on local anthropogenic factors, such as habitat degradation, electrocution on power lines, and accidental entanglements.Using face-to-face interviews of farmers of the Yaeyama islands (southwestern part of the Ryukyu archipelago), we discovered that other significant human-driven causes of decline were overlooked in assessments. Most importantly, we report here for the first time on the illegal killing of this species by farmers because it feeds on crops. The bat has been killed by intense poisoning, beating, and netting. Other cases of illegal infringement of animal welfare principles by the general population were also encountered (i.e. confinement and mistreatment) but could not be quantified. Furthermore, we also determined the historical use of flying fox meat as a food source, which has also never been documented before. Finally, we identified emerging threats that were previously neglected in the assessments of the species' conservation status, namely predation by feral or semi-feral cats and dogs, whose populations have been booming in recent years. These unexpected factors, especially the ongoing killing of P.d. yayeyamae, call into question the IUCN downlisting (EN→NT) decided in 2008, when poisoning campaigns were actually culminating, and lead us to recommend the initiation of conservation actions (particularly population monitoring), education campaigns, as well as the provision of technical assistance to farmers in need of it.