No abstract

Reforestation, which converts abandoned farmland back into forestland by planting woody species, can provide habitat for wildlife, including the brown bear (Ursus arctos Linnaeus, 1758). In the Shiretoko World Heritage site, northern Japan, where brown bears occur at high density, conifers have been planted since the 1970s to reforest abandoned farmland. In this area, brown bears were first observed digging for cicada nymphs (Lyristes bihamatus Motschulsky, 1861) from 2000. Our preliminary observations suggested the emergence of digging behavior might be associated with reforestation. We examined whether reforestation provided a foraging habitat for brown bears. We found that digging occurred only within the restored conifer forests, but not within the natural forest. The densities of cicada nymphs in the restored forests were higher than in the natural forest. These results indicate that the reforestation of abandoned farmland provides a foraging habitat for brown bears by increasing the availability of cicada nymphs in the Shiretoko World Heritage site.

No abstract

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Cicadas, a group of large-bodied insects, are preyed upon at both nymphal and adult stages by diverse range of vertebrates such as birds and mammals. Although the behavior of predators toward adult cicadas is well documented, there is a lack of research on the predation on cicada nymphs. In this study, camera-traps deployed in conifer plantations, in which high population densities of cicadas Lyristes bihamatus emerge, were used to evaluate the seasonal and diel patterns of predation upon cicada nymphs by three predator species, namely brown bears, red foxes, and jungle crows from May to September in 2018 and 2019 in northern Japan. Among all three species, cicada nymph predation occurred until early August when the final instar nymphs fully emerged. Bears were observed to constantly dig for cicada nymphs until early August, whereas foxes and crows were frequently observed foraging from late July to early August, during the season of L. bihamatus emergence. In contract to the powerful digging ability of bears, which facilitates efficient predation upon subterranean cicada nymphs, it is generally difficult for foxes and crows with limited or no digging ability to gain access these nymphs until the period of emergence. Cicada nymph predation by bears and crows was observed primarily during the daytime, despite the typical crepuscular/nocturnal emergence schedules of these insects. Contrastingly, the predatory activities of foxes tended to be nocturnal during the period prior to the beginning of cicada emergence, although subsequently became diurnal during the cicada emergence period. These observations indicate that the temporal activity patterns of cicada nymph predators are determined by interspecific differences in predation abilities and cicada emergence schedules. Accordingly, the findings of this study provide evidence to indicate that the timing and duration of trophic interactions between above-and belowground communities might vary among predator species, depending on their predation abilities.