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1. Biological pest control is gaining greater acceptance as an important part of integrated pest management for sustainable agriculture. However, knowledge regarding biological control of rodent pests is limited, and its effectiveness in temperate areas has not been quantified. In traditional Japanese apple orchards, the Ural owl Strix uralensis breeds in tree hollows and preys on the Japanese field vole Microtus montebelli, a native pest species that can harm fruit production. In this study, we hypothesised that the Ural owl, a generalist predator, can act as a biological control agent by reducing vole densities in temperate orchards.2. To quantify the pest control effects of breeding Ural owls, we first analysed the diet of individual owls nesting in apple tree hollows. Second, we installed nest boxes in orchards to attract breeding owl pairs and collected data on vole population changes around owl nests to compare with control areas. The population changes were analysed using a generalised linear mixed model to assess the effect of breeding owls within their breeding territory. The model considered seasonal fluctuations in vole population size as well as surrounding land-use. We also examined vole populations around the owl nests in April, and the distance between nests and forested areas, to determine if these variables influenced nest site selection.3. Voles were the primary prey of Ural owls breeding in orchards and the owls reduced vole populations within their estimated breeding territories by 63% (±SE: 53%-70%) compared with the predicted density without owls. Owls preferred to nest in orchards with higher vole population densities in April. Our findings also indicate that higher occupancy rates are possible by distributing nest boxes based on Ural owl breeding territory size (306 m radius circle in our study). Synthesis and applications.As breeding Ural owls provide significant pest control effects within their breeding territories, the reintroduction of breeding Ural owl pairs within orchards would contribute to rodent pest control. Promoting the reproduction of native raptors in agricultural areas can be an option for developing integrated pest management while simultaneously maintaining regional biodiversity. K E Y W O R D Sbiological pest control, generalist predator, Japanese field vole, microtine population, orchards, predator-prey, rodent pest, Ural owl How to cite this article: Murano C, Kasahara S, Kudo S, et al. Effectiveness of vole control by owls in apple orchards. J Appl

To maintain and recover populations of migratory waders, we must identify the important stopover sites and habitat use along migration routes. However, we have little such information for waders that depend on inland freshwater areas compared with those that depend on coastal areas. Recent technological developments in tracking devices now allow us to define habitat use at a fine scale. In this study, we used GPS loggers to track both spring and autumn migration along the East Asian-Australasian flyway of the little ringed plover (Charadrius dubius) as birds moved to and from their breeding grounds, gravel riverbeds in Japan. The birds we tracked overwintered in the Philippines and made stopovers mainly in Taiwan and the Philippines. The most important habitat during the nonbreeding season was rice paddy fields. Our findings imply that changes in agriculture management policy in the countries along the migration route could critically affect the migration of waders that depend on rice paddy fields. To maintain populations of migrant inland waders that move within the East Asian-Australasian flyway, it is necessary not only to sustain the breeding habitat but also wetlands including the rice paddy fields as foraging habitat for the non-breeding season. Migrant waders have been decreasing on a worldwide scale 1-5 due to various complex reasons 6 , such as land-use change 2 and increasing human activity 4,5. Since these migrant birds use multiple habitats and climatic zones within their annual life cycle 7 , identifying the migration pattern and route, including the habitats used along the way, is imperative for understanding the factors that affect population changes and/or contribute to efficient conservation activities. The loss or degradation of stopover sites is a particularly serious issue 1,2,4-6. In recent decades, therefore, many studies have investigated the migration patterns, detailed migration routes, and important stopover sites for several waders by using tracking methods ranging from traditional color flagging to advanced systems such as satellite and light-level geolocators 8-12. Studies of migration ecology of waders, however, have mainly focused on species that depend on coastal areas (i.e., shorebirds), and there is still little information on those that depend on inland freshwater areas. The low visibility of inland waders compared with that of coastal waders and the coarse spatial resolution of previously used tracking devices (light-level geolocators 13 , 50-200 km; Argos system, <150 m under good conditions and >1000 m under worse conditions 14) made it difficult to determine the fine-scale habitat use of individuals. However, inland natural wetlands have been dramatically declining on a global scale 15 , and some studies in the East Asian-Australasian flyway (EAAF) reported that waders that depend on inland habitat such as rice paddy fields have been decreasing 2,16. For migrant birds, rice paddy fields function much like semi-natural wetlands 17 , and rice is grown across a wide range of la...