Top predators are frequently the target of conservation programs. Owls are such predators. However, previous studies of owls are biased to species occurring in temperate regions, whereas most owl species occur in tropical or subtropical regions and are understudied. Furthermore, owls are often endemic to islands and of unknown conservation status. Demographic data for such species are especially scarce although they are essential for initiating and promoting their conservation. As a case study of demographic analysis of owls in a tropical or subtropical area and on islands, we applied an integrated population model to 7‐year monitoring data (2012–2018) of the Ryukyu Scops Owl population on Minami‐daito Island, Japan. We used survival history data from 903 individuals, reproduction and sex ratio data from 213 broods, and count data of 2,526 individuals in total. Long‐term averages of annual survival rates were 0.73 for adult females and 0.74 for adult males, although the sexual difference was not significant. Sex ratio estimates fluctuated annually and long‐term averages were slightly skewed to males: 0.51 among fledglings, 0.54 among yearlings, and 0.52 among adults. Long‐term averages of population size were estimated to be 273.4 females and 296.8 males. The long‐term average of population growth rate was 0.98, suggesting a slightly declining trend. It was fortunate to recognize the declining trend during the early phase. Considering the general lack of fundamental ecological data on owls of tropical or subtropical areas and on islands, it seems likely that many endangered owl populations await conservation efforts.

The complete mitochondrial genome of Anisakis pegreffii (former A. simplex A) was determined using the Illumina HiSeq platform. The genome was 14,002 bp in length made up of 36 mitochondrial genes (12 CDSs, 22 tRNAs, and 2 rRNAs). Phylogenetic analysis clarified the mitogenome sequences of the three sibling species of the A. simplex species complex, A. pegreffii , A. simplex sensu stricto and A. berlandi (former A. simplex C).

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Parental role division is common among monogamous birds. Among raptors, males typically expend more effort to feed their chicks than do females, yet few studies have focused on how each pair establishes this role division. Therefore, in this study we examined the mechanism of role division in the Ryukyu Scops Owls Otus elegans on Minami-daito Island. Pairs of this species typically remain together and use the same nest over several years, so there is a possibility that their role division improves with experience over time. To clarify this, we studied the feeding frequency and territorial usage of individuals. Males fed their chicks more frequently than females, and experienced individuals using the same nests fed their chicks more than inexperienced individuals. On comparing experienced and inexperienced pairs, we found that experienced individuals hunted closer to the nest than inexperienced individuals. Furthermore, the home ranges of the males and females of experienced pairs, overlapped less than those of inexperienced pairs. Experience of using a nest site in consecutive years may allow such individual behavioural differences to develop and be involved in role division in parental care.