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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. 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. 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. Foreign Language 天敵を利用して,農作物を加害する有害生物を抑制する生物的防除手法は,総合的有害生物管理 (IPM; Integrated Pest Management) の主要な柱の一つとして注目を集めつつある.しかしダニや昆虫等を対象にした生物的防除の研究は幅広く行われている一方,同じく主要な加害動物である小型哺乳類の生物的防除の研究は種や地域に限定的で,温帯地域における小型哺乳類の生物的防除の研究は少ない.そこで本研究では,近年まで日本の伝統的なリンゴ園で繁殖していたフクロウStrix uralensisに注目した.フクロウは小型哺乳類の個体数を抑制するとされるジェネラリスト型捕食者である.繁殖期にはリンゴの樹洞に営巣し,害獣であるハタネズミMicrotus montebelliを餌として捕食するが,近年は栽培方法の変化に伴い果樹園内の樹洞が減少し,フクロウの営巣も減少している.本研究では,リンゴ園で繁殖するフクロウがハタネズミの個体数に与える効果を定量的に把握し,フクロウによる生物的防除の可能性を検証することとした. フクロウの効果を定量化するため,まずリンゴの樹洞で繁殖するフクロウが雛に給餌する餌生物を調査した.次にリンゴ園に巣箱を設置してフクロウの繁殖を誘致し,営巣地と営巣地以外のリンゴ園間で,ハタネズミ個体数の季節変化を比較した.個体数解析には一般化線形混合モデルを用い,個体数の基本的な季節変動や周辺の土地利用の影響を考慮したうえで,フクロウの繁殖がハタネズミ個体数に与えた影響を抽出した.またフクロウの営巣場所の選好性を見るため,巣箱周辺の4月のハタネズミ生息密度と,巣箱から森林までの距離を調査し,営巣した巣箱と営巣しなかった巣箱間で比較した. 調査の結果,リンゴ園で繁殖するフクロウが育雛期に巣に運び込んだ餌生物の8割以上がハタネズミであった.またフクロウの繁殖によって,巣周辺のハタネズミ密度は,フクロウの繁殖がなかった場合と比較して63% (± SE: 53%–70%) 減少していた.さらに,フクロウは,4月時点でのハタネズミ生息密度が高い園地を選択的に繁殖に利用していた.また調査期間中の繁殖結果より,フクロウの繁殖期のなわばり面積 (本研究対象地では半径306 mの円) を考慮して巣箱架設を行うことで,巣箱利用率を高められることも示唆された. Synthesis and applications. リンゴ園で繁殖するフクロウは,営巣地周辺のハタネズミ個体数を有意に低減していることが明らかになった.減少しているフクロウの繁殖を巣箱によって再誘致することは,リンゴ園における害獣管理に有効であると考えられる.農地における在来の猛禽類の繁殖支援は,総合的有害生物管理の有効な手段になりうると同時に,地域の生物多様性保全にも貢献できるだろう. 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.

Birds are a frequent host of a large variety of herpesviruses, and infections in them may go unnoticed or may result in fatal disease. In wild breeding populations of owls, there is very limited information about the presence, impact, and potential transmission of herpesvirus. The herpesvirus partial DNA polymerase gene was detected using polymerase chain reaction in oropharyngeal swabs of 16 out of 170 owls examined that were captured in or near nest boxes. Herpesvirus was detected in Ural owls (Strix uralensis), in both adults and young, but not in tawny owls (Strix aluco). In yellow-necked mice (Apodemus flavicollis), as the main prey of tawny owls and Ural owls in the area, herpesvirus was detected in the organs of 2 out of 40 mice captured at the same locations as the owls. Phylogenetic analysis showed that the herpesvirus sequences detected in the Ural owls differed from the herpesvirus sequences detected in the yellow-necked mice. The results indicate that herpesvirus infection exists in the breeding wild Ural owl population. However, herpesvirus-infected owls did not show any clinical or productivity deviances and, based on a phylogenetic comparison of detected herpesvirus sequences and sequences obtained from Genbank database, it seems that mice and other rodents are not the source of owl infections. The most probable transmission pathway is intraspecific, especially from adults to their chicks, but the origin of herpesvirus in owls remains to be investigated.

Apex predators, such as raptors, are used as surrogates to attain conservation objectives; however, their presence in a particular area does not necessarily mean long-term occurrence. Here we used data on long-lasting (20–40 years) territories of two generalist raptors: the diurnal Northern goshawk and the nocturnal Ural owl in deciduous and coniferous forests of southern Poland to assess their role as hotspots of bird diversity. Species richness and abundance of birds were much higher in the long-lasting territories of both apex predators than in random never-occupied sites and this pattern was common for breeding and wintering periods. These differences were more pronounced in deciduous than coniferous stands. Rare bird species (e.g., annexed in the Bird Directive of the European Parliament and of the Council on the conservation of wild birds such as some woodpeckers and flycatchers) were found to be particularly associated with long-lasting territories of raptors. Long-lasting territories were also characterized by greater forest habitat quality (e.g., higher number of old trees and deadwood) with lower management intensity. These results strongly point to the role of long-lasting territories of raptors as surrogates of biodiversity. Such territories, if known in forests, could be excellent for the designation of protected areas or logging there should at least be reduced to allow for the continuous breeding of apex predators and associated bird assemblages.

While much effort has been made to quantify how landscape composition influences the distribution of species, the possibility that geographical differences in species interactions might affect species distributions has received less attention. Investigating a predator-prey setting in a boreal forest ecosystem, we empirically show that large-scale differences in the predator community structure and small-scale competitive exclusion among predators affect the local distribution of a threatened forest specialist more than does landscape composition. Consequently, even though the landscape parameters affecting Siberian flying squirrel ( Pteromys volans ) distribution (prey) did not differ between nest sites of the predators Northern Goshawks ( Accipiter gentilis ) and Ural Owls ( Strix uralensis ) , flying squirrels were heterospecifically attracted by goshawks in a region where both predator species were present. No such effect was found in another region where Ural Owls were absent. These results provide evidence that differences in species interactions over large spatial scales may be a major force influencing the distribution and abundance patterns of species. On the basis of these findings, we suspect that subtle species interactions might be a central reason why landscape models constructed to predict species distributions often fail when applied to wider geographical scales.

Some moth larvae feed not on plants but on keratin and/or chitin produced by animals. These substances are polymers and are commonly found in bird nests as feathers and raptor pellets. Many qualitative studies have examined the association of keratin/chitin feeding moths with bird nests. However, few studies have quantifl ed the species composition with respect to type of nest and habitat. Hence, we have studied the degree to which the niches of these moths differ in terms of type of nest and habitat. We set-up open-top nest boxes for the Ural owl Strix uralensis (damp exposed nests from which owl chicks were fl edged successfully) and artifi cial bird nests (mesh bags fl lled with duck down to imitate dry exposed nests) in a deciduous forest and artifi cial bird nests in an urban setting in Aichi Prefecture, central Japan, and collected the contents of the nests every two months from June to December 2014. We recorded 592 individuals of fl ve keratin/chitin feeding moth species (Tineidae, Tineinae) from the contents. Using non-metric multidimensional scaling and cluster analysis of the relative abundances of individual species in each type of nest in forest and urban settings, these species were classifi ed into three groups: (1) Monopis longella and M. congestella inhabiting forest, (2) M. flavidorsalis and Niditinea tugurialis mainly in damp exposed nests in forest and (3) N. piercella mainly in dry exposed nests in urban areas. This classifi cation was compared with fl ndings of other studies. As a result, these moths probably have different niches with respect to nest type (damp or dry), keratin/chitin as a source of food (raptor pellets or feathers), and habitat (forest or urban area). Furthermore, we suggest that the evolution of larviparity in M. congestella might be related to its preference for feathers as a source of food for the development of its larvae.

The results of the study of the Ural Owl feeding spectrum are presented. In Russia the Ural owl eats over twenty species of mammals, thirty bird species and a number of animals of other classes. The research tasks included the identification of the species of the victims of a large owl in Mordovia, their quantitative data and the characteristics of osteological material from pellets. It was found out that mammals, in particular rodents, are the basis for the Ural owl food. The Ural Owl’s diet consists mainly of gray voles (47.7 %). On the second place there is a red vole (31.4 %). The share of mice is only 7.3 %. Th e predator hunts for the forest mouse most oft en. In pellets the mass fraction of bone remains varies in the range from 3.4 to 44.8 %. Th e average proportion of bone remains is, as a rule, up to 25 %, with the content of only one or two small rodents in pellets; the remains of three to six individuals - up to 45 % of the weight of dry pellet. Among all the bones of mammals, the lower jaws, femoral and tibia bones give the greatest information about the number and composition of victims of the Ural owl. In pellets the brachial and nameless bones of the victims are presented in smaller numbers.

Life-history components may be food-limited. We supplemented food to 18 Ural owl, Strix uralensis, nests during the nestling period. Food supplementation led to a higher somatic condition in the female parent, but effects in males were moderate. Parents delivered less food to fed nests than to control nests. Offspring survival and fledging condition did not differ between control and fed nests. In the season following food supplementation, fed pairs bred 1 week earlier than control pairs and, coupled to this advance in laying date, fed pairs produced 0.6 eggs more than control pairs. This is the first evidence that food limitation in the current season may constrain next season's reproduction. Such carry-over effects of food-limitation may have important consequences for population dynamics.

We examined the effects of predatory and competitive interactions among three owl species on reproductive success and population composition of these raptors both experimentally and observationally. Eagle Owls (Bubo bubo, body mas $\\approx$ 2700 g), Ural Owls (Strix uralensis, 900 g), and Tengmalm's Owls (Aegolius funereus, 130 g) coexist in Fennoscandia and feed mainly on small rodents. Predation may play an important role in interactions among these owl species, because Eagle Owls and Ural Owls can kill Tengmalm's Owls but cannot enter the small entrance hole of Tengmalm's Owl nest boxes. We asked (i) whether predation risk and interspecific competition due to Eagle Owls and Ural Owls reduced breeding density and fitness of Tengmalm's Owls, and (ii) whether these interactions increased intraspecific competition for safe nesting sites among Tengmalm's Owls. We manipulated breeding densities of potentially competing owls by erecting nest boxes, the control being boxes in areas where breeding attempts of competing owl species were absent. Control nest boxes in areas with no Eagle Owl and Ural Owl territories, and nest boxes within Eagle Owl territories, were used by breeding Tengmalm's Owls more than nest boxes within Ural Owl territories. Most breeding attempts of Tengmalm's Owls near Ural Owls failed during the courtsip period. The observational data revealed that breeding frequency of Tengmalm's Owls was reduced and the mean start of egg laying was delayed by 11 d within 2 km of Ural Owl nest. In addition, male Tengmalm's Owl at these nests were younger and paired more often with short—winged (i.e., young and generally subdominant) females than when farther away from Ura Owl nests. Our results suggest that inexperienced male Tengmalm's Owls are forced to establish their territories in the vicinity of Ura Owls where they often paired with subdominant females. The areas near Ura Owl nests are suboptimal habitats for Tengmalm's Owls, whereas those near Eagle Owls are not. We conclude that predatory and competitive interactions from Ural Owls decrease the breeding population size of Tengmalm's Owls by reducing the suitable habitats. This is the first experimental demonstration that such interactions may decrease fitness of raptors.

1. Individuals are expected to balance the costs and benefits underlying the trade-off between current and future reproduction. If starting to breed does not seriously lower future reproductive output, individuals that start breeding early in their life should have a higher fitness than individuals that postpone their breeding career. We studied how the fluctuations in food supply interacted with Ural owl's age at first breeding, lifetime reproductive success (LRS) and fitness. 2. During the period 1977-95, 126 Ural owl females started and ended their breeding career in a study area in southern Finland. Voles, the owls' main food source, showed a 3-year cycle of low, increase and peak population numbers. We recorded when the females started to breed and how many fledglings they produced. For 57 females the age at first breeding was known. 3. LRS of female Ural owls varied from 0 to 33 fledglings (mean 6.7 ± 0.52 SE). The variance in LRS was explained by variation in the components: breeding lifespan (97%); nest success (23%); and average clutch size (15%). 4. Survival of breeding females was low (62%) after a peak year, when the vole population crashed. In other phases the survival was 85-95%. Females that started breeding in a peak year had half the LRS of females that started in an increase year. 5. There was a strong interaction between the vole cycle and age at first breeding. 1-year-olds started in a peak and 2-year-olds in an increase year. 6. There was no effect of age at first breeding on LRS for females that started breeding in the same phase of the vole cycle. 7. Females that started breeding at age 1-3 years had equal fitness, whereas females that started at age ⩾ 4 had a lower fitness. Females that postponed first breeding as a two-year-old in an increase year had a lower fitness than females that did not do so. Females that postponed first breeding as a 1-year-old in a peak year had equal fitness to females that did not do so. 8. Cyclic fluctuation in food supply clearly constrains the option as to during what phase and at what age to start breeding. In terms of fitness, the optimal age to start breeding depends on the phase of the vole cycle at hatching.

Life‐history theory concerns the optimal spread of reproduction over an organism’s life span. In variable environments, there may be extrinsic differences between breeding periods within an organism’s life, affecting both offspring and parent and giving rise to intergenerational trade‐offs. Such trade‐offs are often discussed in terms of reproductive value for parent and offspring. Here, we consider parental life‐history optimization in response to varying offspring values of a population regulated by territoriality, where the quality of the environment varies periodically. Periods are interpreted as either within‐year (seasonality) or between‐years variation (cyclicity). The evolutionarily stable strategy in a general model with two‐phased periodicity in the environment can generate either higher or lower effort in the more favorable of the two phases; hence knowing survival prospects of offspring does not suffice for predicting reproductive effort—the future of all descendants and the parent must be tracked. We also apply our method to data on the Ural owlStrix uralensis, a species preying on cyclically fluctuating voles. The observed dynamics are best predicted by assuming delayed reproductive costs and Type II functional response. Accounting for varying offspring values can lead to cases where both reproductive effort and recruitment of offspring are higher in the phase when voles are not maximally abundant, a pattern supported by our data.