Lepidoptera fauna of five owl species nests were investigated in Japan. Seventeen moth species were identified: Niditinea striolella (Tineidae), Agonopterix sp. (Elachistidae) from Blakiston's Fish Owl, Ketupa blakistoni, nests; Monopis longella (= pavlovskii), M. flavidorsalis, M. sp., M. congestella, Niditinea baryspilas, N. striolella, N. sp. (Tineidae), Martyringa ussuriella (Oecophoridae), Mabra charonialis (Crambidae), Pyralis regalis (Pyralidae) from Ural Owl, Strix uralensis, nests; Tinea translucens, Niditinea baryspilas (Tineidae) from Brown Hawk-Owl, Ninox scutulata, nests; Opogona sacchari, O. sp., Phaeoses sp. (Tineidae) from Collared Scops Owl, Otus lempiji, nests; and Opogona sacchari, Phaeoses sp., Setomorpha sp. (Tineidae), Endotricha theonalis (Pyralidae) from Ryukyu Scops Owl, Otus elegans, nests. The moth nest fauna varied among owl species. The differences were related to owl prey (fish, small animals and birds, insects) and habitats (urban area, forest), and the tineid species selecting the nest. Tineids are presumed to decompose keratin found in owl nests and help maintain the cleanliness of the nest chamber, and such relationships between tineids and owls may be mutualistic. Rapid burrowing into owl nest materials by tineids may reflect a strategy to avoid being preyed upon by the nest owners.

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Although Narcissus Flycatchers readily use nest boxes, natural nest sites and nest characteristics have not previously been described. The location of 41 Narcissus Flycatcher nests and data on the dimensions of 17 nest holes in the Fuji Primitive Forest of Japan are described. Japanese Hemlocks were the most commonly chosen tree species for nesting although 14 other tree species were also used and no significant nest tree species preference was observed. Nests (classified as either half cavity, full cavity, chimney, or shelf), were built at an average height of 7.3 m. Flycatchers tended to nest in dead trees or trees with trunks greater than 20 cm in diameter (mean 30.9 cm). Nests were typically made from dead leaves, moss, plant fibers, and animal hair. This is the first description of natural nest sites and nest characteristics of Narcissus Flycatchers; details are compared with those of other closely related flycatcher species.

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To evaluate the relative importance of rice fields for Grey Herons Ardea cinerea, habitat use by the herons in rural areas, including farmlands, streams, ponds, and lakes, was investigated in Ishikari district, western Hokkaido. To clarify habitat use by herons, censuses along 81 km long routes in rural areas and point counts at four sites (ponds and lakes) were conducted. Grey Herons used rice fields from mid June to mid August, but did not use this habitat either in April or after late September. Some herons used pond, lake, and river habitats in early April, but the number of herons in these habitats decreased from early June onwards and increased again from mid August until mid September. Heron numbers declined in late September, with few herons using ponds, lakes, and rivers until mid November. Herons used natural wetland habitats in spring, but when rice fields were flooded, they switched to this habitat. When water was drained from rice fields in late August, herons returned to natural wetlands. Observations revealed that herons feed mainly on tadpoles in rice fields and on small fish in ponds and lakes. Foraging success was higher, and time to capture one prey item was shorter, in rice fields compared with that in lakes and ponds. Intensive use of rice fields by Grey Herons coincided with the occurrence of Japanese Tree Frog Hyla japonica tadpoles in this habitat type. Grey Herons therefore use rice fields to feed on tadpoles. This suggests that tadpoles are important prey item for Grey Herons in this region.

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Willow Tits Poecile montanus produce calls when they discover food sources. These calls function to attract conspecific and heterospecific individuals to the food site, thereby facilitating the formation of mixed-species foraging flocks. Since individuals may gain feeding/anti-predator benefits while foraging in mixed-species flocks, the ability of food discoverers to signal food presence would be of adaptive value. Here, I tested this idea by comparing the calls of Willow Tits between food and non-food contexts. Field observations at artificial feeders showed that Willow Tits typically produce calls composed of a single note type (tää note) when discovering food supplies, whereas they usually combine two distinct note types (introductory and tää notes) when moving through forests without a food source. These results indicate that Willow Tits use subtle variation in the note composition of calls to discriminate between food and non-food contexts, and this may serve to regulate the movements and cohesion of mixed-species flocks.

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The distributions of the Little Cuculus poliocephalus and Oriental C. saturatus cuckoos differ throughout Japan. In Honshu, the Little Cuckoo parasitizes mainly the Japanese Bush Warbler Cettia diphone and lays reddish mimetic eggs. The Oriental Cuckoo mainly parasitizes the Eastern Crowned Leaf Warbler Phylloscopus coronatus and lays whitish eggs. However, in central Hokkaido, where no Little Cuckoos breed, Oriental Cuckoos parasitize Japanese Bush Warblers as their main hosts, in whose nests they lay reddish eggs. Anecdotal evidence suggests that they also parasitize Eastern Crowned Leaf Warblers, laying reddish eggs, but this has not been confirmed. Here, we report the first complete evidence in which an Oriental Cuckoo chick, which hatched from a non-mimetic reddish egg, was raised by Eastern Crowned Leaf Warbler hosts in Hokkaido.

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Carbon and nitrogen stable-isotope ratios were measured in the egg yolks of four species of seabirds in Teuri Island and Rishiri Island, Japan. Delta ¹⁵N of the yolks of Rhinoceros Auklets Cerorhinca monocerata (11.2–12.3‰) and Black-tailed Gulls Larus crassirostris (11.3–12.5‰) were lower than those of Slaty-backed Gulls Larus schistisagus (13.4–14.2‰) and Japanese Cormorants Phalacrocorax capillatus (14.0–16.2‰); suggesting that the former two species foraged mainly on low trophic level small fishes and sometimes on krill, while the latter two species fed on higher trophic level prey and larger fishes.

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The behavior of frugivorous birds during the removal of fruit from Swida controversa was investigated to compare the relationships between measures of fruit maturation and quantitative fruit removal behavior of birds. Bird exclusion devices were used on some branches to allow comparison of the traits of removed and un-removed fruits. Nine bird species visited S. controversa, but only four removed fruit, and each bird species removed a different number of fruits per visit. Only 11.5% of a branch's fruits were removed by birds. Birds removed only larger, blacker, more mature fruits, suggesting birds were effective seed dispersers.

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