Ornithological Science
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EDITORIAL
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ORIGINAL ARTICLE
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White Crow: 18-Nucleotide Deletion Leading to the Absence of Six Amino Acids
View Description Hide DescriptionAbstractTwo Carrion Crow Corvus corone kept at a bird conservation facility in Niigata, Japan, had entirely white plumage, pink feet and beaks, and red eyes, indicative of a lack of melanin pigments. Tyrosinase, an enzyme essential for melanin biosynthesis, is encoded by the TYR gene. Sequencing analysis of TYR of the white individuals revealed a deletion of 18 consecutive nucleotides, leading to the loss of six amino acids from the tyrosinase protein. The body color mutation is likely to have been caused by this 18-nucleotide deletion. White crows have been found frequently in the Niigata region for over 30 years. The deletion mutant gene is considered to persist in the natural Carrion Crow population of this region, mainly in heterozygous carriers and primarily owing to random genetic drift.
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SHORT COMMUNICATION
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Observations on the Breeding Ecology of Lesser Kestrel Falco naumanni (Fleischer 1818) at a New Breeding Site in Southeastern Türkiye
View Description Hide DescriptionAbstractA new breeding site for Lesser Kestrel was identified and the nesting area was monitored between 2019–2022 at Diyarbakır, Türkiye. Birds arrive at the nesting site at the end of March and breeding commences with courtship behaviour and copulation at the beginning of April. Incubation starts in mid April and lasts until mid-May when the eggs hatch. The juveniles fledge at the end of June, and begin to practice hunting with adults in early July. Further monitoring of the population is recommended.
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Effects of Artificial and Natural Substrates on Breeding Birds in a Japanese City
View Description Hide DescriptionAbstractPrevious studies on urban bird diversity have paid attention to green spaces. However, non-green spaces in urban areas may also be important for bird species nesting in artificial structures. We established a study area in Hakodate City, Hokkaido, Japan, and searched for all nests of birds breeding in the area. We found that 15% (N=22) of these nests were built on natural substrates and 85% (N=129) on artificial substrates. Of the 14 species recorded nesting, eight species nested only in natural substrates and four species nested only in artificial substrates.
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ORIGINAL ARTICLE
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Expansion of the Range of the Light-Vented Bulbul Pycnonotus sinensis into Mainland Japan
View Description Hide DescriptionAbstractThe distribution of Light-vented Bulbul Pycnonotus sinensis has been expanding in East Asia in recent decades. Since the 2000s it has even bred sporadically in mainland Japan, in both Kyushu and Honshu, which it may have reached by natural dispersal. In this study, we aimed to clarify the origins of the birds seemingly colonising western Japan. First, we reviewed observations of the species in South Korea and western Japan and clarified spatiotemporal changes in its distribution since the 2000s. Second, we captured Light-vented Bulbul in Kitakyushu, where it has been observed since 2017 and compared its morphological characteristics and ND2 sequence in the mitochondrial DNA with those of other populations. We obtained three key results: 1) the number of observations of the Light-vented Bulbul has increased since the late 2000s in western Japan, which is consistent with the timing of its expansion in South Korea; 2) individuals captured in Kitakyushu had morphological characteristics similar to those of P. s. sinensis in China; and 3) we observed multiple haplotypes in the Kitakyushu population, which were all included in the cluster of P. s. sinensis and P. s. hainanus, but not included in the cluster of P. s. formosae in Taiwan, P. s. orii in the Yaeyama Islands, or in the unidentified subspecies on Okinawajima Island. These results suggest that China is the origin of individuals recently observed in western Japan, and it is considered likely that dispersal has occurred naturally from the Eurasian continent via the Korean Peninsula. Since the Light-vented Bulbul has already become established, and is still increasing in numbers, in southeastern South Korea, observations are also likely to increase in western Japan.
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SHORT COMMUNICATION
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Effects of Plant and Avian Frugivore Interaction Networks on Landscape Patterns and Seed Dispersal Functions in the Southern Western Ghats, India
View Description Hide DescriptionAbstractThe Western Ghats is a global hotspot of biodiversity. In this descriptive study at the foothills of the Western Ghats, our aim was to further our understanding of the complex interaction between frugivorous birds and trees. The bird numbers were assessed using the distance line transect method and the fruit preferences of birds were recorded using a 4K video camera. A strong positive correlation was found between the number of plant species and the abundance of bird species in each study area, which emphasizes the importance of avian seed dispersers in an ecosystem, and the essential value of studies of frugivory to devise conservation measures for frugivores and frugivore dispersed plants.
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Topography of Retinal Ganglion Cells of a Northern Goshawk Accipiter gentilis
View Description Hide DescriptionAbstractThe retina of a Northern Goshawk Accipiter gentilis was investigated in a whole-mount preparation using Nissl's staining method. The total number of retinal ganglion cells (RGCs) was 4,427.2×103. The visual streak extended horizontally across the retina with an RGC density of 10.3–22.8×103 cells/mm2. This area included two foveal areas in central and temporal locations with densities of 22.8×103 and 22.7×103 cells/mm2, respectively. The localization of RGCs larger than 10 µm in diameter was observed in the periphery of the dorsal, nasal, and temporal retina. These results may reflect adaptation of the goshawk's eye to its ecological environment and behavior.
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ORIGINAL ARTICLE
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Absence of Genetic Structure among Streaked Shearwaters Calonectris leucomelas Breeding in Japan, Despite Limited Dispersal Events
View Description Hide DescriptionAbstractThe genetic structure of Streaked Shearwater Calonectris leucomelas, a seabird breeding on islands around Japan, was investigated using nuclear microsatellite markers at four breeding colonies located in three geographically distinct areas (Pacific Ocean, Sea of Japan, and Seto Inland Sea). To investigate independently natal and breeding dispersal patterns, we analyzed records of recoveries of birds banded around Japan over a 30-year period from 1971 to 2020. The genetic marker analysis showed little differentiation among the breeding sites and a lack of population structure. In contrast, banding data presented few examples of natal and breeding dispersal and a much greater number of natal/breeding philopatry cases. Although further research is needed to understand the discrepancy between the genetic properties and recapture patterns of banded birds, some possible reasons are suggested: actual dispersal events may not have been fully detected by the banding research, thus, underestimating dispersal frequency; rare dispersal events may have functioned to reduce the genetic structure; and/or breeding colonies of this species might have been established recently, thus genetic markers may not be indicative of current dispersal patterns. In conclusion, our results indicate ongoing gene flow and/or strong historical association in this species.
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Eastern Buzzard Buteo japonicus toyoshimai Breeding on the Ogasawara Islands Depend on Non-Native Rats as a Food Source
View Description Hide DescriptionAbstractSince human settlement of the Ogasawara Islands in the early 19th century, several bird species have become extinct owing to the impact of the introduction of non-native species, and other factors. In particular, on the island of Hahajima, seabird breeding colonies have been devastated. This study aimed to determine the relationship between the endemic subspecies of Eastern Buzzard Buteo japonicus toyoshimai and various non-native rats on Hahajima, Ogasawara Islands, Japan. Over a period of 5–10 years video-recordings were made of food being delivered to buzzard nests at three study sites on Hahajima. Rats Rattus spp. were the most abundant prey delivered to the nestlings, accounting for 71–91% of prey items and 83–96% of prey weight; next in abundance was the introduced Green Anole Anolis carolinensis, 6–21% in number. However, since anoles are much smaller than rats, even at the study site where a high proportion of anoles were delivered, the buzzard pair there did not consume fewer rats than at the other sites. Only a small number of birds (1–6%) were delivered to the nests. At one site, where breeding occurred seven times during the study period, there was a significant positive correlation between the number of rats delivered to the nest during the nestling period and precipitation in the October before breeding and in January of the year of breeding.
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Fine-Scale Nuclear Genetic Structuring within the Ryukyu Robin, a Species Complex Endemic to the Ryukyu Archipelago
View Description Hide DescriptionAbstractThe Ryukyu Robin species complex, including the Ryukyu Robin Larvivora komadori and the Okinawa Robin L. namiyei, is endemic to the islands of the Ryukyu Archipelago. Population genetic structure and gene flow within this complex were investigated using 14 nuclear microsatellite markers. Distinct genetic differentiation was detected between the Ryukyu and Okinawa robins, and the Ryukyu Robin was further differentiated into four regional groups belonging to the Danjo Islands, Tokara Islands, Oh-shima with some adjacent islands, and Tokuno-shima. Contemporary gene flow among these regional groups was restricted overall, but outflow from the Tokara Islands group to the other three groups was exceptionally high. This asymmetric pattern may have been affected by differences in the isolation distance, migratory habits, and population size. The Ryukyu Robin species complex was long considered a single polytypic species; however, it has recently been classified as two independent species, mainly owing to the deep mitochondrial DNA divergence between them and a phenotypical re-examination. The genetic structure inferred from the nuclear loci strongly supports their genetic independence. The Okinawa Robin provides the first case among birds for which the splitting of sister species both endemic to the Ryukyu Archipelago is supported by all of the morphological, behavioral, ecological, and genetic evidence. Such recognition appears preferable in avian conservation and biogeography studies. Currently, the Ryukyu Archipelago includes an Endemic Bird Area and two Natural World Heritage sites, making the reliable delimitation of endemic species all the more important. Comprehensive genetic investigation, together with phenotypical re-examination is necessary, even for closely resembling but allopatric sister forms in this region.
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