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Last Updated :2024/08/24

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Master

Affiliation (Master)

  • Faculty of Science　Biological Sciences　Biodiversity

Affiliation (Master)

  • Faculty of Science　Biological Sciences　Biodiversity

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Profile and Settings

Affiliation

  • Hokkaido University, Faculty of Science
  • Yamashina Institute for Ornithology

Degree

  • Doctor of Agriculture（1997/03 Hokkaido University）

Profile and Settings

  • Name (Japanese)

    Takagi

  • Name (Kana)

    Masaoki

  • Name

    200901042533999070

Affiliation

  • Hokkaido University, Faculty of Science
  • Yamashina Institute for Ornithology

Achievement

Research Interests

  • 保全生態学   Bioacoustics   Biogeography   Avian Ecology   Island Biology   Ornithology   Animal Ecology   

Research Areas

  • Life sciences / Evolutionary biology
  • Life sciences / Biodiversity and systematics
  • Environmental science/Agricultural science / Biological resource conservation
  • Life sciences / Ecology and environmental science

Education

  •        - 1997/03  Hokkaido University

Awards

  • 2021/12 日本生態学会北海道地区会 奨励賞
     果樹園で繁殖する絶滅に瀕する渡り⿃の個体数減少に⽣活史戦略が与える影響 
    受賞者: ⾚松あかり, ⻘⽊⼤輔, 松宮裕秋, 原星⼀, 古巻翔平, 髙⽊昌興
  • 2021/03 第68回日本生態学会 ポスター賞最優秀（行動）
     体サイズに関する同類交配は積極的な配偶者選びの結果か：長期研究データによる検証 
    受賞者: 澤田 明;岩崎 哲也;高木 昌興
  • 2019/10 日本鳥学会 ポスター賞
     餌資源の豊富ななわばりで冬を越せた個体は、その後の繁殖が上手くいくのか？ 
    受賞者: 西田有佑;高木昌興
  • 2019/09 個体群生態学会 ポスター賞優秀賞
     分散距離の性差が先か？近親交配の回避が先か？ 
    受賞者: 澤田明;小野遥;高木昌興
  • 2019/03 石狩川流域湿地・水辺・海岸ネットワーク 第3回フォーラム学生ポスター最優秀賞
     オシドリ奥様のご近所づきあい 種内托卵に根差した生活史研究 
    受賞者: 坂本春菜;青木大輔;新田啓子;高木昌興
  • 2019/03 日本生態学会 ポスター賞優秀賞
     感覚便乗による鳥の声の地理的変異は交配前隔離の機構としてはたらく 
    受賞者: 植村慎吾;高木昌興
  • 2019/03 日本生態学会 英語口頭発表Best Award
     Light-level geolocators and phylogeography reveal the evolutionary uniqueness of the Japanese-endemic migratory bird subspecies 
    受賞者: Daisuke AOKI・Haruna SAKAMOTO・Hiroaki MATSUMIYA・Munehiro KITAZAWA;Masaoki TAKAGI
  • 2018/10 個体群生態学会 ポスター賞優秀賞
     Genetic data of an extinct population can offer insights into processes that a natural population successfully colonize a previously uninhabited area 
    受賞者: Daisuke AOKI;Shin MATSUI;Junko NAGATA;Mariko SENDA;Fumiaki NOMANO;Masaoki Takagi
  • 2018/09 日本鳥学会 ポスター賞
     絶滅した自然集団DNA から生物が新しい集団形成を可能にする条件を探る 
    受賞者: 青木大輔;松井晋;永田純子;千田万里子;野間野史明;髙木昌興
  • 2018/03 日本生態学会 ポスター賞最優秀賞
     オスの貯食行動は性選択によって進化した？―モズは「はやにえ」を食べてメスの誘引に重要なさえずりの質を高める― 
    受賞者: 西田有佑;高木昌興

Published Papers

  • Daisuke Aoki, Shin Matsui, Mari Esashi, Isao Nishiumi, Junco Nagata, Masaoki Takagi
    Biological Journal of the Linnean Society 2023/09/07
  • Akira Sawada, Kiyohisa Tatematsu, Toshiyuki Kawano, Masaoki Takagi
    Ornithological Science 22 (2) 1347-0558 2023/07/26
  • Akira Sawada, Tetsuya Iwasaki, Chitose Inoue, Kana Nakaoka, Takumi Nakanishi, Junpei Sawada, Narumi Aso, Syuya Nagai, Haruka Ono, Ryota Murakami, Masaoki Takagi
    ORNITHOLOGICAL SCIENCE 22 (1) 25 - 34 1347-0558 2023/01 
    Empirical ornithologists often analyse dispersal distance by histograms separately drawn for categories of individuals (e.g., sexes), and/or by linear models with normal distribution (e.g., ANOVA). However, theoreticians describe dispersal distance by dispersal kernels with various parametric distributions. Therefore, it is a helpful exercise for empiricists to estimate dispersal kernels from field data. As a model case for such an estimation, we analysed dispersal data of the Ryukyu Scops Owls Otus elegans using a Bayesian Weibull regression model. Estimated dispersal kernels showed that males and individuals fledged from late-breeding nests had short natal dispersal distances and that no factors affected breeding dispersal significantly.
  • Akira Sawada, Tetsuya Iwasaki, Kana Akatani, Masaoki Takagi
    Ecology and Evolution 12 (12) 2045-7758 2022/12/12 
    Abstract Understanding evolutionary phenomena that involve size assortative mating requires elucidating the generating mechanisms on which assortment is based. Although various mechanisms have been suggested, their relative importance may differ across taxonomic groups. Males selecting for large, fecund females combined with the dominance of large males in the competition for females has been suggested as a major mechanism in specific groups. However, raptors do not appear to conform to this, because the selection for smallness among males (assumed in a theory of reversed sexual size dimorphism) and the selection for largeness among males (assumed in the theory of size assortative mating) are in opposite directions. We studied the assortative mating during a long‐term study of the Ryukyu Scops Owls Otus elegans interpositus. Significant assortative mating was found for culmen length (from the base to the tip of the bill) and wing length (from the bend of the wing to the tip of the longest primary). Statistical control of the spatial and temporal accessibility of potential mates did not affect the assortment. Males with short wings had slightly higher fitness components than those with long wings, and females settling early tended to have small wings. Considering that early‐settling females can preferentially choose their mates, these results suggest that smaller females have an advantage when choosing smaller males with good reproductive performance. Improved flying and hunting ability of smaller individuals may be the background of choosing smaller individuals. We propose that, not passive process like similarity between individuals and their potential mates, but active mate choice for small individuals is an explanation for the assortative mating in this owl.
  • Genetic parent-offspring relationships predict sexual differences in the contributions to parental care in the Tree Sparrow
    Haruna SAKAMOTO, Daisuke AOKI, Shingo UEMURA, Masaoki TAKAGI
    Ornithological Science 2022/12
  • Masaoki Takagi
    Journal of Field Ornithology 93 (3) 1557-9263 2022/09
  • Masaoki Takagi
    Journal of Avian Biology 2022 (7) 0908-8857 2022/07
  • Fumiaki Y. Nomano, Shin Matsui, Mariko Senda, Yuko Tsuchiya, Masaoki Takagi
    Ethology Ecology & Evolution 1 - 15 0394-9370 2022/05/10
  • Ryota Murakami, Akira Sawada, Haruka Ono, Masaoki Takagi
    Ornithological Science 21 (1) 1347-0558 2022/02/02
  • Daisuke Aoki, Yasuko Iwami, Masaoki Takagi
    ACTA ORNITHOLOGICA 56 (1) 15 - 28 0001-6454 2021/08 [Refereed]
     
    The Eurasian Jay Garrulus glandarius is a highly polytypic bird species composed of 34-36 subspecies. The contribution of formation of glacial refugia to the evolutionary process that generated its tremendous diversity has not been studied. We investigated the contribution of microrefugia to the subspeciation process of the Eurasian Jay in the Japanese archipelago. By assessing genetic diversity and reconstructing a mitochondrial phylogenetic tree, we asked whether divergence of a subspecies on a peripheral island (Sado Island) from the subspecies on the mainland of the Japanese archipelago (Honshu and Kyushu, hereafter mainland) occurred via formation of a microrefugium outside the mainland macrorefugia. We also assessed morphological differences between the Sado Island and mainland jay populations. We tested whether the observed morphological differences can be explained by adaptation of the Sado Island population to a species-poor microrefugium. Genetic analyses inferred that the Sado Island population survived in a refugium outside the mainland macrorefugia from around the late Middle to Late Pleistocene. The morphology of the Sado Island jay population was characterized by greater trait variance, larger body size, and a disproportionately large bill when compared with the mainland population. These results are consistent with the expected patterns of morphological evolution in microrefugia with reduced species diversity. We suggest the importance of ecological release in a microrefugium on Sado Island for the evolution of geographical variation of the Eurasian Jay in the Japanese archipelago. This is the first study to assess the significance of microrefugia for the diversification of the Eurasian Jay.
  • Akira Sawada, Tetsuya Iwasaki, Chitose Inoue, Kana Nakaoka, Takumi Nakanishi, Junpei Sawada, Narumi Aso, Syuya Nagai, Haruka Ono, Masaoki Takagi
    Population Ecology 63 (3) 204 - 218 1438-3896 2021/07/21 [Refereed]
     
    Abstract 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.
  • Daisuke Aoki, Haruna Sakamoto, Munehiro Kitazawa, Alexey P. Kryukov, Masaoki Takagi
    ECOLOGY AND EVOLUTION 11 (11) 6066 - 6079 2045-7758 2021/06 [Refereed]
     
    Long-distance dispersal (LDD) outside a species' breeding range contributes to genetic divergence. Previous phylogeographic studies of migratory bird species have not discriminated LDD from vicariant speciation in their diversification process. We conducted an integrative phylogeographic approach to test the LDD hypothesis, which predicts that a Japanese migratory bird subspecies diverged from a population in the coastal region of the East China Sea (CRECS) via LDD over the East China Sea (ECS). Haplotype networks of both mitochondrial and nuclear genes of its three subspecies were reconstructed to examine whether the Japanese subspecies of the Brown Shrike (Lanius cristatus superciliosus) diverged from an ancestral CRECS population. A species distribution model (SDM) for the Japanese subspecies was constructed using bioclimatic variables under the maximum entropy algorithm. It was projected backwards to the climate of the last glacial maximum (LGM) to infer the candidate source area of colonization. A migratory route of L. c. superciliosus, which possibly reflects a candidate past colonization route, was tracked by light-level geolocators. Molecular phylogenetic networks suggest that the Japanese subspecies diverged from a population in the CRECS and maintained anciently diverged haplotypes. The SDM inferred that the emerged continental shelf of the ECS and the present CRECS were suitable breeding areas for the Japanese subspecies during the LGM. A major migratory route for L. c. superciliosus was inferred between the CRECS and the Japanese archipelago across the ECS. Our integrative approach supported the LDD hypothesis for divergence of the Japanese subspecies of the Brown Shrike. Shrinkage of the ECS may have been responsible for successful population establishment, due to a sufficient number of migrants overshooting to the Japanese archipelago from the CRECS. Our framework provides a new phylogeographic scenario for this region. Discriminating LDD and vicariance models helps improve our understanding of the phylogeographic histories of migratory species.
  • Akira Sawada, Kana Akatani, Masaoki Takagi
    Adea 21 (3) 1  0373-2266 2021 [Refereed]
  • Reversed sexual size dimorphism in the Ryukyu Scops Owl Otus elegans on Minami-daito Island
    Akira Sawada, Tetsuya Iwasaki, Taro Matsuo, Kana Akatani, Masaoki Takagi
    ORNITHOLOGICAL SCIENCE 20 (1) 2021/01 [Refereed][Not invited]
  • Daisuke Aoki, Shin Matsui, Mari Esashi, Isao Nishiumi, Junco Nagata, Masaoki Takagi
    Biological Journal of the Linnean Society 0024-4066 2020/12/24 
    Abstract Founder effects and recurrent immigration are two major factors that might potentially contribute to genetic differentiation and population persistence in the early stage of remote island colonization. However, their relative importance remains controversial. By conducting population genetic analyses of four remote island populations of the bull-headed shrike (Lanius bucephalus) established naturally within several decades in Japan, we examined the contributions of founder effects and recurrent immigration to these island populations. Based on the standard genetic indices and population structure analyses using 15 microsatellite loci, we suggested island-specific scenarios of colonization. Notably, the founder effect strongly influenced genetic differentiation in the population on the most remote oceanic island, Chichi-jima Island, which, however, became extinct 20 years after colonization, possibly owing to a lack of recurrent immigration. In contrast, another oceanic island, Minami-Daito Island, was probably subjected to multiple recurrent immigration events from the mainland, which obscured any genetic differentiation previously established by the founder effect. Temporal samples collected over 8 years on this island confidently supported this scenario. Underlying the island-specific scenarios of colonization, we provide evidence that recurrent immigration strongly affected the population persistence, overwhelming the initial founder effects. We argue for the importance of recurrent immigration even in colonization of highly remote islands.
  • Akira Sawada, Haruko Ando, Masaoki Takagi
    JOURNAL OF EVOLUTIONARY BIOLOGY 33 (6) 762 - 772 1010-061X 2020/06 [Refereed][Not invited]
     
    How mate preferences evolve in the first place has been a major conundrum for sexual selection. Some hypotheses explaining this assume fitness benefit derived from subsequent generations. Major histocompatibility complex (MHC)-based mate choice is a representative example of the mate choice that is associated with such trans-generational mechanisms. To provide evidences for fitness benefit of MHC-based mate choice, previous studies assessed the association between own MHC genotype and own fitness components. However, the association between MHC-based mate choice in the parental generation and fitness components in the resultant offspring generation has only rarely been measured in wild populations. Focusing on the isolated population of the monogamous Ryukyu Scops Owl (Otus elegans interpositus) on Minami-daito Island, Japan, we found evidence of MHC-based mate choice. However, we found no evidence of MHC-based mate choice increasing own reproductive success or offspring survival. This is a rare case study that directly examines the existence of the trans-generational indirect benefit of MHC-based mate choice for genetic compatibility from trans-generational data in a wild bird population. By investigating the fitness benefits of mate choice, this study serves to facilitate our understanding of the evolution of MHC-based mate choice.
  • Yuusuke Nishida, Masaoki Takagi
    BIRD STUDY 67 (2) 181 - 189 0006-3657 2020/04 [Refereed][Not invited]
     
    Capsule:Wintering male Bull-headed ShrikesLanius buchepaluspreferred vegetable fields with perch sites to search for and detect terrestrial prey, and males occupying territories with large areas of vegetable fields acquired more prey and cached more food. Aims:To better understand effects of habitat use on food acquisition and food caching of the Bull-headed Shrike, we investigated relationships between habitat quality (measured through foraging-site selection and foraging success) and food caching during the non-breeding season. Methods:We monitored 66 territorial male shrikes during the non-breeding season from 2014 to 2016, and collected data on foraging-site selection, foraging success, and food caching. Results:Our field observations showed that male shrikes preferred to forage over vegetable fields and that males occupying territories incorporating large areas of that habitat were able to acquire more food items and store more food caches in their territories during the nonbreeding season. Conclusion:We suggest that for male Bull-headed Shrikes, a winter-breeding food-storing passerine, the quality of habitat in the nonbreeding season has the potential to affect their subsequent fitness.
  • Shingo Uemura, Ayumu Hamachi, Kunihiro Nakachi, Masaoki Takagi
    ORNITHOLOGICAL SCIENCE 18 (2) 215 - 219 1347-0558 2020/01 [Refereed][Not invited]
     
    The migratory strategies of kingfishers are poorly understood. In the first study of its kind, by means of Global Positioning System data loggers, we were able to describe the migration and wintering sites of the Ruddy Kingfisher Halcyon coromanda population breeding on Miyako Island, Japan. Birds were found to reach altitudes of almost 4,000 m during their migration to winter on Polillo and Tablas islands in The Philippines.
  • Kana Akatani, Masaoki Takagi
    WILSON JOURNAL OF ORNITHOLOGY 131 (4) 828 - + 1559-4491 2019/12 [Refereed][Not invited]
     
    We describe the remigial and rectricial molt sequences of a Ryukyu Scops-Owl (Otus elegans) held in captivity on Minami-daito Island, Nansei Islands, southern Japan. The owl completely shed its remiges and rectrices during its preformative molt as well as during its definitive prebasic molts in 3 consecutive years. In the preformative molt, the primaries were all shed during October, November, and December, in distal order from Pl. Although all 4 groups of secondaries were shed in proximal order, the sequence may have been caused by adventitious shedding under captive conditions. During definitive prebasic molt, the primaries were shed in distal order during the period from June to September. The secondaries were shed from 3 nodes in 4 feather groups; 3 groups were shed in proximal order, but the remaining group was shed in distal order. The primary coverts were shed in exact sequence with their corresponding primaries during the definitive prebasic molt, but in a different sequence during the preformative molt. Whereas the greater coverts were shed irregularly during the early part of the primary covert molt, the median coverts were shed during the first half of the primary covert molt. The alula feathers were shed distally over a period of weeks. The right rectrices were shed in irregular order over a short period (12 days) and the left rectrices were shed over a long period (at least 82 days). The shedding sequence of the captive Ryukyu Scops-Owl basically followed the known pattern previously observed in Strigidae species. The captive individual underwent a complete molt when it was a juvenile as a result of being provided with sufficient food, and presumably because of the lower energy demands of being in a cage.
  • Shingo UEMURA, Kunihiro NAKACHI, Ayumu HAMACHI, Masaoki TAKAGI
    Japanese Journal of Ornithology 68 (2) 379 - 381 0913-400X 2019/10/25
  • Yuusuke Nishida, Masaoki Takagi
    Animal Behaviour 152 29 - 37 0003-3472 2019/06 [Refereed][Not invited]
  • A. Sawada, T. Iwasaki, M. Takagi
    Journal of Zoology 307 (3) 159 - 166 0952-8369 2019/03/13 [Refereed][Not invited]
  • Kana AKATANI, Masaoki TAKAGI
    Journal of the Yamashina Institute for Ornithology 50 (2) 125 - 128 1348-5032 2019/02/28 [Refereed][Not invited]
  • 沖縄県池間島におけるアカノドカルガモAnas luzonicaの観察記録
    植村慎吾, 仲地邦博, 浜地歩, 高木昌興
    日本鳥学会誌 = Japanese journal of ornithology 68 (2) 2019 [Refereed][Not invited]
  • Vocalizations of the Ryukyu Scops Owl: individually recognisable and stable
    Masaoki TAKAGI
    Bioacoustics https://doi.org/10.1080/095246 0952-4622 2018/11 [Refereed][Not invited]
  • Yusuke Nishida, Takagi Masaoki
    Journal of Avian Biology https://doi.org/10.1111/jav.01 1600-048X 2018/07 [Refereed][Not invited]
  • Junpei Sawada, Masaoki Takagi
    Ornithological Science 17 (1) 109 - 112 1347-0558 2018 [Refereed][Not invited]
     
    We found five Ruddy-breasted Crake Porzana fusca nests in a swamp among emergent vegetation, and one in a dry sugarcane field more than 500 m (radius) from any swamp or pond, on Minami-daito Island. Nests were saucer-shaped. All of the nests in the swamp fledged chicks. It is assumed that nesting in such habitat renders nests safe from ground predators such as introduced weasels and feral cats. Roosts were similar in structure to nests, but lacked lining. It is inferred from one observation that males and females roost together at night before the egg-laying period.
  • Akira Sawada, Takeshi Yamasaki, Yasuko Iwami, Masaoki Takagi
    Ornithological Science 17 (1) 45 - 54 1347-0558 2018 [Refereed][Not invited]
     
    Morphological differentiation of island-dwelling organisms provides model systems for studying evolution. Computed tomography (CT) scanning is an entirely non-destructive technique that provides detailed three-dimensional (3D) images of physical structures. Geometric morphometrics has been increasingly used in avian morphology studies by analyzing 3D data obtained from CT scans. We used geometric morphometrics to evaluate the morphological details of the skulls of three, genetically distinct, island populations of the Ryukyu Scops Owl Otus elegans: O. e. elegans from the northern part of the Ryukyu Archipelago, O. e. elegans from the southern part of the Ryukyu Archipelago, and O. e. interpositus from Minami-daito Island. Skulls were scanned using an X-ray CT system and the digitized 3D coordinates of 16 landmarks for each skull were analyzed in order to describe geometric morphometric features. O. e. interpositus was found to have a significantly smaller skull than either population of O. e. elegans. From principle component analysis of shape variation, we also found that the skull shape of O. e. interpositus differed significantly from both the northern and southern groups of O. e. elegans. This difference was in terms of PC1, which mainly represented relative anteroposterior length, and angle of the orbit. We inferred that the small skull of O. e. interpositus is partly a consequence of the particular founders of the population, or evolutionary selection that has taken place on Minami-daito Island and that the distinctive shape of the skull of O. e. interpositus is partly a consequence of adaptations for foraging efficiency, or of morphological integration.
  • Shin Matsui, Masaoki Takagi
    ORNITHOLOGICAL SCIENCE 16 (1) 79 - 86 1347-0558 2017/01 [Refereed][Not invited]
     
    Since the 1970s the Bull-headed Shrike Lanius bucephalus has established a breeding population on the Daito Islands. The islands represent the southwestern limit of the species' breeding range. We investigated the habitat selection of this isolated population during the 2003 breeding season in the agricultural landscape of Minami-daito Island. A comparison of habitat types around shrike nests and randomly selected points, showed that shrikes largely foraged in sugarcane fields and utilized fences and utility wires as suitable perch sites. Our results suggest that it is the open, cultivated areas (sugarcane has been grown on the island since 1900) that have provided suitable habitat for the Bull-headed Shrike allowing it to establish a breeding population on the Daito Islands.
  • Hamachi Ayumu, Uemura Shingo, Nakachi Kunihiro, Takagi Masaoki
    Bird Research 特定非営利活動法人バードリサーチ 13 (0) S27 - S33 1880-1587 2017 [Refereed][Not invited]
     

    We observed the occurrence of Large Hawk-Cuckoos Hierococcyx sparverioides and Asian Koels Eudynamys scolopaceus from 2015-2017 at the Oono Forest in Miyako Island, Okinawa Prefecture, Japan. Two Asian Koels (a male and a female) were present for more than two months during the breeding season of 2015, and this suggests that they may have attempted breeding, although there was no confirmed observation of reproductive behavior. These two species are increasingly recorded in Japan, which suggests that these species are expanding their distribution northward.

  • Masaoki Takagi, Takema Saitoh, Noriyuki Yamaguchi, Hiroto Okabe, Isao Nishiumi, Masayoshi Takeishi
    ORNITHOLOGICAL SCIENCE 14 (1) 53 - 59 1347-0558 2015/01 [Refereed][Not invited]
     
    A nest of the Ryukyu Scops Owl Otus elegans was found on Okinoshima (Okino Island), Fukuoka Prefecture, Japan (34.24 degrees N, 130.10 degrees E), in the Tsushima Strait, on 28 July 2013. The breeding pair and their three owlets were caught and their identity confirmed genetically using the BOLD System for COI in the mitochondrial genome. Their calls and external morphological measurements also accorded with what is known of the species. We estimated that at least 23 territorial males inhabit the Island. Okinoshima lies 490 km beyond the previously known northern limit of the species' distribution.
  • YOSHINO Tomoo, HAMA Natsuki, ONUMA Manabu, TAKAGI Masaoki, SATO Kei, MATSUI Shin, HISAKA Mariko, YANAI Tokuma, ITO Haruo, URANO Nobutaka, OSA Yuichi, ASAKAWA Mitsuhiko
    酪農学園大学紀要 自然科学編(Web) 38 (2) 139 - 148 2187-0500 2014/04 [Refereed][Not invited]
  • Masaoki Takagi
    WILSON JOURNAL OF ORNITHOLOGY 125 (2) 358 - 369 1559-4491 2013/06 [Refereed][Not invited]
     
    The Ryukyu Scops Owl, Otus elegans, is distributed over a 1,200-km area, only inhabiting islands. Within this range, I studied this species across 20 continental islands in the Ryukyu Archipelago and two oceanic islands. Although most studies recently use quantitative continuous measurements of many specific aspects of the vocalization, I introduced a new method, "typological analysis" to visually classify variation of spectrograms according to the shape of syllable in the owl species, examining their dialects in relation to their geographical distribution. In the typological analysis, hoot, syllable, and element types were defined according to the number of syllables, the degree of timescale overlap of the first and second elements in the second syllable, and relative differences of duration and frequency of two elements in the second syllable, respectively. Although frequencies of hoot and element types in each island population were significantly different between the island groups north and south of the Kerama Gap across the archipelago, hoot and element types were shared between the island groups. Furthermore, typological variation occurred in syllable types, however there were no differences in frequencies of syllable types between the island groups. Geographic structure in vocal parameters as steep clines with stepped variation is represented as a dialect. According to the definition, this study found that no unique dialects in hoots occurred between the different island populations of Ryukyu Scops Owls. The Kerama Gap might act as a biogeographical barrier, contributing to the differentiation between owl hoots according to spectrotemporal analyses; however, the typological analysis detected the distribution of typological characteristics of hoots on the small islands north of the Kerama Gap that contradicts this concept of a biogeographical barrier. Because the typological analysis needs to visually examine each individual by careful attention to detail, it is a good method for discovering minor geographic variations and patterns in bird vocalizations.
  • Naoki Tomita, Masaoki Takagi
    WILSON JOURNAL OF ORNITHOLOGY 125 (1) 121 - 127 1559-4491 2013/03 [Refereed][Not invited]
     
    We investigated the amount of time Black-tailed Gulls (Lams crassirostris) incubated and its effects on hatching interval within two-egg clutches. Incubation patterns were classified into three categories (rising, steady, or pulsed) related to daily change of incubation rate until clutch completion. Hatching intervals (mean +/- SD, 0.95 +/- 0.76 days) were significantly shorter than laying intervals (2.56 +/- 0.75 days). There was a significant positive relationship kbetween incubation rate on the day when the first egg was laid (day 1) and hatching interval (Spearman's r(s) = 0.677, P = 0.016). The incubation rate on day 1 also increased (Spearman's r(s) = 0.521, P = 0.039) as the breeding season progressed, and hatching interval expanded (Kruskal-Wallis test: chi(2)(2) = 8.3, P = 0.016, range = 0-2 day). Thus, the amount of time gulls spent incubating on day 1 was important in affecting hatching intervals and suggested that parents partially controlled hatching intervals with seasonal change by timing of the onset of incubation in this species. Received 27 November 2011. Accepted 30 September 2012.
  • HIROWATARI Toshiya, MATSUI Shin, TAKAGI Masaoki, NASU Yoshitsugu, UEDA Keisuke
    Cho to Ga 日本鱗翅学会 63 (3) 107 - 115 0024-0974 2012/09/30 [Refereed][Not invited]
     
    Lepidoptera emerged from nests of the Bull-headed Shrike, Lanius bucephalus Temminck and Schlegel, in Minamidaitojima, Japan was investigated. A total of 56 individuals belonging to six species, Heleanna fukugi Nasu (Tortricidae), Opogona sacchari (Bojer)(Tineidae), Erechthias minuscula (Walsingham) (Tineidae), Anatrachyntis sp. (Cosmopterigidae), Ascalenia sp. (Cosmopterigidae), and Simplicia mistacalis (Guenee) (Noctuidae), were identified. One species H. fukugi, and possibly Ascalenia sp., were considered to utilize the nest as a pupation site, and larvae of the other 4 species were inferred to feed on dead plant material of the nests. Emergence from a bird nest is firstly reported in Simplicia mistacalis and Erechthias minuscula, and the latter species is recorded from Japan for the first time. Species composition of emerged moths differed from previously reported ones, which is characterized by a lack of keratinophagous and chitinophagous tineid moths such as Monopis and Niditinea species.
  • Shin Matsui, Masaoki Takagi
    IBIS 154 (3) 621 - 625 0019-1019 2012/07 [Refereed][Not invited]
     
    Appropriate nest-site selection is one of the most important ways to minimize loss of reproductive investment due to predation. We determined the environmental characteristics associated with nest predation during the incubation and nestling periods of arboreal nesting Bull-headed Shrikes on the oceanic Minami-Daito Island where the predator community has low species diversity and includes only three introduced mammals: Ship Rat Rattus rattus, Japanese Weasel Mustela itatsi and Feral Cat Felis catus. Egg predation declined with increasing grassland cover around nests, whereas nestling predation declined with increasing nest concealment and nest height. Our results suggest that effective nest-site characteristics for avoiding nest predation differ during the incubation and nestling periods and are dependent on the predator species and their search strategies, at least in habitats with low predator species diversity.
  • Sayaka Horie, Masaoki Takagi
    IBIS 154 (2) 285 - 295 0019-1019 2012/04 [Refereed][Not invited]
     
    Age-related improvement in reproductive success is widely observed in birds, and the mechanisms by which productivity is enhanced have received considerable attention. However, little is known about how parental age affects the loss of eggs or nestlings despite the fact that age effects on nesting success are often reported. We examined parental age effects on reproductive success in relation to the avoidance of nest predation in an island subspecies of the Japanese White-eye, the Daito White-eye Zosterops japonicus daitoensis. Clutch size and annual number of breeding attempts did not differ between parental age classes. Reproductive success was affected only by male age through an increase in nesting success. Nest failure was attributed only to predation in this species and nest concealment and nest height were important nest characteristics promoting successful fledging. Older males built their nests in more concealed and higher positions than first-year birds, regardless of vegetation status around the nest. Analysis of individual birds suggested that by shifting the nest to a safer position, male White-eyes achieved higher nesting success than in the previous year. Of three hypotheses of age-related improvement in reproductive success considered, our data favoured the hypothesis that as individuals grow older, their breeding competence improves.
  • Matsui Shin, Tsuchiya Yukoi, Hisaka Mariko, Takagi Masaoki
    Journal of Yamashina Institute for Ornithology Yamashina Institute for Ornitology 44 (1) 31 - 35 1348-5032 2012 [Refereed][Not invited]
     
    The hatching pattern of many altricial passerine birds is asynchronous. We describe the degree of hatching asynchrony of each brood and the resulting size hierarchy at five days after the first egg hatched in the Bull-headed Shrike Lanius bucephalus on Minami-daito Island, Japan. Comparison of body mass ratios of each nestling to the largest nestling in a brood at five days after the first egg hatched showed that there was little overlap in terms of size among the nestlings hatched on the same day as the first egg (95% CI: 0.94–0.98), those hatched one day later (0.73–0.83), and those hatched two or more days later (0.52–0.72). We suggest that the size hierarchy caused by hatching asynchrony is detectable from five days after first egg hatched.
  • Masaoki Takagi, Kana Akatani
    ORNITHOLOGICAL SCIENCE 10 (2) 151 - 156 1347-0558 2011/12 [Refereed][Not invited]
     
    We identified the diet of owlets of the Daito subspecies of the Ryukyu Scops Owl Otus elegans interpositus on Minami-daito Island during late May and early June 2009, by means of high-resolution color photography. Cockroaches were provided by parents to their young at all eight nests studied, and contributed the largest single component of the diet (33%). Orthoptera species, which inhabited open grassland habitats, constituted >20% of the total occurrences in the diet of owlets. It is suggested that Ryukyu Scops Owls depend heavily on food items obtained from habitats that have been modified by human activity on Minami-daito Island. Diets for owlets differed widely among nests, and the differences were considered to result from individual differences among parents and/or the environments surrounding each nest.
  • Kana Akatani, Taro Matsuo, Masaoki Takagi
    JOURNAL OF RAPTOR RESEARCH 45 (4) 315 - 323 0892-1016 2011/12 [Refereed][Not invited]
     
    We studied the nest sites, diet, and habitat use of the endemic population of the Daito Scops Owl (Otus elegans interpositus), a subspecies of the Elegant Scops Owl (O. elegans), on a small oceanic island, Minami-daito, in the northwestern Pacific Ocean. We also investigated the relationships between habitat characteristics and breeding performance in the fragmented and developed habitats on the island. Most owls used nest cavities in introduced casuarina (Casuarina spp.) trees (n = 30), whereas a few owls used vertical hollows in broken native fan palm (Livistona chinensis; n = 2) as their nest sites. Owls fed on prey inhabiting both forests and open areas, including spiders (Heteropoda), cockroaches (Blattodea), grasshoppers (Orthoptera) and geckos (Gekkonidae). We tracked 17 territorial males and seven females using radiotelemetry in 2002-07. More than half of the owls selected Fins forests during the breeding season. During the nonbreeding season, most owls selected edges between forests and open areas such as grass-lands and sugar cane fields. Owls with more edge habitat within their home ranges laid eggs earlier (n = 88 breeding attempts) than those with smaller amounts of edge. Daito Scops Owls exhibited behavioral flexibility in their use of human-altered habitats on Minami-daito Island, which may have contributed to their avoidance of extinction.
  • Masaoki Takagi
    IBIS 153 (4) 779 - 788 0019-1019 2011/10 [Refereed][Not invited]
     
    The distribution of species and species diversity can be affected by vicariance or dispersal. To understand their role in shaping species distribution and population structure these two processes must be estimated within and among populations. I analysed large-scale variation in the call structure of the Ryukyu Scops Owl Otus elegans. This owl is distributed over a 1200-km range, and only inhabits islands. Within this range, I studied this species across 22 continental islands of the Ryukyu Archipelago and two oceanic islands. The study aimed to assess whether there is variation in the acoustic structure of Owl hoot calls within islands, among major groups of islands and across a large area comprising a major biogeographical barrier (the Kerama Gap). The acoustic structure of calls was homogeneous within islands and among major island-groups. Acoustic differentiation, however, increased over longer geographical distances of up to about 1200 km. The acoustic structure of hoots of the Ryukyu Scops Owl populations was clearly divided into two groups, north and south of the Kerama Gap. It is suggested that the Kerama Gap acted as a biogeographical barrier and contributed to the differentiation between the two major island-groups. It is likely that this difference developed during the fragmentation of a widespread ancestral population by vicariant isolating events. There was also evidence of an effect of dispersal on vocal differentiation in subspecies inhabiting the two oceanic islands.
  • Naoki Tomita, Kentaro Kazama, Hidetsugu Sakai, Megumi Sato, Atsushi Saito, Masaoki Takagi, Yasuaki Niizuma
    ORNITHOLOGICAL SCIENCE 10 (1) 21 - 25 1347-0558 2011/06 [Refereed][Not invited]
     
    Mother birds can enhance growth and/or survival of chicks by supplying energetic and hormonal resources to the egg yolk (i.e. maternal effect). In several bird species, mothers supply higher level of testosterone to the eggs laid later within the clutch and enhance the growth of the chick to compensate for the disadvantage of the later hatching. As same as this within-clutch mechanism, mothers breeding later in the season can be expected to supply higher level of testosterone to the clutch. However, among-clutch seasonal variation in yolk testosterone levels has been rarely described. Here, we investigated among-clutch seasonal variation in the yolk testosterone level in Black-tailed Gulls Larus crassirostris, as well as within-clutch variation. Mean yolk testosterone level of eggs laid later within the clutch ("b-eggs") was significantly higher than that of eggs laid earlier ("a-eggs"). The yolk testosterone levels of both a- and b-eggs of later breeders were significantly higher than those of earlier ones, while this trend was not observed in mean egg mass. Our results indicate that mothers establishing the clutch later in the season would invest more maternal testosterone into the clutch.
  • Matsui Shin, Kobayashi Sayaka, Takagi Masaoki
    Jpn. J. Ornithol. 日本鳥学会 60 (2) 262 - 265 0913-400X 2011 [Refereed][Not invited]
  • Shin Matsui, Mariko Hisaka, Masaoki Takagi
    BIRD CONSERVATION INTERNATIONAL 20 (1) 34 - 42 0959-2709 2010/03 [Refereed][Not invited]
     
    The introduction of exotic rats Ratios spp. is one of the most important factors contributing to the reduction in avian diversity and extinctions on oceanic islands. However, little is known about factors other than predation, which are associated with the loss of island biodiversity. We report that introduced Ship Rats Ratios ratios constructed arboreal dome-shaped nests and secondarily used open-cup nests of the Bull-headed Shrike Lanius bucephalus for roosting or rearing young in trees within hedgerows along sugarcane fields of Minami-daito Island (northwest Pacific). We found that temporal nest utilization by Ship Rats forced Bull-headed Shrikes to abandon their nests before egg-laying. We suggest that kleptoparasitism applies to the interaction between Bull-headed Shrikes and Ship Rats, which usurp shrike nests during their breeding period. It is necessary to consider the potential effects of introduced Ship Rats on insular avian communities not only through predation but also through interspecific interaction over nest-sites.
  • Mao Nakamura, Yoshihide Takaki, Sayaka Mori, Keisuke Ueda, Isao Nishiumi, Masaoki Takagi, Richard A. Noske, Kazuhiro Eguchi
    Journal of the Yamashina Institute for Ornithology 42 (1) 47 - 64 1882-0999 2010 [Refereed][Not invited]
     
    We conducted a study to clarify the impact of bush fires on the structure of non-breeding flocks of the Red-backed Fairy-wren Malurus melanocephalus cruentatus in the Australian monsoon tropics. Overall, the mean group size was large in the mid dry season, becoming smaller with the progress of season. Large groups occurred at burnt sites, while at unburnt sites group size was smaller owing to a higher proportion of pair-sized groups. Bush fire destroyed habitat and forced resident birds to emigrate. Conversely, unburnt sites were used as a refuge during fires. However, in the non-breeding season, such stable habitats were occupied by stable and small-sized groups and were already saturated. Therefore, individuals that immigrated into these habitats during fires were forced to emigrate again. After a fire, many birds invaded burnt sites from the surrounding area and aggregated in large but unstable flocks that consequently diminished due to the individual separation of young males just before the breeding season. Bush fires resulted in the reorganisation of groups and re-establishment of territory. © Yamashina Institute for Ornithology.
  • Naoki Tomita, Sayaka Someya, Isao Nishiumi, Osamu Hasegawa, Yukiko Inoue, Masaoki Takagi
    Journal of the Yamashina Institute for Ornithology 42 (1) 79 - 90 1882-0999 2010 [Refereed][Not invited]
     
    We reported characteristics of external morphology and DNA sequence from the carcass of a large-sized gull with yellow legs recovered at Teuri Island, Hokkaido, Japan. According to Olsen & Larsson (2003), based on the tone of the upperwings and mantle and the pattern of the primary tips the carcass sample was identified as Larus heuglini, but could not be identified at the subspecies level. Sequence variation in the cytochrome b and control region gene of the carcass sample agreed with common types of closely-related taxa (fuscus, heuglini, barabensis, or taimyrensis). Our study underscored the diffculty in identifying large white-headed gulls accurately even when based on quantitative data such as those obtained from carcass samples or DNA sequences. Further quantitative studies on inter- and intra-population variations in external morphology of birds at each breeding site are needed. © Yamashina Institute for Ornithology.
  • Yoshio Tsuda, Shin Matsui, Atsushi Saito, Kana Akatani, Yukita Sato, Masaoki Takagi, Koichi Murata
    JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 25 (3) 279 - 284 8756-971X 2009/09 [Refereed][Not invited]
     
    The seasonal prevalence and spatial distribution of mosquitoes were examined as part of an avian malaria study on the oceanic island of Minami-Daito Island, Japan. Because dry ice was not available in this study, yeast-generated CO(2) was used to attract biting mosquitoes. Adult mosquitoes were collected biweekly using battery-operated traps enhanced with yeast-generated CO, and a gravid trap from March 2006 to February 2007. The CO-baited traps were distributed in 4 different habitats: sugar cane field, forest and vegetation ring, residential area, and swamp area. At 3 collection sites beside sugar cane fields, traps were fixed at 2 different heights (3 and 6 in above the ground). A total of 1,437 mosquitoes of the following 9 species were collected: Culex quinquefasciatus, Aedes albopictus, Coquillettidia sp., Mansonia uniformis, Culex rubithoracis, Armigeres subalbatus, Lutzia fuscanus, Aedes daitensis, and Aedes togoi. Among them, Cx. quinquefasciatus, Ae. albopictus, and Coquillettidia sp. were dominant. The high density and wide distribution of Cx. quinquefasciatus throughout the island Suggested the importance or this species as a principal vector of avian malaria on the island.
  • Naoki Tomita, Yasuaki Niizuma, Masaoki Takagi, Motohiro Ito, Yutaka Watanuki
    ECOLOGICAL RESEARCH 24 (1) 157 - 162 0912-3814 2009/01 [Refereed][Not invited]
     
    Sea-surface temperature (SST) directly and indirectly affects the distribution and abundance of prey species for seabirds, so we expect variation in SST to be associated with variation in seabird life history traits. In black-tailed gulls (Larus crassirostris) at Teuri Island in northern Hokkaido, Japan, we investigated the diet of the gulls prior to egg laying in 2004 and 2005, and examined the influences of SST in March or April, when the gulls congregate in the colony, on egg-laying parameters using 13 years of data (1992-2004). The gulls fed on krill (Thysanoessa inermis) and fish prior to the egg laying. Mean first egg dates and clutch sizes were significantly and quadratically related to SST anomalies in March, but were not influenced by SST anomalies in April. There was no significant effect of SSTs in either March or April on egg volume. Sea-surface temperature anomalies in March of the years of early laying (-1 to 1A degrees C) were higher than those in 2001 (-2.2A degrees C), but lower than those in 1992 (+1.2A degrees C) and 2004 (+1.1A degrees C). Thysanoessa inermis congregates to spawn at the sea surface, when SSTs rise 3-4A degrees C. Thus, a mismatch between food availability and the timing of egg production in the gulls could have occurred in these 3 years. This study suggests that SST fluctuations prior to laying are important in breeding success of black-tailed gulls.
  • Shin Matsui, Kana Akatani, Sayaka Horie, Masaoki Takagi, Tomonori Kikuchi
    Ornithological Science 8 (1) 81 - 86 1347-0558 2009 [Refereed][Not invited]
     
    This report describes, for the first time, harmful effects of invasive Yellow Crazy Ants Anoplolepis gracilipes on wild birds in Japan. We observed fledglings of Bull-headed Shrike Lanius bucephalus and Daito White-eye Zosterops japonicus daitoensis caused fatal injuries by ants on the ground on Minami-daito Island. We compared reproductive behaviors of Daito Scops Owl Otus elegans interpositus in a cavity with ants and cavities without ants and found that while reproductive success did not differ between them, parental females in a cavity with ants more frequently interchanged their nest site than those in cavities without ants. © 2009, The Ornithological Society of Japan. All rights reserved.
  • Takagi Masaoki
    Jpn. J. Ornithol. 58 (1) 1 - 17 0913-400X 2009 [Refereed][Not invited]
  • Hiroko Ejiri, Yukita Sato, Emi Sasaki, Daisuke Sumiyama, Yoshio Tsuda, Kyoko Sawabe, Shin Matsui, Sayaka Horie, Kana Akatani, Masaoki Takagi, Sumie Omori, Koichi Murata, Masayoshi Yukawa
    JOURNAL OF VETERINARY MEDICAL SCIENCE 70 (11) 1205 - 1210 0916-7250 2008/11 [Refereed][Not invited]
     
    Several species of birds in Minami Daito Island, an oceanic island located in the far south from the main islands of Japan, were found to be infected with avian Plasmodium. However, no vector species of the avian malaria in this island have been revealed yet. To Speculate potential vectors, we collected mosquitoes there and investigated using a PCR procedure whether the mosquitoes harbor avian malaria or not. Totally 1,264 mosquitoes including 9 species were collected during March 2006 to February 2007. The mosquitoes collected were stored every species, sampled date and location for DNA extraction. Fifteen Out of 399 DNA samples showed positive for the partial mtDNA cytb gene of avian Plasmodium. Estimated minimum infection rate among collected mosquitoes was 1.2% in this study. Four species of mosquitoes; Aedes albopictus, Culex quinquefasciatus, Liatzia fuscanus and Mansonia sp. had avian Plasmodium gene sequences. Detected DNA sequences from A. albopictus and L. fuscanus were identical to an avian Plasmodium lineage detected ill bull-headed shrike (Lanius bucephalus) captured in the island. Different sequences were detected from C. quinquefasciatus, which were corresponding to all avian Plasmodium from a sparrow (Passer montanus) and Plasmodium gallinaceum. Our results suggest that A. albopictus, Lutzia fuscanus, C. quinquefasciatus, and Mansonia sp. Could be potential vectors of avian malaria in Minami Daito Island. This study was the first report of molecular detection of avian Plasmodium from mosquitoes in Japan.
  • Koichi Murata, Ryosuke Nii, Saori Yui, Emi Sasaki, Satoshi Ishikawa, Yukita Sato, Shin Matsui, Sayaka Horie, Kana Akatani, Masaoki Takagi, Kyoko Sawabe, Yoshio Tsuda
    JOURNAL OF VETERINARY MEDICAL SCIENCE 70 (5) 501 - 503 0916-7250 2008/05 [Refereed][Not invited]
     
    Haemosporidian parasites infection among wild birds inhabiting Minami-daito Island was studied. Blood films from 183 birds representing 4 species of 4 families were examined microscopically. Avian haemosporidian parasites were detected in 3 species with an overall prevalence of 59.6%. None of the 30 Daito scops owls (Otus scops interpositus) examined were infected. Either Haemoproteus sp. or Plasmodium sp. infection was found in 14 of 31 (45.2%) Borodino islands white-eyes (Zosterops japonicus daitoensis). Plasmodium Sop. were found in 94 of 102 (92.2%) bull-headed shrikes (Lanius bucephalus) and 1 of 20 (5%) tree sparrows (Passer montanus).
  • 南大東島で採集された蚊における鳥マラリア原虫遺伝子の検出
    江尻寛子, 佐藤雪太, 佐々木絵美, 仁位亮介, 津田良夫, 松井 晋, 高木昌興, 湯川眞嘉, 村田浩一
    日本獣医寄生虫学会誌 6 (1) 38  2008/02 [Refereed][Not invited]
  • Responses in breeding behaviour of Black-tailed Gull Larus crassirostris to different marine environments.
    KAZAMA Kentaro, TOMITA Naoki, Ito Motohiro, NIIZUMA Yasuaki, TAKAGI Masaoki, WATANUKI Yutaka
    Proceeding of International Symposium on the Origin and Evolution of Natural Diversity 215 - 220 2008 [Refereed][Not invited]
  • 南大東島における鳥マラリア原虫の分子系統と宿主転換
    炭山大輔, 佐々木絵美, 佐藤雪太, 津田良夫, 澤邊京子, 松井 晋, 堀江明香, 高木昌興, 猪子英俊, 村田浩一
    日本獣医寄生虫学会誌 7 (1) 23  2008 [Refereed][Not invited]
  • Kazuhiro Eguchi, Noriyuki Yamaguchi, Keisuke Ueda, Hisashi Nagata, Masaoki Takagi, Richard Noske
    JOURNAL OF ORNITHOLOGY 148 S203 - S210 0021-8375 2007/12 [Refereed][Not invited]
     
    A 4-year study of cooperative breeding in the Grey-crowned Babbler Pomatostomus temporalis was conducted in the monsoon-tropics of northern Australia. Most groups comprised a single socially monogamous pair with up to seven helpers. We found no floaters. The sex ratio was almost unity for each year. Helpers included philopatric offspring, immigrating juveniles and immigrating sexually mature birds. Adults of both sexes moved frequently between groups. Pairs without helpers were unable to raise young to fledging and often divorced, suggesting that cooperative breeding was obligatory in this population. However, for groups with helpers, the group size effect was weak; there was no significant correlation between the number of fledglings and number of helpers. Breeding females exclusively contributed to incubation. Breeders contributed more to provisioning of nestlings than non-breeders. Although helpers did not enhance the total provisioning rate to nestlings, small groups should recruit helpers to maintain the group and enhance reproductive success.
  • TAKAGI Masaoki, AKATANI Kana, SAITO Atsushi, MATSUI Shin
    Ornithological Science 6 (1) 39 - 42 1347-0558 2007/07 [Refereed][Not invited]
  • MATSUI Shin, IKEDA Hiroshi, NARUSE Tohru, ASANUMA Kiyoshi, TAKAGI Masaoki
    The Biological magazine,Okinawa 沖縄生物学会 45 33 - 37 0474-0394 2007/05/31 [Refereed][Not invited]
  • Masaoki Takagi, Kana Akatanti, Shin Matsui, Atsushi Saito
    JOURNAL OF RAPTOR RESEARCH 41 (1) 52 - 56 0892-1016 2007/03 [Refereed][Not invited]
  • 南大東島で採集された蚊における鳥マラリア原虫遺伝子の検出
    江尻 寛子, 佐藤 雪太, 佐々木 絵美, 仁位 亮介, 津田 良夫, 松井 晋, 高木 昌興, 湯川 眞嘉, 村田 浩一
    日本獣医学会学術集会講演要旨集 (公社)日本獣医学会 143回 170 - 170 1347-8621 2007/03
  • Matsui S., Tsuda Y., Saito A., Akatani K., Yamauchi T., Sato Y., Takagi M., Murata K.
    Medical Entomology and Zoology 日本衛生動物学会 58 41 - 41 2007
  • YAMADA Fumihiko, TAKAGI Masaoki
    Japanese journal of ornithology 日本鳥学会 55 (2) 114 - 116 0913-400X 2006/12/22 [Refereed][Not invited]
  • MATSUI Shin, TAKAGI Masaoki, UEDA Keisuke
    Jpn. J. Ornithol. 日本鳥学会 55 (1) 29 - 31 0913-400X 2006/06/22 [Refereed][Not invited]
  • モズ（Lanius bucephalus）おけるHamatospiculum属線虫（Diplotriaenoidea上科）の濃厚寄生症例報告とその保全医学上の視点
    大沼 学, 吉野智生, 高木昌興, 松井 晋, 長嶺 隆, 川嶋貴治, 村田浩一, 桑名 貴, 浅川満彦
    日本獣医寄生虫学会誌 5 (1) 50  2006/02 [Refereed][Not invited]
  • Matsui Shin, Hisaka Mariko, Takagi Masaoki
    ORNITHOLOGICAL SCIENCE 日本鳥学会 5 (2) 227 - 229 2006 [Refereed][Not invited]
  • Y Niizuma, M Takagi, M Senda, M Chochi, Y Watanuki
    JOURNAL OF AVIAN BIOLOGY 36 (5) 421 - 427 0908-8857 2005/09 [Refereed][Not invited]
     
    Factors determining clutch size of birds have long been the central issue in studies in life histories. It is assumed that the configuration of brood patches could limit the maximum clutch size. To test this hypothesis we manipulated clutch sizes and measured egg temperature as well as reproductive consequences in black-tailed gulls Larus crassirostris, which usually lay two egg clutches and have three brood patches. Mean egg temperature in 4-egg clutches (32.6 +/- 1.0 degrees C) was significantly lower than in 2-egg (34.6 +/- 0.4 degrees C) and 3-egg clutches (34.1 +/- 0.4 degrees C), because egg temperature of the coolest egg within a 4-egg clutch was often substantially lower than the other three eggs. The proportion of eggs hatching from 4-egg clutches (11.6%) was lower than those of 2-egg (49.1%) and 3-egg clutches (52.0%). Four-egg clutches had longer incubation periods (29.6 +/- 1.3 day) than 2-egg (28.1 +/- 1.7 day) and 3-egg clutches (28.0 +/- 1.3 day). The results indicate that incubation capacity, which may be determined by the configuration of brood patches, limits the maximum clutch size in black tailed gulls, but not the actual clutch size typically laid.
  • HORIE Sayaka, MATSUI Shin, TAKAGI Masaoki
    Jpn. J. Ornithol. 日本鳥学会 54 (1) 58 - 59 0913-400X 2005/07/29 [Refereed][Not invited]
  • The timing of clutch initiation in Bull-headed Shrikes (Lanius bucephalus) in relation to re-nesting or second nesting._
    TAKAGI Masaoki
    Ornis Fennica 81: 84-90. 81 84 - 90 2004 [Refereed][Not invited]
  • M Takagi
    CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE 81 (2) 287 - 293 0008-4301 2003/02 [Refereed][Not invited]
     
    I studied the seasonal change in egg volume in Bull-headed Shrikes, Lanius bucephalus, to explore the importance of egg-volume variation within a clutch. The mean egg volume did not change over a season; however, the coefficient of variation in egg volume in six-egg clutches significantly increased in 1994 and 1995 but did not change in 1996. Peaks in arthropod biomass occurred early in the breeding seasons in 1994 and 1995, but late in the season in 1996. Higher food availability was related to a reduction in variation in egg volume within a clutch. A significant difference in egg volume was found within six-egg clutches, and the first egg was the smallest. Nestlings that hatched from small eggs early in the hatching order suffered lower mortality rates than nestlings that hatched from large eggs laid late in the hatching order. The duration of time between settlement of a female in a male territory and clutch initiation decreased with date. Intraclutch variation in egg volume may be caused by a trade-off between the time to develop an egg and the volume of the first egg within a clutch. Because eggs that hatch first do not need to be large for the hatchling to survive, the Bull-headed Shrikes may advance the clutch-initiation date at the cost of reducing the volume of the first egg.
  • M Takagi
    JOURNAL OF ETHOLOGY 21 (1) 9 - 14 0289-0771 2003 [Refereed][Not invited]
     
    The difference in the reproductive performance of males and females of the Bull-headed Shrike (Lanius bucephalus) according to age class, i.e. yearling and adult, was studied, and the age-related difference was examined according to parental feeding behavior. The clutch initiation date was not affected by the age class. Females that paired with an adult male laid more eggs per clutch than those paired with a yearling male. The age class of males affected the mass of nestlings at 6 days old, and the age class of females affected the mass of nestlings at 12 days old. The effects of the age of either parent independently were observed at different breeding stages. A change in the degree of nestling feeding peformed by the male and female parents occurred at some point between when the broods were 6 days and 12 days old. It is likely that this caused an effect of age at different stages of the breeding cycle. The effects of the age of the male parent are consistent with accounts of age-related reproduction in raptors where males provide resources to offspring. Individual improvements in foraging skills and/or courtship feeding rate are suggested to be possible explanations.
  • Masaoki Takagi
    Journal of Field Ornithology 74 (1) 45 - 52 0273-8570 2003 [Refereed][Not invited]
     
    Philopatry and habitat selection were examined for migratory populations of the two sympatric shrike species, the Bull-headed (Lanius bucephalus) and Brown (L. cristatus) shrikes in northern Japan between 1992 and 1997. Although 18% of banded Bull-headed Shrike males returned to the previous breeding area, no female did. In Brown Shrikes, 43% and 13% of banded males and females, respectively, returned to the area. Brown Shrikes are significantly more philopatric than Bull-headed Shrikes. Even successful breeders in Bull-headed Shrikes did not always return to the area near their nesting site of the previous year. Successful breeders in Brown Shrikes were faithful to their past breeding site. Brown Shrikes decreased by 67% due to habitat loss over four years, while the population of Bull-headed Shrikes was stable. The degree of philopatry was inconsistent with the population trends of the two shrikes. While Bull-headed Shrikes did not have habitat preferences in the study area, Brown Shrikes bred mainly in natural grasslands with shrubs. Since available habitat for Brown Shrikes has decreased rapidly in and near the study area, the philopatry of Brown Shrikes may result from a scarcity of habitat that inhibits dispersal. Bull-headed Shrikes may have a higher tendency to disperse because they are habitat generalists. With its more narrow requirements, the Brown Shrike appears to have suffered significantly from habitat loss, while the Bull-headed Shrike has not been adversely affected.
  • M Takagi
    ECOLOGICAL RESEARCH 17 (6) 617 - 624 0912-3814 2002/11 [Refereed][Not invited]
     
    I investigated seasonal changes in the relationships between brood size, body mass of nestlings and body mass of parents of the bull-headed shrike, Lanius bucephalus , in Ishikari, northern Japan. When the broods were 12 days old, the body mass of the heaviest nestling in a brood did not differ among brood sizes, or throughout the season. However, the body mass of the lightest nestlings in a brood was different among brood sizes. The body mass of the lightest nestling in five- and six-nestling broods decreased throughout the season. The lightest nestling in four-nestling broods, and the lightest and the second lightest nestlings in five-nestling broods, were significantly lighter than the heaviest nestling in broods of this size. It is likely that pairs with six nestlings at 12 days old can feed at least five of these nestlings enough to ensure their survival . The standardized body mass of parents (SBM), which was defined as the body mass divided by the length of the tarsus, did not differ among brood sizes, or throughout the season. It is possible that the relationship between the constancy of the SBM and the seasonal decline in the body mass of nestlings indicates that bull-headed shrikes have a limit to their parental efforts.
  • M Takagi
    ECOLOGICAL RESEARCH 17 (3) 411 - 414 0912-3814 2002/05 [Refereed][Not invited]
     
    Changes in body mass of both sexes of the bull-headed shrike, Lanius bucephalus , were investigated over the six breeding phases of this species. Standardized body mass (SBM), which was defined as body mass divided by the length of the tarsus, of the males was relatively constant over the phrases, while the SBM of the females changed drastically. In the females, the SBM during egg-laying was higher than the SBM in all the other breeding phases. The SBM of the females did not differ between the incubation and early-nestling phases, and was lowest during the fledgling phase. Mass loss in bull-headed shrikes did not correspond to an adaptive adjustment of body mass to permit a reduction in the power required for flight in the nestling period. It is likely that incubating females constantly maintain their body mass to invest in parental efforts from the incubating to nestling periods.
  • Takagi Masaoki
    Journal of the Yamashina Institute for Ornithology 山階鳥類研究所 34 (1) 30 - 38 0044-0183 2002 [Refereed][Not invited]
  • CHOCHI M
    Japan Ornithol. Sci. 1 163 - 166 2002 [Refereed][Not invited]
  • Hatching pattern and egg volume variation within a clutch in relation to sibling competition.
    TAKAGI Masaoki
    Proceedings of the Japan society for comparative endocrinology_ 17 4 - 5 2002 [Refereed][Not invited]
  • Masaoki Takagi
    Ecological Research 16 (1) 55 - 63 0912-3814 2001/03 [Refereed][Not invited]
  • Masaoki Takagi
    J. Yamashina Inst. Ornithol. Yamashina Institute for Ornitology 32 (1) 13 - 23 0044-0183 2000/05/31 [Refereed][Not invited]
     
    It has been inferred that the population of Bull-headed Shrikes, Lanius bucephalus, increased rapidly on Minami-daito Island, Japan, beginning in 1973-74. This isolated population on a remote island in the Pacific Ocean is about 500km away from the previous southern limit of the breeding area of this species. The plumage and external morphological characteristics of the Minami-daito Bull-headed Shrikes are described, and the results of an investigation into the distribution, sex ratio, and breeding ecology of the population made from January to February and from April to May 1998, are discussed. As there have been previous reports of hybrids between the Bull-headed Shrike and the L. cristatus lucionensis subspecies of the Brown Shrike (a summer migrant to Japan), the characteristics of the Bull-headed Shrikes currently on Minami-daito were compared with those of both L. c. superciliosus and L. c. lucionensis. The Minami-daito Bull-headed Shrikes were found not to show either plumage or external morphological characteristics typical of L. c. lucionensis. Shrikes were observed in all of the typical habitats on the island, at a rate of 2.1 males per km and 1.6 females per km. Most nests were built in Calophyllum inophyllum, and the mean nest height above ground was 252cm. Egg laying was observed for the first time in late January, and continued until April. It was not possible to determine whether or not shrikes continued to lay after May.
  • TAKAGI Masaoki, HIGUCHI Hiroyoshi
    Japanese Journal of Ornithology 日本鳥学会 49 (3) 113 - 117 0913-400X 2000 [Refereed][Not invited]
     
    Habitat selection by Ijima's Willow Warblers Phylloscopus ijimae was studied on Miyake-jima (Miyake Island) in the Izu Islands, in the western Pacific Ocean. In order to investigate the relationship between the density of warblers and landscape, we selected three study sites in different landscapes, and compared the density of warblers among them. Forest type did not influence warbler density. The lowest density of warblers was recorded at the site that was heavily fragmented by agricultural fields. Warbler habitat was analysed at a fine scale (50 m x 50 m quadrats), and a stepwise multiple regression analysis was employed to analyse the relationship between warbler density and the vegetation characters. Three factors, tall tree cover, forest edge length, and forest type were adopted as explanatory variables by the analysis. At the fine scale, well-developed continuous laurel forests have the greatest carrying capacity density of for Ijima's Willow Warblers. The results of this study show that Ijima's Willow Warblers are particularly associated with welldeveloped continuous forests, and that laurel forest provides more suitable habitat for them than does deciduous forest.
  • M Takagi
    IBIS 141 (1) 140 - 141 0019-1019 1999/01 [Refereed][Not invited]
  • TAKAGI Masaoki
    Jpn. J. Ornithol. 日本鳥学会 48 (1) 61 - 81 0913-400X 1999 [Refereed][Not invited]
     
    It has been widely suggested that inbreeding causes a loss of constitutional vigour and fertility in domestic livestock.Long-term field studies of pedigrees in avian populations have also revealed that inbreeding typically decreases the fitness of each individual, but may increase fitness under certain circumstances. The degree of inbreeding in a population depends on its geographical isolation and/or its demographic situation.Under the restricting condition of dispersal of individuals, inbreeding may be more adaptive than out-breeding. The recent introduction of DNA analysis to the field of avian ecology has facilitated research into degrees of inbreeding. It is now possible to strictly assess the relationship between inbreeding and fitness. A decrease in heterozygosity has actually corresponded with the deleterious effects of inbreeding in wild avian populations. For such studies it is essential that we obtain demographic parameters, genetic data, and the parameters of life history traits.To that end it is necessary to introduce populations, or to locate populations of which the year of foundation is known.
  • TAKAGI Masaoki, UEDA Masako
    Japanese Journal of Ornithology 日本鳥学会 46 (3) 175 - 176 0913-400X 1998/02 [Refereed][Not invited]
     
    岩棚だけにしか営巣しないと思われていたオガサワラノスリ Buteo buteo toyoshimai が,1997年3月から5月にかけて小笠原諸島父島清瀬地区において,人為移入高木種のモクマオウ Casuarina equisetifolia に営巣した.また,島民からの聞き取り調査で1950年代の後半にも同様に移入種のリュウキュウマツ Pinus luchuensis に営巣した記録があることが明らかになった.
  • Takagi Masaoki, Takahashi Mitsuhiko
    Strix 財団法人日本野鳥の会研究センター 15 (15) 127 - 129 0910-6901 1997 [Refereed][Not invited]
  • TAKAGI Masaoki, ABE Shiori
    Japanese journal of ornithology 日本鳥学会 45 (3) 167 - 174 0913-400X 1996/12 [Refereed][Not invited]
  • Takagi Masaoki, ABE Shiori
    Journal of the Yamashina Institute for Ornithology Yamashina Institute for Ornitology 28 (2) 103 - 105 0044-0183 1996/10 [Refereed][Not invited]
     
    性的二型が不明瞭なアカモズの羽色の1形質に性的な差異を認あたので報告する。著者はアカモズの額の白色帯を計測し,雌雄で比較を行った。その結果,雄(平均6.5mm)は雌(3.5mm)に比較して有意に広い結果が得られ,額の白色帯は雌雄の識別に有効な指標の1つとなることを示唆した。
  • TAKAGI Masaoki
    Japanese Journal of Ornithology 日本鳥学会 45 (3) 187 - 190 0913-400X 1996 [Refereed][Not invited]
     
    アカモズは羽色の性的二型が不明瞭なので,形態計測値の雌雄比較,および判別分析による雌雄判別を試みた.調査は1992～1996年の5～7月に北海道石狩郡で行なった.抱卵斑の有無によって性判別をしたアカモズの雄19個体,雌16個体について,10箇所の外部形態の計測,および体重測定を行なった.その結果,尾長と額の白色帯の幅は雄で有意に長い傾向が認められたが,自然翼長,ふしょ長,露出嘴峰長,嘴高長,嘴幅長,口角長,全頭長には有意な雌雄差は認められなかった。
    計測値間で高い相関関係が認められなかった6変数,すなわち尾長,ふしょ長,露出嘴峰長,嘴高長,嘴幅長,額の白色帯の幅を説明変数として,変数増加式の多変量線形判別分析を行なった.その結果,尾長と額の白色帯の幅の2変数が選択され,以下の判別式が得られた.
    Z=23.8-0.66x1+0.24x2(F=40.28, dfs=2.29, P<0.0001)
    x1は尾長(mm), x2は白色帯の幅(mm)を示し,判別値Z<0で雄, Z>0で雌として判別される.この判別式を用いたときの雄の判別率は89.5%,雌の判別率は100%,両性では94.3%であり,雌雄の判別がほぼ可能であることがわかった.繁殖地に渡来したばかりの雌は抱卵斑を発達させていないので,その時期の雌雄の識別にこの判別式は効果的である.
  • M Takagi, M Ueta, S Ikeda
    JOURNAL OF RAPTOR RESEARCH 29 (4) 267 - 269 0892-1016 1995/12 [Refereed][Not invited]
  • TAKAGI M
    Proceeding Western Foundation Vertebrate Zoology 6 200 - 2003 1995 [Refereed][Not invited]
  • 高木昌興, 樋口広芳, 伊豆諸島三宅島におけるアカコッコ, Turdus celaenops, の環境選好とイタチ放獣の影響, Strix
    Strix 11 47 - 57 1992 [Refereed][Not invited]

MISC

Books etc

Presentations

Association Memberships

  • 日本鳥学会   日本生態学会   

Research Projects

  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2024/04 -2027/03 
    Author : 高木 昌興, 高久 元, 加藤 徹
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2020/07 -2023/03 
    Author : 高木 昌興, 安藤 温子
     
    南大東島で2-8月まで198巣をモニタリングし、106巣で産卵を確認、86巣で少なくとも1個体の雛が巣立った。繁殖の失敗は、繁殖個体の消失や原因不明の放棄、人為的に移入されたネコやイタチよる雛の捕食である。雛の捕食対策は施しているが不測の事態に遭遇した。北大東島への再導入では、この経験をもとに対策を行う。モニタリング調査を行っている巣で繁殖した親個体のすべてを捕獲し、形態計測、色足輪での標識、採血、遺伝解析を行った。育雛中の8つがいの雌雄にGPSデータロガーを装着した。本種は樹林性の種とされるが、樹林地、畑、並木、民家など様々な環境を利用した。環境の利用様式にも個体差があり、幅の狭い並木沿いに広く行動するつがい、反対に孤立した小面積の樹林地だけで行動するつがいなどが認められた。結果的に行動圏の面積は1.7-32.8haと個体差が大きくなった。行動圏利用の融通性が大きさが、亜種ダイトウコノハズクを樹林が狭く畑が優占する環境で個体群を維持させる要因と考えられる。雛数や給餌頻度は行動圏の面積と関係していなかった。行動圏の面積や形は周囲の個体との関係や餌動物の生産性と関係する。再導入後、繁殖つがい数が少ない段階ではつがい間に干渉は生じないであろう。また雌の行動圏は雄よりも広く、餌を集め育雛を分担し、雄は狭くなわばり防衛の役割を果たした。前年までに足輪をつけた個体を徹底的に探索し、両親が判明している82個体の雄を含め、435個体の雄の鳴き声を録音した。時間周波数解析を行い、形質値の親子回帰分析とランダムに親子を組み合わせる解析により、雄の鳴き声は遺伝形質と示唆された。南大東島では異なる遺伝的形質を持った雌雄が配偶することが判明しており、雌は配偶者相手の鳴き声を避けることで近親交配を回避する可能性が示唆される。なお本年も北大東島には亜種ダイトウコノハズクが生息していないことを確認した。
  • 衛星追跡で解明する生得的なさえずりを持つ鳥類アカショウビンの生態的種分化
    KAKEN：緒戦的萌芽研究
    Date (from‐to) : 2016 -2018 
    Author : 高木 昌興
  • 人為的環境改変によるリュウキュウコノハズク二系統の同所化と浸透性交雑に関する研究
    KAKEN 基盤研究B：
    Date (from‐to) : 2016 -2016 
    Author : 高木 昌興
  • 非学習形質であるフクロウ類の鳴き声の地理的分布は遺伝構造を反映するか？
    KAKEN：基盤研究C
    Date (from‐to) : 2012 -2014 
    Author : 高木 昌興
  • 南半球における托卵性鳥類と宿主の軍拡競争の新展開：温帯ドグマからの脱却
    KAKEN：基盤研究A
    Date (from‐to) : 2011 -2014 
    Author : 上田 恵介
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2009 -2011 
    Author : UEDA Keisuke, HIROWATARI Toshiya, YOSHIYASU Hiroshi, TAKAGI Masaoki
     
    Lepidoptera fauna of five owl species nests was investigated in Japan. Seventeen moth species were identified : Niditinea striolella(Tineidae), Agonopterix sp.(Elachistidae) from Ketupa blakistoni nests ; Monopis longella(=pavlovskii), M. flavidorsalis, M. sp. M. congestella, Niditinea baryspilas, N. striolella, Tineidae sp.(Tineidae), Martyringa ussuriella(Oecophoridae), Mabra charonialis(Crambidae), Pyralis regalis(Pyralidae) from Strix uralensis nests ; Tinea translucens, Niditinea baryspilas(Tineidae) from Ninox scutulata nests ; Opogona sacchari, O. sp. Phaeoses sp. from Otus lempiji nests ; Opogona sacchari, Phaeoses sp., Setomorpha sp.(Tineidae), Endotricha theonalis(Pyralidae) from Otus elegans nests. The role as ecosystem engineers of owls and the relationships between moths and owls were discussed.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2009 -2011 
    Author : TAKAGI Masaoki
     
    Fledgling male Daito Scops Owls settled in vacant sites near each nest as soon as possible they can after fledging, and fledgling females leisurely settled far away from than their nests. Genetic analyses uncovered that pair formation occurred between unrelated individuals, and extra-pair fertilizations occurred in the population. Heterozygosities in owlets by extra-pair fertilization were higher than by pair fertilization. Females chose genetically dissimilar males as their social mates, and in addition married females accepted copulation with genetically more dissimilar males. It was also suggested that males could recognize the differences in hoot calls. The similarity of hoots between a social father and his son, and the dissimilarity of hoots between a social father of females and the married male are verifying by pedigree analyses of hoots.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2009 -2011 
    Author : NISHIUMI Isao, YAMASAKI Takeshi, HAMAO Shoji, SEKI Shin-ichi, TAKAGI Masaoki, IWAMI Yasuko, SAITOH Takema, MIZUTA Taku
     
    Researches on speciation and species classification of allopatric populations of 14 land bird taxa(19 species) were conducted through DNA analyses, morphological analyses and ecological analyses including vocal analysis of songs. As the results, extremely various patterns of the population structure and speciation of land birds in and around the Japanese Archipelago were found. That is to say, molecular analyses suggested that the population structures of land bird species discord with the geological history of the Ryukyu Islands, and extremely various patterns of population differentiations at every species are found. Locations of geographical boundary line are various in each species as well as the degree of genetic differentiation and the age of population division. Furthermore, the degree of morphological division and ecological division are also various and they are not concordant with that of genetic division all time. Evolution of songs may be influenced from coexistence or not of the related species, namely it is 'character displacement' of songs. Morphological adaptive evolution may be accelerated from the adaptive behavior to artificial environmental change, cultivation of nearly whole an islet. We suggested the need of reinvestigation to revision of subspecies in several species, e. g. Ryukyu Scops Owl Otus elegans and Narcissus Flycatcher Ficedula narcissina, and even to revision of species in some species, e. g. Taczanowski's Grasshopper Warbler Locustella pleskei and Brown-eared Bulbul Hypsipetes amaurotis. We have finished revision of species and subspecies only in Arctic Warbler Phylloscopus borealis and White's Thrush Zoothera dauma in the period of this research project, thus the other revisions remain to future studies.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2006 -2009 
    Author : UEDA Keisuke, EGUCHI Kazuhiro, BISHIUMI Isao, TAKAGI Masaoki, TAKASU Fugo, HAMAO Shoji
     
    A new anti-parasitism behaviour was observed in the Large-billed Gerygone Gerygone magnirostris and the Mangrove Gerygone G. laevigaster which are hosts of the Little Bronze-cuckoo Chalcites (formally Chrysococcyx) minutillus. This behaviour, termed parasite nestling ejection, involves the physical removal of live parasite nestlings from active nests and represents a type of chick discrimination. The discovery of parasite nestling ejection by Gerygones represented a significant finding for anti-parasitic behaviour research at the nestling stage. Although the Little Bronze-cuckoo seemed to start parasitism to Large-billed Gerygone historically, then they seemed to explore the Mangrove Gerygone as a new host.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2005 -2008 
    Author : EGUGHI Kazuhiro, UEDA Keisuke, TAKAGI Masaoki, NISHIUMI Isao
     
    協同繁殖種ハイガシラゴウシュウマルハシにおける手伝い行動の適応的意義が雌雄により異なることを明らかにした. 本種は絶対的協同繁殖種であるが, 巣での手伝い行動は繁殖成功の向上をもたらさなかった. 手伝いへの貢献度はオスではメスよりやや低く, ヒナとの血縁度は給餌貢献に影響しなかったが, メスでは, ヒナとの血縁が遠いヘルパーほど貢献度が高かった. この貢献度の性差は,繁殖地位獲得における性差に基づく.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2005 -2007 
    Author : 高木 昌興
     
    平成19年度は,前年度までと同様に野外調査として,南大東島で繁殖するモズを捕獲,計測,採血,繁殖状況の追跡を行った。室内実験として,CHD遺伝子を用いたヒナの性判別,およびマイクロサテライトDNAを用いた親子判定,つがい間の血縁度の算出を行った。巣内雛の性比を体重の順位にしたがって解析した結果,雄雛の割合で表す性比は,0.47-1.57までの変異が認められた。巣内で最も軽い雛が雌に偏る可能性があったが,さらに標本数を増加させて検討する必要がある。父性の判定の結果,南大東島のモズ個体群では,つがい外受精が生じていることがわかった。つがい外受精は,合計62巣中10巣で確認され,その頻度は16%となった。鳥類におけるつがいが受精の確率は5%未満のことが多く,南大東島のつがいが受精率は比較的高い。また,雛レベルでのつがい外受精率は8%で全253巣中21個体が,社会的つがい以外の雄によって受精されたものであった。このような比較的高いつがい外受精率は,南大東島のような隔離された海洋島の特徴であろう。同時進行したダイトウコノハズクの研究は,つがい外受精でできた仔のヘテロ接合度は,つがいの受精による仔よりも高いことがわかった。隔離された狭い血縁個体が多くなる環境下では,つがい外交尾(受精)が適応的な行動と推察された。このためモズも比較的高いっがい外受精率を示したものと思われる。また,他地域におけるモズの孵化率は90%以上が通常であるが,南大東島では60%と極めて低く,個体間でも大きくばらついた。南大東島のモズの遺伝構造は単純で,対立遺伝子数が少なくつがいが血縁個体なった結果と結論された。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2002 -2004 
    Author : EGUCHI Kazuhiro, UEDA Keisuke, NAGATA Hfisasii, TAKAGI Masaoki
     
    1.During the 3-year study period, we found 14-22 groups of the Grey-crowned Babbler and conducted observations : Mean group sizes were 4.21,3.85 and 4.59 respectively : most groups comprising single monogamous pairs with 1-7 auxiliary birds. Sex ratio was almost unity for groups in which all members were successfully sexed for each year : 11:11(six groups), 25:20(13 groups), and 14:12 (nine groups), respectively. Clutch size was 1-4 eggs (two was commonest) and joint-nesting was observed. Major cause of failure was predation but brood reduction due to starvation was rare. Pairs without helpers could not fledge offspring at all. However, for groups with helpers, there was no significant correlation between the number of fledglings and that of helpers. Almost all members of groups provisioned chicks, while there were a few birds giving no help at all. Birds of one-year old provisioned less than those of two-year old or older. Total provision rate was higher in the larger group than the smaller groups, but the difference was not significant. This species could be an obligate cooperative breeder, but the number of helpers did not influence the reproductive success remarkably. 2.During the 3-year study period, 29 broods (45 nestlings) in total were sexed with the DNA sexing method. Sex ratio of nestlings was male biased : 30 (66.7%) were males and 15 (33.3%) were females. Almost all broods with more than one chick were occupied by either sex. For groups with female-biased helper sex ratio, the sex ratio of broods was male-biased, and vice versa. It is likely that female parents of the Grey-crowned Babbler adjust the sex ratio of a brood according to the sex ratio of helpers and the number of helpers weighted by the age of helpers. 3.We obtained the evidence about the cooperative breeding in the population of the Red-backed Fairy-wren in the tropic monsoon area. In 2004, five of 17 groups observed accompanied with one or more auxiliary birds (helpers). Total provisioning rate for chicks was higher in the groups with helpers than in the groups without helpers. Although both sexes became helpers, males outnumbered females. All dominant males had black and red plumage, while helper males (=subordinates) had female-like dull plumage.
  • Avian Ecology
  • Inbreeding in Wild Arian Poplulation
  • Evolution of Arian Life History traits

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