ORNITHOLOGICAL SCIENCE
Online ISSN : 2759-5897
Print ISSN : 1347-0558
9 巻, 2 号
選択された号の論文の9件中1~9を表示しています
ORIGINAL ARTICLES
  • Shinji Yabuta, Hiroko Kawakami, Akira Narita
    原稿種別: Original Article
    2010 年9 巻2 号 p. 109-114
    発行日: 2010/12/25
    公開日: 2010/12/25
    ジャーナル フリー
    Displays of animals do not always elicit equivalent responses from other conspecifics. Considerable variation exists among the responses, but the mechanism causing the variety remains unclear. We investigated how Black-tailed Gulls Larus crassirostris respond to long-call displays of other individuals. Results show that the response varies depending on the context. Territorial birds often respond to the long-calls of non-territorial birds by attacking. However, non-territorial birds typically respond to the long-calls of territorial birds by avoiding them. Nevertheless, they usually respond to the long-calls of their partners by using the same long-call. These results are explained well by the motivational conflict hypothesis.
  • Nozomu J. Sato, Osamu K. Mikami, Keisuke Ueda
    原稿種別: Original Article
    2010 年9 巻2 号 p. 115-121
    発行日: 2010/12/25
    公開日: 2010/12/25
    ジャーナル フリー
    Recent research into the Large-billed Gerygone, a host species of the Little Bronze-Cuckoo, has revealed that the host physically ejects parasitic cuckoo young from its nest, a behaviour not previously observed in any other host-brood parasite system. Curiously, this host does not reject dissimilar foreign eggs despite egg rejection seeming to be a better strategy for it because if successful, there is no risk of the warbler's own eggs being ejected by cuckoo young. In order to explain this puzzle, we present a new hypothesis, termed the egg dilution effect, which argues that parasitic cuckoo eggs serve to ensure host egg survival through the dilution effect and protect against parasitism by multiple females. It is therefore beneficial for hosts to accept cuckoo eggs even if they are capable of discriminating cuckoo eggs from their own. The conditions of this hypothesis, such as small clutch size and high parasitism rate, fit the nature of the host species and thus help explain why this unique anti-parasitic strategy has evolved only in the Large-billed Gerygone.
  • Akira Chiba, Rhyuhei Honma
    原稿種別: Original Article
    2010 年9 巻2 号 p. 123-130
    発行日: 2010/12/25
    公開日: 2010/12/25
    ジャーナル フリー
    In the course of our fieldwork study at Hyo-ko Waterfowl Park, a local preserve in Niigata Prefecture, Japan, we found a male presumed wild hybrid between a Eurasian Wigeon Anas penelope and a Falcated Duck A. falcata in 2007; another or possibly the same individual was found again in 2009. The bird shared morphological traits with both species, although it was biased toward the Falcated Duck. Occasionally, the bird joined courting parties of Eurasian Wigeon, followed Wigeon females or competed with Wigeon males, and also showed courtship displays, e.g. Grunt-whistle, Head-up-tail-up, and Burping call, all of which were more like those of the Falcated Duck than those of the Eurasian Wigeon. Thus, the hybrid bird was sexually active to a considerable extent, but it remains unknown whether or not it actually formed a pair bond with a female of either parent species.
  • Hongshik Oh, Youngho Kim, Namkyu Kim
    原稿種別: Original Article
    2010 年9 巻2 号 p. 131-134
    発行日: 2010/12/25
    公開日: 2010/12/25
    ジャーナル フリー
    We studied the breeding biology of the Japanese Night Heron Gorsachius goisagi from 21 June to 2 August 2009. This species was previously considered an endangered endemic breeding species of southern Japan only, but was found breeding in a valley at the bottom of Mt. Halla at Ara-dong, Jeju City, the southernmost island of Korea. This marks the first record of this species ever to be found breeding in Korea. The forested area consisted predominantly of plants such as Morus bombycis, Cryptomeria japonica, Styrax japonica, Orixa japonica, Viburnum dilatatum, and Lindera erythrocarpa. Materials for the nest were largely M. bombycis, followed by S. japonica, C. japonica, and so forth. There were three eggs in the clutch, and the brooding period lasted for 42 days. A close look into the pellets demonstrated that their main prey items were earthworms, snails, and cicadas. The results of this study represent valuable data, allowing for the mapping out of new methods for managing Gorsachius goisagis, a species currently on the brink of extinction.
  • Pei-Yin Lee, Lih-Jih Wang, Huang-Che Hsu, Lien-Siang Chou, Chao-Chieh ...
    原稿種別: Original Article
    2010 年9 巻2 号 p. 135-140
    発行日: 2010/12/25
    公開日: 2010/12/25
    ジャーナル フリー
    This study compared microhabitat characteristics among nesting, foraging, and singing sites of the Gray-cheeked Fulvetta Alcippe morrisonia in the Fushan Experimental Forest, northeastern Taiwan. Habitat variables, including height above ground, vegetation level, vegetation density at locations where these three types of behavior occurred, and structure, height and diameter at breast height (dbh) of the plant used were recorded from March to July of 2002. The Gray-cheeked Fulvetta predominantly nested in bushes and among herbs (86.7%), but usually foraged and sang in trees (70.8% and 78.3%, respectively). Consequently, significant differences were found in the structure of plants and vegetation level used among nesting, foraging, and singing behavior. Gray-cheeked Fulvettas built their nests at an average height of 1.05 m; however, they foraged around 3.75 m and sang at 5.30 m above ground. On the other hand, nests were situated within the most concealed area, with an average vegetation density of 74%, significantly greater than those of the foraging and singing sites (45%, 38%, respectively). The differential use of microhabitat among these three types of behavior strongly exhibits the divergent adaptation of different behaviors to a bird's environment. This is the first report on habitat selection of various behaviors of the Gray-cheeked Fulvetta, and will contribute to our understanding of the species' dominant role in most lowland forests in Taiwan.
  • Masaru Hasegawa, Emi Arai, Mamoru Watanabe, Masahiko Nakamura
    原稿種別: Original Article
    2010 年9 巻2 号 p. 141-148
    発行日: 2010/12/25
    公開日: 2010/12/25
    ジャーナル フリー
    The maintenance of multiple ornaments by animals can be explained when those multiple ornaments are sexually selected. However, there have been only a few studies of sexual selection on multiple ornaments. We investigated sexual selection on two ornaments, plumage coloration and white spots in the tail, in a population of Barn Swallows Hirundo rustica gutturalis in Japan. There was sexual dimorphism in throat coloration and in the size of the white spots in the tail. Males with a less saturated (colourful) throat and larger white spots in the tail bred earlier than others, indicating a mating advantage for these males. These trends are what would be expected if these ornaments were indeed sexually selected.
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