沿岸と内陸におけるカワウの産卵開始時期とその同調度合い  [in Japanese] The timing and synchronization of egg-laying in Great Cormorants breeding in coastal and inland colonies  [in Japanese]

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Author(s)

    • 井上 裕紀子 INOUE Yukiko
    • 国際水産資源研究所かつお・まぐろ資源部混獲生物グループ National Research Institute of Far Seas Fisheries, Tuna and Skipjack Resources Division, Ecologically Related Species Group
    • 土屋 健児 TSUCHIYA Kenji
    • 名城大学農学部環境動物学研究室 Laboratory of Environmental Zoology, Faculty of Agriculture, Meijo University
    • 新妻 靖章 NIIZUMA Yasuaki
    • 名城大学農学部環境動物学研究室 Laboratory of Environmental Zoology, Faculty of Agriculture, Meijo University

Abstract

カワウ<i>Phalacrocorax carbo</i>は北海道から九州まで様々な環境(沿岸と内陸)で繁殖し,多様な魚種を採食する.産卵開始時期と一腹卵数に影響する要因を調べるため,中部地域の4~6カ所のカワウコロニーで,繁殖生態を2~3年間調べた.平均産卵日はコロニーや年によって2ヶ月の差があった.内陸のコロニーでは,1週間のうちに全体の20%以上の個体が繁殖を始めることはほとんどなく,同調度が低い一方で,沿岸のコロニーのほとんどが,1~2週間のうちに全体の20%以上の個体が繁殖を始めており,40%以上の個体が繁殖を始めることもあるなど,同調する傾向が認められた.産卵開始時期は気象に影響されなかった.また,一腹卵数は,年,地域に影響を受けなかった.各コロニーにおける産卵開始時期とその同調度合いは,コロニー周辺の餌環境に影響を受けている可能性がある.

Great Cormorants <i>Phalacrocorax carbo</i> breed along coasts and inland in Japan where they feed on local coastal and freshwater fish. To examine factors affecting their timing of egg-laying and clutch size, their breeding ecology was studied at 4-6 colonies for 2-3 years in Aichi, Gifu and Mie prefectures in central-west Honshu, Japan. The mean date of egg-laying ranged over about two months (from March to May) among colonies and years. In the coastal colonies more than 20% of individuals laid eggs within one or two weeks and more than 40% of birds at most began to breed simultaneously, while such synchronization of egg-laying was rarely observed in inland colonies. The timing of egg-laying was not related to either rainfall or air temperature during winter. Clutch size differed neither between inland and coastal colonies, nor between years. We suggest that differences in food conditions around coastal and inland colonies influenced the degree of synchronization of egg-laying.

Journal

  • Japanese Journal of Ornithology

    Japanese Journal of Ornithology 61(1), 6-16, 2012-04-20

    The Ornithological Society of Japan

References:  52

Cited by:  1

Codes

  • NII Article ID (NAID)
    10031164381
  • NII NACSIS-CAT ID (NCID)
    AN10314294
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    0913400X
  • NDL Article ID
    023770486
  • NDL Call No.
    Z18-866
  • Data Source
    CJP  CJPref  NDL  J-STAGE 
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