Movements and activities of male black-tailed gulls in breeding and sabbatical years

Authors

  • Kentaro Kazama,

    1. Laboratory of Marine Ecology, Graduate school of Fisheries Sciences, Hokkaido Univ., 3-1-1 Minatocho, Hakodate, JP-041-8611 Hokkaido, Japan.
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  • Kazuhiko Hirata,

    1. Laboratory of Marine Ecology, Graduate school of Fisheries Sciences, Hokkaido Univ., 3-1-1 Minatocho, Hakodate, JP-041-8611 Hokkaido, Japan.
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  • Takashi Yamamoto,

    1. Laboratory of Marine Ecology, Graduate school of Fisheries Sciences, Hokkaido Univ., 3-1-1 Minatocho, Hakodate, JP-041-8611 Hokkaido, Japan.
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  • Hiroshi Hashimoto,

    1. Laboratory of Marine Ecology, Graduate school of Fisheries Sciences, Hokkaido Univ., 3-1-1 Minatocho, Hakodate, JP-041-8611 Hokkaido, Japan.
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  • Akinori Takahashi,

    1. Laboratory of Marine Ecology, Graduate school of Fisheries Sciences, Hokkaido Univ., 3-1-1 Minatocho, Hakodate, JP-041-8611 Hokkaido, Japan.
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  • Yasuaki Niizuma,

    1. Laboratory of Marine Ecology, Graduate school of Fisheries Sciences, Hokkaido Univ., 3-1-1 Minatocho, Hakodate, JP-041-8611 Hokkaido, Japan.
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  • Philip N. Trathan,

    1. Laboratory of Marine Ecology, Graduate school of Fisheries Sciences, Hokkaido Univ., 3-1-1 Minatocho, Hakodate, JP-041-8611 Hokkaido, Japan.
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  • Yutaka Watanuki

    1. Laboratory of Marine Ecology, Graduate school of Fisheries Sciences, Hokkaido Univ., 3-1-1 Minatocho, Hakodate, JP-041-8611 Hokkaido, Japan.
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K. Kazama, Laboratory of Marine Ecology, Graduate school of Fisheries Sciences, Hokkaido Univ., 3-1-1 Minatocho, Hakodate, JP-041-8611 Hokkaido, Japan. Present address for KK, Laboratory of Environmental Zoology, Faculty of Agriculture, Meijo Univ., 1-501 Shiogamaguchi, Tenpaku, Nagoya, JP-468-8502 Aichi, Japan. E-mail: kntkzma@gmail.com

Abstract

Long-lived animals sometimes skip one or more breeding seasons; however, little is known about their movements and activities during such ‘sabbatical’ periods. Here we present novel data on year-round movements and activities of two male black-tailed gulls Larus crassirostris during a sabbatical year. We compare the data with those in a year when they bred and with those of two other breeding males. The year-round migration routes of two sabbatical males were consistent with those of the breeding males: they returned to the breeding area but did not visit the colony in the sabbatical year. They landed more frequently on water (a potential index of foraging effort) during the non-breeding autumn and winter prior to the sabbatical year than before breeding. Sabbatical gulls may forage more intensively to recover body condition immediately after breeding.

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