Japanese Journal of Ornithology
Online ISSN : 1881-9710
Print ISSN : 0913-400X
ISSN-L : 0913-400X
SHORT NOTE
Establishment of, and long-term changes in, Great Cormorant colonies in Aomori Prefecture
Rina HONDASeiichi ABEMasao TAKAHASHINobuyuki AZUMA
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2022 Volume 71 Issue 1 Pages 21-28

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Abstract

Long-term monitoring of a long-established Great Cormorant colony was conducted during 1980–2020 and a large-scale census of cormorant colony distribution during 2015–2020 was conducted in Aomori Prefecture, north Japan. This research has revealed relationships between fluctuating nest numbers and the timing of new colony establishment. The long-standing colony experienced increases in nest numbers. The size of colony decreased a year or two after reaching maximum size, then recovered. These cycles were repeated four times during the study period. New colony establishment followed nest decrement at the main colony during 2009–2011, and 10 new colonies had been founded by 2020. This indicates that nest decrement and natural dispersal of breeding individuals from the main colony were the likely triggers for the establishment of new colonies.

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© 2022 The Ornithological Society of Japan
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