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Factors affecting individual variation in nest-defense intensity in colonially breeding Black-tailed Gulls (Larus crassirostris)

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Title: Factors affecting individual variation in nest-defense intensity in colonially breeding Black-tailed Gulls (Larus crassirostris)
Authors: Kazama, Kentaro Browse this author
Niizuma, Yasuaki Browse this author
Sakamoto, Kentaro Q. Browse this author
Watanuki, Yutaka Browse this author →KAKEN DB
Issue Date: Oct-2011
Publisher: Canadian Science Publishing
Journal Title: Canadian Journal of Zoology
Volume: 89
Issue: 10
Start Page: 938
End Page: 944
Publisher DOI: 10.1139/Z11-063
Abstract: The physiological state of parent birds combined with the value of their clutch may affect the intensity of their nest defense. In colonially breeding birds, nest defense intensity may also be affected by the behavior of neighbors. We investigated individual variation in the intensity of nest defense among colonial Black-tailed Gulls Larus crassirostris in two years. Only 30-40% of males attacked a decoy of an egg predator (crow), and the other males and females rarely attacked. Males attacking the decoy had higher levels of plasma testosterone than males that did not attack. Each male's, but not female's, nest defense intensity was consistent throughout the incubation period and also across years. The intensity was not related to egg-laying date, clutch size, or age of offspring. The intensity was likely to be higher when individuals had one or more neighbors, representing higher nest defense intensity in the year where gulls had larger number of adjacent neighboring nests (5.23 nests), but this trend was not observed in the year where they had smaller number of the neighboring nests (3.73 nests). Thus, in addition to testosterone levels, behavior of neighbors also influences the intensity of nest defense.
Relation: http://www.nrcresearchpress.com/journal/cjz
Type: article (author version)
URI: http://hdl.handle.net/2115/47660
Appears in Collections:水産科学院・水産科学研究院 (Graduate School of Fisheries Sciences / Faculty of Fisheries Sciences) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 綿貫 豊

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