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Marine Ecology Progress Series

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MEPS 466:249-259 (2012)  -  DOI:

Spatio-temporal responses of black-tailed gulls to natural and anthropogenic food resources

Ken Yoda1,*, Naoki Tomita2,4, Yuichi Mizutani1, Akira Narita3, Yasuaki Niizuma2

1Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
2Faculty of Agriculture, Meijo University, 1-501 Shiogamaguchi, Tenpaku-ku, Nagoya 468-9502, Japan
3Aomori Prefectural School for the Deaf, 125-1 Aza-Inamori, Yasuda, Aomori 038-0021, Japan
4Present address: Division of Avian Conservation, Yamashina Institute for Ornithology, 115 Konoyama, Abiko City, Chiba 270-1145, Japan

ABSTRACT: Urbanization affects animal movements. However, how urban omnivores respond to natural and human-related food sources with different spatio-temporal structures remains poorly understood. Here, we used animal-borne GPS, video data loggers and high-resolution mapping to examine the foraging behaviour of black-tailed gulls Larus crassirostris during their incubation and hatching period. As expected, the gulls fed not only on natural food at sea (e.g. anchovy and cuttlefish), but also on human-related food sources in 3 kinds of feeding grounds on land, i.e. fishery- or meat-processing plants or markets, private houses and paddy fields. Furthermore, the gulls responded to the different temporal and spatial dynamics of the feeding grounds. The gulls were distributed among these feeding grounds in response to the availability and ephemerality of each food source. Natural-food foraging trips (i.e. ocean) and anthropogenic-food trips (i.e. inland) have different spatial properties, showing a Lévy search of μ = 2 with larger foraging range and patterns closer to ballistic movement with smaller foraging range, respectively. Thus, the gulls responded flexibly to the contrasting food resources of natural and human-related food sources with different temporal and spatial heterogeneities.

KEY WORDS: ■Larus crassirostris · Habitat use · Seabirds · GPS · Video · Data logger · Movement

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Cite this article as: Yoda K, Tomita N, Mizutani Y, Narita A, Niizuma Y (2012) Spatio-temporal responses of black-tailed gulls to natural and anthropogenic food resources. Mar Ecol Prog Ser 466:249-259.

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