title: Major decline in marine and terrestrial animal consumption by brown bears (Ursus arctos).
abstract: Human activities have had the strongest impacts on natural ecosystems since the last glacial period, including the alteration of interspecific relationships such as food webs. In this paper, we present a historical record of major alterations of trophic structure by revealing millennium-scale dietary shifts of brown bears (Ursus arctos) on the Hokkaido islands, Japan, using carbon, nitrogen, and sulfur stable isotope analysis. Dietary analysis of brown bears revealed that salmon consumption by bears in the eastern region of Hokkaido significantly decreased from 19% to 8%. In addition, consumption of terrestrial animals decreased from 56% to 5% in western region, and 64% to 8% in eastern region. These dietary shifts are likely to have occurred in the last approximately 100-200 years, which coincides with the beginning of modernisation in this region. Our results suggest that human activities have caused an alteration in the trophic structure of brown bears in the Hokkaido islands. This alteration includes a major decline in the marine-terrestrial linkage in eastern region, and a loss of indirect-interactions between bears and wolves, because the interactions potentially enhanced deer predation by brown bears.
authors.affiliation: 1] Center for Ecological Research, Kyoto University, 2-509-3 Hirano, 520-2113 Otsu, Shiga, Japan [2] Laboratory of Forest Ecosystem Management, Graduate School of Agriculture, Hokkaido University, Kita 9 jo, Nishi 9, Kitaku, 060-8589 Sapporo, Hokkaido, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Matsubayashi
authors.affiliation: Laboratory of Forest Ecosystem Management, Graduate School of Agriculture, Hokkaido University, Kita 9 jo, Nishi 9, Kitaku, 060-8589 Sapporo, Hokkaido, Japan.
authors.forename: Junko O
authors.initials: JO
authors.lastname: Morimoto
authors.affiliation: 1] Center for Ecological Research, Kyoto University, 2-509-3 Hirano, 520-2113 Otsu, Shiga, Japan [2] Research Institute for Humanity and Nature, 457-4 Motoyama, Kamigamo, Kita-ku, 603-8047 Kyoto, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Tayasu
authors.affiliation: Environmental and Geological Research Department, Hokkaido Research Organization, Kita 19 jo, Nishi 12, Kitaku, 060-0819 Sapporo, Hokkaido, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Mano
authors.affiliation: Salmon and Freshwater Fisheries Research Institute, Hokkaido Research Organization, 3-373 Kita-Kashiwagi, 061-1433 Eniwa, Hokkaido, Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Nakajima
authors.affiliation: Chitose Archaeological Operations Center, Chitose Board of Education, Chitose city, 42-1 Osatsu, 066-0001 Chitose, Hokkaido, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Takahashi
authors.affiliation: Laboratory of Wild Wildlife Management, United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, 3-8-1 Harumi, 183-8538 Fuchu, Tokyo, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Laboratory of Forest Ecosystem Management, Graduate School of Agriculture, Hokkaido University, Kita 9 jo, Nishi 9, Kitaku, 060-8589 Sapporo, Hokkaido, Japan.
authors.forename: Futoshi
authors.initials: F
authors.lastname: Nakamura
mesh_terms: D000818:Animals; D020387:Food Chain; D005843:Geography; D007564:Japan; D015233:Models, Statistical; D001503:Ursidae