title: Effects of an invasive ant on land snails in the Ogasawara Islands.
abstract: We investigated how Pheidole megacephala has affected endemic achatinellid snails because these snails are excellent indicators of the impact of ants and they have high conservation value in Ogasawara. In 2015 we surveyed the Minamizaki area of Hahajima Island of Ogasawara, designated a core zone of the World Heritage Site, for P. megacephala. In Minamizaki, we determined the distribution and density of achatinellid snails in 2015 and compared these data with their distribution and density in 2005. Land cover in the survey area was entirely forest. We also tested whether P. megacephala preyed on achatinellid snails in the laboratory. P. megacephala was present in the forested areas of Minamizaki. Achatinellid snails were absent in 19 of 39 sites where P. megacephala was present, whereas in other areas densities of the snails ranged from 2 to 228 individuals/site. In the laboratory, P. megacephala carried 6 of 7 achatinellid snails and a broken shell was found. Snail distribution and density comparisons and results of the feeding experiments suggest that the presence of P. megacephala has contributed to the decline of achatinellid snails in forests in the survey area. Yet, P. megacephala is not on the official list of invasive non-native species. Stakeholders using the list of invasive species to develop conservation programs should recognize that invasiveness of non-native species differs depending on the ecosystem and that official lists may not be complete.
authors.affiliation: Graduate School of Life Sciences & Center for Northeast Asian Studies, Tohoku University, 41 Kawauchi, Aoba-ku, Sendai, Miyagi, 980-8576, Japan. s.uchida1993@gmail.com.
authors.forename: Shota
authors.initials: S
authors.lastname: Uchida
authors.affiliation: Ogasawara Division of Japan Wildlife Research Center, Okumura, Ogasawara, Tokyo, 100-2101, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Mori
authors.affiliation: Hahajima Branch of Ogasawara Ranger Office, The Ministry of the Environment, Shizukazawa, Hahajima, Ogasawara, Tokyo, 100-2211, Japan.
authors.forename: Tsubasa
authors.initials: T
authors.lastname: Kojima
authors.affiliation: Ogasawara Environmental Planning Laboratory, Motochi, Hahajima, Ogasawara, Tokyo, 100-2211, Japan.
authors.forename: Kayo
authors.initials: K
authors.lastname: Hayama
authors.affiliation: Ogasawara Environmental Planning Laboratory, Motochi, Hahajima, Ogasawara, Tokyo, 100-2211, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Sakairi
authors.affiliation: Graduate School of Life Sciences & Center for Northeast Asian Studies, Tohoku University, 41 Kawauchi, Aoba-ku, Sendai, Miyagi, 980-8576, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Chiba
mesh_terms: D000818:Animals; D001000:Ants; D003247:Conservation of Natural Resources; D058865:Introduced Species; D062312:Islands; D011157:Population Dynamics; D012908:Snails
keywords: Hahajima Island; Isla Hahajima; Sitio UNESCO de Patrimonio Mundial; UNESCO World Heritage Site; achatinellidae; dispersión pasiva; especie introducida; introduced species; isla oceánica; oceanic island; passive dispersal