title: Feeding kinematics of freshwater turtles: what advantage do invasive species possess?
abstract: The red-eared slider (Trachemys scripta) is an invasive turtle species that is displacing the populations of native freshwater turtles in many countries. However, the mechanism that makes red-eared sliders superior competitors has been less well studied. In this study, we compare the feeding kinematics of the red-eared slider with those of Reeves' pond turtle (Mauremys reevesii), a turtle native to East Asia, and offer an explanation as to why red-eared sliders are superior in food competition. Reeves' pond turtles sympatric to red-eared sliders have been reported to have a mainly durophagous diet in contrast to the preference for a soft diet in areas of allopatry to red-eared sliders, indicating the dietary shift resulted from food competition. Maximum neck extension and retraction speed are considered to be indicators of striking ability, but were not found to be superior in red-eared sliders. In fact, maximum neck extension speed was significantly higher in Reeves' pond turtles, though this advantage may be counteracted by the longer neck of Reeves' pond turtles, resulting in similar neck extension times. On the other hand, red-eared sliders had a significantly shorter gape cycle time and neck retraction time, indicating that they can complete feeding in a short time. Therefore, red-eared sliders are suggested to be superior in food competition not due to their striking ability, but due to exploiting preferable food in a shorter time.
authors.affiliation: Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan. Electronic address: nishiza@bre.soc.i.kyoto-u.ac.jp.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nishizawa
authors.affiliation: Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Runa
authors.initials: R
authors.lastname: Tabata
authors.affiliation: Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Hori
authors.affiliation: Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Hiromich
authors.initials: H
authors.lastname: Mitamura
authors.affiliation: Field Science Education and Research Center, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Arai
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D005247:Feeding Behavior / Q000502:physiology*; D058865:Introduced Species; D013045:Species Specificity; D013997:Time Factors; D014426:Turtles / Q000033:anatomy & histology / Q000502:physiology*
keywords: Food competition; Red-eared slider; Reeves’ pond turtle; Striking ability