title: Ethogram of Immature Green Turtles: Behavioral Strategies for Somatic Growth in Large Marine Herbivores.
abstract: Animals are assumed to obtain/conserve energy effectively to maximise their fitness, which manifests itself in a variety of behavioral strategies. For marine animals, however, these behavioral strategies are generally unknown due to the lack of high-resolution monitoring techniques in marine habitats. As large marine herbivores, immature green turtles do not need to allocate energy to reproduction but are at risk of shark predation, although it is a rare occurrence. They are therefore assumed to select/use feeding and resting sites that maximise their fitness in terms of somatic growth, while avoiding predation. We investigated fine-scale behavioral patterns (feeding, resting and other behaviors), microhabitat use and time spent on each behavior for eight immature green turtles using data loggers including: depth, global positioning system, head acceleration, speed and video sensors. Immature green turtles at Iriomote Island, Japan, spent an average of 4.8 h feeding on seagrass each day, with two peaks, between 5∶00 and 9∶00, and between 17∶00 and 20∶00. This feeding pattern appeared to be restricted by gut capacity, and thus maximised energy acquisition. Meanwhile, most of the remaining time was spent resting at locations close to feeding grounds, which allowed turtles to conserve energy spent travelling and reduced the duration of periods exposed to predation. These behavioral patterns and time allocations allow immature green turtles to effectively obtain/conserve energy for growth, thus maximising their fitness.
authors.affiliation: Graduate School of Informatics, Kyoto University, Sakyo, Kyoto, Japan ; Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, California, United States of America.
authors.forename: Junichi
authors.initials: J
authors.lastname: Okuyama
authors.forename: Kana
authors.initials: K
authors.lastname: Nakajima
authors.forename: Takuji
authors.initials: T
authors.lastname: Noda
authors.forename: Satoko
authors.initials: S
authors.lastname: Kimura
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kamihata
authors.forename: Masato
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Arai
authors.forename: Shiro
authors.initials: S
authors.lastname: Kagawa
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Kawabata
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yamada
mesh_terms: D025041:Animal Migration; D000818:Animals; D059001:Aquatic Organisms / Q000502:physiology; D017753:Ecosystem; D005247:Feeding Behavior / Q000502:physiology*; D060434:Herbivory / Q000502:physiology*; D011235:Predatory Behavior; D014426:Turtles / Q000502:physiology*