FEEDING HABITS OF THE MARINE TOAD, BUFO MARINUS, IN THE BONIN ISLANDS, JAPAN

Abstract

Feeding habits of the marine toad, Bufo marinus, which was introduced to the Bonin Islands (27°N, 142°E), Japan, were investigated by stomach content analysis. The diet composition was expressed in occurrence frequency, number and weight. The frequent prey were ants, Diplopoda, Hemiptera, Armadillidiidae, Lepidoptera larvae and Curculionidae. Prey items which dominated in number were ants, pill-bugs and Diptera larvae. The dominant prey in weight were the giant snail, Achatina fulica, pill-bugs and Diptera larvae. The composition of the marine toad's diet generally reflected the soil macrofauna in the living site. The toad as an opportunistic feeder fed on various kinds of prey living on the soil surface. Large giant snails (larger than 30 mm in shell length) recovered from the toad's stomach mostly lacked shells. These snails were probably eaten after being crushed by man. This fact suggests that toads are able to feed on stationary materials. The stomach content weight tended to become heavier in larger toads. Large toads tended to eat prey larger than 5.0 mm as compared with small ones. Heavy stomach contents generally indicated a higher percentage of animal materials.