Estimating the life history of invasive frog species Fejervarya kawamurai using body size data.

Fejervarya kawamurai is naturally distributed in the western part of Honshu, Shikoku, Kyushu, and the Ryukyu Islands in Japan. In recent years, the ingression of F. kawamurai has been reported in the Kanto region, and there is concern about the impact of F. kawamurai on the ecosystem. Information on the life history of this invasive species is needed to control this invasive species and to conserve the ecosystems through methods such as eradication and the prevention of population expansion. In the present study, we captured F. kawamurai in paddy fields in Kanagawa Prefecture, and used body size composition method and observed their gonads to attempt to elucidate the life history of this domestic invasive species. The period when F. kawamurai was captured was from first half of April to second half of October, and the breeding season was from first half of May to first half of August. The immature F. kawamurai individuals of both sexes that had finished metamorphosis began to emerge in the first half of July, reaching the body size of mature frogs in August. Immature males matured immediately after overwintering, and immature females matured slightly later, in the first half of May. In addition, the number of mature individuals of both sexes decreased after the first half of July, and none were collected after the second half of August. These results suggest that the surveyed F. kawamurai populations comprised mostly individuals less than one year after metamorphosis. The rapid sexual maturation and alternation of generations of F. kawamurai are considered some of the predominant ecological factors enabling the successful establishment of this frog as a domestic invasive species. [ABSTRACT FROM AUTHOR]