Eradication programs of alien predators have been conducted on many oceanic islands. However, previous reports showed that densities of native species did not always recover, or even decreased after the eradication. Therefore, monitoring native faunas is important for evaluating effectiveness of eradication programs.

The introduced mongoose (Herpestes auropunctatus), which was introduced to Amami-Oshima island in 1979, has imposed severe impacts on endemic species and subspecies on this island through predation. To protect endemic organisms, the mongoose eradication program began in 2000, and now, the density of mongooses becomes low. Here, we report recovery processes of four endemics (Amami rabbit, Amami tip-nosed frog, Otton frog, and Ishikawa’s frog) using spatial and temporal gradients of mongoose density.

The results showed that all endemics examined increased their population sizes, and three endemics expanded their distribution ranges. However, their recovery rates varied largely among species and places. To explain these differences, we further analyzed effects of land use on recovery rates and densities of endemics.