Strong predation pressure imposed by an invasive alien predator can induce not only demographic decrease but also rapid adaptive behavioral change of native prey. However, no study has reported adaptive changes caused by invasive mongoose, a globally well-known carnivore that seriously impacts on native fauna on islands. We compared escape behavior among native frogs found in places with different historical impacts of invasive mongoose in Amami Island, southern Japan.

This island harbors no mammalian predator before an introduction of mongooses on 1979, and the introduction caused drastic decline of native frogs. We recorded escape behavior of the frogs using Flight Initiation Distance (FID) in the field, and modeled the escape behavior using generalized least square (GLS) methods to test the effect of potential factors (distance from introduced point of mongoose, distance from the nearest human area, temperature, humidity, body size, distance to refuges).

We found that historical impacts of mongooses induced longer FID of native frogs. This result indicates that historical impacts of an invasive predator can induce rapid adaptive changes in escape behavior of native prey species.