Predation on Endangered Species by Cats in the Northern Forests of Okinawa-Jima Island, Japan

Okinawa-jima Island is a part of the Ryukyu Archipelago, Japan and some endemic animals occur. Many of the native animals are limited to the northern part of this island. Here, we examined the predation effect by domestic cats on native species in the northern part of the island. Route surveys were conducted from September 2017 to February 2018, and cats were captured from 2013 to 2018. In total 60 scats (36 by route surveys and 24 from seven captured cats) were collected. At least 16 animal species were found in domestic cats' scats. Traces of endemic Okinawa spiny rats (Tokudaia muenninki) were the most frequently found from scats collected by route surveys (61.1% in total; 71.4% in the core route, set around the distribution area of Okinawa spiny rats), followed by Ryukyu long-furred rats (Diplothrix legata) (16.7% in total; 21.4% in the core route). Our results showed that domestic cats might exert a significant predation pressure on native endemic vertebrates, especially on Okinawa spiny rats.