Characteristics of nest materials and cavity formations of the Ryukyu long-furred rat (Diplothrix legata, Muridae) on Northern Okinawajima Island, Japan

Abstract

This study aimed to elucidate the characteristics of branches and tree cavities utilized by the Ryukyu long-furred rat (Diplothrix legata). The species gathers branches and leaves, which it transports to cavities for use as resting and nesting sites. We collected branches and leaves from the cavities used by D. legata, along with data on tree species and cavity sizes in the northern part of Okinawajima Island. The branches most frequently carried by D. legata were from Castanopsis sieboldii. We observed branches with cut traces ranging in length from 50 to 544 mm. Similar branches with cut traces were also found on trees cut by black rats (Rattus rattus) on Chihijima Island and the Ogasawara Islands, but they were smaller than those carried by D. legata. Hence, the characteristics of the branches could serve as identifiers for D. legata. While D. legata predominantly occupies natural cavities, it also utilizes cavities excavated by Okinawa woodpeckers (Dendrocopos noguchii). Cavities used by D. legata are typically located in trees with a diameter-at-breast-height > 28.9 cm, indicating the necessity of mature forests for this species.