Abstract
<jats:p>Tree cavities are essential nesting and resting sites for many arboreal rodents, and clarifying seasonal changes in tree cavity usage and cavity selectivity is important for understanding their life history. In this study, we aim to clarify the nest-box selection by the island endemic Ryukyu long-furred rat (<i>Diplothrix legata</i> Thomas) for nesting and daytime resting sites, with the objective of determining seasonal changes in nest-box usage and the nest-building period. From March 2022 to February 2026, 83 nest boxes were established in the subtropical forests in the northern part of Okinawajima Island, Japan. In addition, camera trap surveys were conducted at 24 of the 83 nest boxes. As a result, this species significantly selected nest boxes located at high positions (4.4 ± 1.1 m) as nesting sites, but the nest box height was not chosen as resting sites. These differences in nest-box selection based on usage may be related to predation avoidance strategies in this study area, where native snakes are the top predators, and to the low predation pressure resulting from the absence of carnivores. Nest building occurs primarily during the first half of the breeding season: nest-box usage by mature adults was significantly higher during the breeding season than the non-breeding season, and group use was recorded from November to March. Additionally, nest boxes were sometimes used as resting sites when typhoons approached. The seasonal variations in nest-box use are thought to reflect the life history of this species on this small island.</jats:p>