Relative importance of landscape features, stand structural attributes, and fruit availability on fruit-eating birds in Japanese forests fragmented by coniferous plantations

Abstract Replacement of natural forests with plantations is causing forest loss and fragmentation worldwide. There is a great need for conservation and restoration of fauna in these fragmented forests, particularly those with special ecological functions, such as fruit-eating birds. In this 3-year study, we explored the relative importance of landscape-level and local factors for the richness and abundance of fruit-eating birds in broad-leaved forest patches scattered within a coniferous plantation in Japan. As local factors of remnant forests we included fleshy fruit availability and stand structural attributes, and then analyzed how the relative importance of these factor varies between the breeding (May–August) and non-breeding (September–December) seasons and among three bird size classes. Our results provide new insights into seasonal variations in the factors associated with bird richness and abundance and demonstrate the importance of fruit availability in the remnant forest patches. The main factors showing positive associations with bird richness/abundance were stand structural attributes (e.g., tree basal area) and landscape variables (e.g., proportion of broad-leaved forest) during the breeding season, whereas it was fruit availability during the non-breeding season, when migrating birds are dominant. We detected only minor variations in the associated factors among the three size classes. Thus, preserving continuous mature forests is of great importance for conserving breeding communities of fruit-eating birds, and maintaining fruit availability is an effective approach for supporting migrating birds during the non-breeding season. These findings are applicable to forest management aimed toward biodiversity conservation in regions being replaced or to be replaced by plantations, such as in many areas of temperate East Asia.