Dataset and Code for Manuscript: Understory Bird Species Richness and Limited Spillover from Forest Reserves into Plantations and Orchards in Southeast Asia

This study investigates how different agricultural plantations practices influence understory bird diversity in tropical landscapes in Southeast Asia by comparing monoculture oil palm and rubber tree plantations, polyculture fruit orchards, and nearby forest reserves. Using mist-netting surveys, the study shows that forest reserves support the highest richness and abundance of understory birds and are dominated by forest-specialist species, highlighting their irreplaceable conservation value. Although all agricultural landscapes supported less than half of the forest bird species, polyculture orchards consistently had higher bird richness and more diverse feeding guilds than monoculture plantations, including a small number of forest specialists, suggesting limited biodiversity spillover from forests. In contrast, oil palm and rubber tree plantations were dominated by non-forest specialists, indicating that structurally simplified monocultures act as barriers to forest bird persistence. Among habitat characteristics, understory vegetation cover emerged as the key driver of bird species richness in all landscapes. This study highlights that while agricultural plantations cannot substitute for forests, structurally complex and sustainably managed orchards can partially mitigate biodiversity loss and enhance matrix quality in plantation-dominated tropical landscapes.