Abundant and morphologically large birds underpin top-down control in rewired trophic networks of restored forests

Forest restoration is rapidly transforming landscapes worldwide and is expected to restore associated ecosystem services. However, the complex trophic interactions that underpin forest ecosystem integrity remain poorly understood, especially where the reconfiguration or loss of core predators can trigger cascading top-down effects, despite increasing emphasis on process-based conservation. Using faecal DNA metabarcoding of 494 samples from 44 bird species, we reconstructed 2282 unique bird–arthropod trophic interactions. We compared network structure among plantations, secondary and primary forests, partitioned network dissimilarity into interaction rewiring and species turnover relative to primary forests, tested how species characteristics and rewiring probability shape species' role reconfiguration, and evaluated the functional robustness of avian top-down control under characteristic-driven extinctions. Plantations exhibited higher connectance than secondary forests, whereas nestedness and modularity did not differ among forest types. The network dissimilarity was primarily driven by interaction rewiring, which reshaped the network structure by lowering the connectance in plantations but increasing the modularity in secondary forests. Species' roles were differentially reconfigured between restored forests through contrasting mechanisms, with the effects of abundance dominating in plantations, whereas abundance together with the rewiring probability of morphologically large birds shaped core roles in secondary forests. The functional robustness of bird top-down control on herbivorous insects was especially fragile to the simulated loss of abundant species in plantations, while the loss of morphologically large birds consistently weakened the robustness across all forest types. Synthesis and applications: As restoration increasingly reshapes terrestrial food webs, our findings highlight the importance of incorporating trophic roles that underpin avian ecosystem services such as top-down control. Although forest restoration can rebuild trophic network structure, different restoration strategies reconfigure species' roles through distinct characteristic-driven mechanisms, with asymmetric functional consequences. Restoration success should therefore be enhanced by emphasizing the protection of abundant and large birds, while prioritizing mixed vegetation structure and well-connected forest patches to promote the persistence or recolonization of functionally important avian predators.