The response of bird feeding guilds to forest fragmentation reveals conservation strategies for a critically endangered African eco-region

Abstract

South African coastal forests form part of two critically endangered eco-regions and harbor an extinction debt. Remainingfragments are small, isolated, and embedded within a range of human land-use types. In this study, we ask: how should we investconservation resources if we want to restore this landscape and prevent predicted extinctions? To answer this question, we use pathanalyses to determine the direct and indirect effects of forest area, forest connectivity, and matrix land-use types on species richnesswithin five bird feeding guilds. We found that forest connectivity had a significant direct effect on insectivores—fragments thatwere more connected had more species of insectivores than those that were isolated. Moreover, forest area had a significant indi-rect effect on insectivores that was mediated through tree species richness. Larg er fragments had more species of trees, which ledto more species of insectivores. Fragment area, connectivity, matrix land-use type, and tree species richness had no significanteffects on the species richness of frugivores, nectarivores, granivores, or generalist feeders. To conserve insectivores in coastal for-ests, conservation efforts should focus on maximizing fragment connectivity across the landscape, but also protect the tree commu-nity within fragments from degradation. This can be achieved by including matrix habitats that adjoin forest fragments withinforest conservation and restoration plans. Natural matrix habitats can increase connectivity, provide supplementary resources, bufferfragments from degradation, and could play an important role in safeguarding diversity and preventing extinctions in this threatenedhuman-modified landscape.