Habitat Fragmentation Drives Disappearance of Specialised Forest Birds in Tropical Urban Landscapes, While Omnivores Thrive at the Forest Edge

ABSTRACT

Urbanisation leads to the fragmentation of forest patches within tropical landscapes. However, the specific ecological drivers of urban forest fragmentation and their influence on bird assemblages and ecosystem function remain poorly understood. This study examined the effects of habitat fragmentation on bird richness and the abundance of feeding guilds, in relation to stand‐ and landscape‐level variables within a tropical urban–forest mosaic. We compared avian assemblages in four fragmented forest patches with a contiguous tropical rainforest in the Greater Kuala Lumpur region. Birds were surveyed using point count method at 150 sampling locations across the sites. At each location, we measured 15 stand‐level variables and quantified four landscape‐level variables. Hierarchical generalised linear models showed that bird species richness was associated with landscape type, the number of bamboo clusters and shrubs, and sampling season. Fruiting trees, flowering trees and distance to the forest edge were key predictors of frugivorous, insectivorous and omnivorous bird abundance, respectively. Habitat fragmentation and edge‐associated conditions negatively affected forest bird assemblages, particularly forest interior specialists and large‐bodied species, which were largely absent from fragmented patches. In contrast, omnivorous species exhibited greater tolerance to edge effects. Although contiguous forests supported substantially higher species richness, fragmented forest patches retained broadly comparable feeding guild abundances, suggesting that functional structure may persist through species turnover rather than species persistence. Our findings highlight the irreplaceable role of intact forests for biodiversity conservation, while emphasising that targeted habitat interventions, such as protecting native fruiting and flowering trees and maintaining understory complexity, can actively enhance the supplementary conservation value of fragmented patches. Integrating these specific patch‐level management strategies with landscape‐scale planning will better inform effective urban planning and conservation strategies.