DNA Metabarcoding Unveils Habitat-Linked Dietary Variation in Aerial Insectivorous Birds

The conversion of tropical forests into urban and agriculture landscapes may alter insect populations through habitat disturbance and impact the diets of aerial insectivores. Most dietary studies on aerial insectivores have limitation on identifying prey at higher taxonomic levels in broad landscapes, restricting species-level identification and thus making a detailed dietary comparison impossible. This study examines the dietary changes through adaptation of house-farm swiftlets (<i>Aerodramus</i> sp.) and Pacific swallows (<i>Hirundo tahitica</i>) across three distinct habitats in Peninsular Malaysia: mixed-use landscapes, oil palm plantations, and paddy fields. High-throughput DNA metabarcoding with ANML primers targeting mitochondrial <i>CO1</i> gene, identified 245 arthropod prey species, with six dominant orders: Coleoptera, Diptera, Blattodea, Hemiptera, Hymenoptera, and Lepidoptera. Mixed-use landscapes supported the highest dietary diversity and niche breadth, reflecting their ecological complexity. Paddy fields exhibited moderate diversity, while oil palm plantations demonstrated the lowest diversity, influenced by simplified vegetation structures and limited prey availability. The consumption of agricultural pests and vector species highlights the critical ecological role of aerial insectivorous birds in natural pest management and mitigating vector-borne disease risks. This research emphasizes the importance of conserving habitat heterogeneity to sustain the ecological services provided by these birds, benefiting both agricultural productivity and public health.