Dispersal‐limited birds at high risk from cattle farming deforestation in tropical forests

Deforestation driven by farming is a major threat to tropical biodiversity. Although this impact is well documented, assessments at local or regional scales often underestimate biodiversity loss at broader national scales by up to 60%. A key question remains: how do farming activities affect functional diversity and species traits across different spatial scales? We use a large field-based dataset spanning 13 biogeographic regions across Colombia to assess the impacts of forest loss driven by cattle farming, one of the dominant forms of agriculture, on avian functional diversity. Using multispecies occupancy models and established morphological functional trait databases, we quantify changes in functional diversity resulting from forest-to-pasture conversion and identify the most impacted functional dimension. Our results indicate that functional diversity metrics are only slightly affected across ecoregions and largely reflect the national scale of loss, driven by a moderate reduction in functional richness across scales. This suggests a high degree of functional redundancy and resilience within communities, likely due to their high species richness. When examining specific morphological traits, forest conversion leads to a substantial decline in the occupancy probability of dispersal-limited species. While high biodiversity buffers against immediate functional collapse, the decline of dispersal-limited species highlights long-term risks to ecosystem resilience and functional homogenisation. Our findings underscore the importance of trait-based approaches, since aggregate functional diversity metrics may obscure critical impacts. Preserving structural connectivity and protecting large native forest blocks are essential for maintaining functional diversity and dispersal-limited birds, while promoting sustainable agricultural practices can help balance biodiversity conservation with agricultural productivity in tropical landscapes.