Niche Partitioning and Facilitative Coexistence of Two Sympatric Pheasants Across a Gradient of Human Disturbance

How ecologically similar species coexist in human-impacted tropical islands remains poorly understood. We investigated the spatiotemporal niche partitioning and interspecific interactions between the endangered, endemic Hainan Peacock-Pheasant (Polyplectron katsumatae) and the more common Hainan Silver Pheasant (Lophura nycthemera whiteheadi) to assess how anthropogenic pressure mediates their coexistence. Using 125 camera traps (28,241 trap-days) and hierarchical Bayesian occupancy modeling, we quantified their activity patterns, habitat preferences, and spatial associations across a human disturbance gradient in Hainan's tropical montane rainforest. The pheasants exhibited clear temporal segregation: the Peacock-Pheasant was strictly crepuscular, whereas the Silver Pheasant was diurnal with a single morning peak, and their activity overlap was lower in the wet season than in the dry season. Spatially, they showed contrasting preferences: the Silver Pheasant occupied higher elevations with high NDVI, while the Peacock-Pheasant preferred mid-elevations with medium NDVI and proximity to water in the dry season. Despite this niche differentiation, a significant positive spatial association was detected (Species Interaction Factor: 2.48-3.01), indicating co-occurrence was more frequent than expected by chance. However, human disturbance critically modulated this relationship. The Peacock-Pheasant was extremely disturbance-sensitive, its occupancy declining to near zero in areas of high human impact. The Silver Pheasant exhibited greater tolerance, with occupancy peaking at intermediate disturbance levels. Our results demonstrate a coexistence mechanism stabilized by multidimensional niche partitioning but rendered conditional and fragile by anthropogenic pressure. Conservation must prioritize protecting core habitats for the sensitive Peacock-Pheasant while maintaining landscape connectivity and managing disturbance gradients to preserve this intricate interspecific dynamic.