Breeding habitat prediction and nest-site characteristics of the fairy pitta (Pitta nympha) in Geoje-si, South Korea: Insights from a distribution model

Abstract

The fairy pitta (Pitta nympha), listed as Vulnerable by the IUCN, breeds in forested valleys across East Asia, yet its nesting habitat in South Korea remains poorly characterized. This study aimed to identify key environmental drivers of nest-site selection and predict suitable breeding habitats in Geoje-si, a core breeding region in southern Korea. Field surveys conducted from 2019 to 2023 confirmed 47 nests, primarily located on rocky substrates or in the forks of large-diameter trees (>= 60 cm DBH). Using presence-only data, we developed a MaxEnt species distribution model incorporating ten ecologically relevant variables. Model optimization identified the LQH feature class with a regularization multiplier of 4 as the best-performing configuration, yielding strong predictive accuracy (AUC = 0.881 +/- 0.026). The most influential predictors were the Topographic Wetness Index (TWI), dominant tree species, and slope aspect, suggesting a preference for moist, broadleaf-dominated forests on southwest-facing slopes. Habitat suitability was concentrated in low-disturbance, structurally complex valleys, yet only 2.25 km2 (23.8 %) of the predicted high-suitability area overlapped with legally protected zones. These findings underscore a spatial mismatch between ecological value and conservation coverage, highlighting the need to expand protection to climatically buffered breeding habitats outside current protected areas.