Predicting Habitat Suitability of Range-restricted Bird, Phylloscopus tytleri under Projected Climate Change Scenario

Abstract

Climate change poses a significant threat to mountain ecosystems by altering the distribution of climatically suitable habitat for range-restricted species. This study forecasts potential habitat changes for Phylloscopus tytleri (Tytler’s Leaf Warbler), a near-threatened Himalayan passerine with a narrow breeding distribution that is particularly vulnerable to environmental change. The Maximum Entropy (MaxEnt) model was used to predict the current and future habitat suitability of Phylloscopus tytleri in the Western Himalaya using occurrence records from field surveys and the eBird database. The environmental predictors included bioclimatic, topographic, vegetation and soil variables. Future habitat suitability was projected for 2070 under three climate scenarios (RCP 4.5, RCP 6.0 and RCP 8.5). The model performance indicated reliable predictive accuracy, with AUCtrain = 0.88 and AUCtest = 0.84, and TSS and Kappa values of 0.73 and 0.74, respectively. Variable-importance analysis identified annual temperature range as the most influential predictor, followed by precipitation of the coldest quarter, isothermality, slope and precipitation of the warmest quarter. Habitat projections revealed a pronounced decline in suitable habitat across all future climate scenarios, indicating a progressive reduction in climatically favourable areas. The contraction of highly suitable areas suggests increased vulnerability of this range-restricted species under future climate change. These findings highlight the importance of incorporating climate projections into conservation planning by prioritising climatically stable habitat, maintaining habitat connectivity and implementing adaptive management strategies.