Predicting the distribution of Blyth's kingfisher (Alcedo hercules) in the Eastern Himalayas: a climate-sensitive ensemble modelling approach

Abstract

In the context of changing climatic conditions, species distribution modeling emerges as a crucial tool for estimating the potential impact of climate variables on species' habitat ranges. The Eastern Himalayan region is highly susceptible and vulnerable to the impacts of climate change. However, there is limited understanding of how these climate changes affect the habitats of bird species with restricted ranges, which are vulnerable in the region. This study aims to identify the key environmental variables shaping the distribution of Alcedo hercules and to predict its potential range under current and future climatic scenarios (SSP245 and SSP585). An ensemble modeling approach, integrating MaxEnt, random forest (RF), generalized linear model (GLM), support vector machine (SVM), and multivariate adaptive regression splines (MARS), was employed using climate projections from the HadGEM3-GC31-LL global climate model. To predict the potential suitable habitats, 10 predictor variables were used to model the potential suitable habitat distribution of A. hercules. The findings revealed that under current climatic conditions, approximately 7078.17 km² (2.25% of the total area) was identified as a highly suitable habitat for the A. hercules. However, future projections suggest a significant reduction in highly suitable habitat, with more than 12.95% expected to be lost by 2041-2060 under the SSP585 scenario. The ensemble model performed robustly and was found to be excellent performance based on AUC value of 0.90 and TSS value of 0.66. The top three key variables, such as the mean diurnal range (mean of monthly (max temp-min temp)), precipitation seasonality (coefficient of variation), and precipitation of the coldest quarter, emerged as dominant variables, with a total contribution rate of 52.37% to the current distribution. The habitat suitability analysis for A. hercules can offer baseline data on their current and future suitable habitat for this species. The projected reduction in suitable habitats for A. hercules under future climate scenarios highlights the urgent need for proactive conservation strategies. Habitat loss could have significant consequences for the species, potentially leading to population declines, disrupted ecological interactions, and reduced genetic diversity.

Keywords: Alcedo hercules; Climate change; Conservation; Eastern Himalayas; HadGEM3-GC31-LL; Near Threatened.