Modelling Range Trends of the Alpine Ibex Under Climate Change Scenarios

Abstract

Aim

High-altitude specialists such as the Alpine ibex are expected to be strongly affected by climate warming, but the magnitude and spatial patterns of future habitat losses across the Alps remain unclear. The aim of this work was to identify the major drivers of the Alpine ibex (Capra ibex) distribution and potential species range shift under two climate change scenarios, and to predict the potential IUCN Red List status according to habitat loss.

Location

European Alps (species' current distribution) plus a 100 km buffer for model calibration and within-range projections; mainland Europe and nearby islands for exploratory projections beyond the currently accessible range.

Taxon

Capra ibex.

Methods

An ensemble of four machine learning algorithms (i.e., Random Forest, eXtreme Gradient Boosting Training, Artificial Neural Network, and Generalised Boosting Model) was used to develop an Ecological Niche Model, which was then projected over a period of two decades, grouped around the years 2050 and 2070 under SSP2-4.5 and SSP5-8.5 scenarios using different Global Circulation Models. The amount of habitat lost was used to provide an indicative assessment of potential future conservation risk following the IUCN A3 (C) criterion.

Results

Annual mean temperature emerged as the most important predictor of habitat suitability. Under all scenarios, future projections highlighted severe losses of suitable habitat (i.e., up to 59.16% under SSP5-8.5 by 2070), especially in the Western Alps, potentially leading the species to be classified as endangered in the future under a worst-case scenario. Broader European projections identified out-of-range suitability mainly in Scandinavia and the Pyrenees, largely lost under future scenarios.

Main Conclusions

Climate change is expected to cause substantial habitat losses for the Alpine ibex across its range, even under intermediate scenarios, particularly in the Western Alps, underscoring the urgent need for conservation strategies that account for future climate conditions.