Population Size and Habitat Suitability of the Endangered Sichuan Sika Deer (Cervus nippon sichuanicus) in a Forested Landscape

Accurate estimation of population size and identification of key habitat factors are fundamental for the conservation of endangered species. This study demonstrates the application of advanced methods for estimating wildlife abundance and evaluating habitat associations for the endangered Sichuan sika deer (Cervus nippon sichuanicus) in the Gansu Taohe National Nature Reserve. We deployed a systematic camera trap network across the reserve and estimated population size by integrating camera trap data with a movement simulation method, while employing a Maximum Entropy (MaxEnt) model to analyze the effects of various environmental variables on habitat utilization. Our survey estimated a population of approximately 429 individuals (95% CI: 390–446), corresponding to a density of 0.15 individuals/km2. Habitat suitability modeling revealed that precipitation of the driest month (bio14; 44.5% contribution) and vegetation cover (NDVI; 39.1% contribution) were the predominant factors governing habitat suitability, collectively accounting for over 80% of the model’s prediction, whereas anthropogenic factors like the Human Footprint Index showed negligible independent importance. This study provides the first baseline population estimate for this endangered ungulate in the Taohe Reserve. The current low population density suggests substantial potential for recovery, indicating that future conservation strategies should safeguard key water sources and enhance habitat quality and connectivity.