Habitat Management of Mugger Crocodile (Crocodylus palustris) through Regional- Scale Niche Modeling for Practical Conservation Planning

Document Type : Research Paper

Authors

1 ‎Department of Environmental Sciences, Faculty of Natural Resources, University of Zabol‎, ‎Zabol, Iran

2 ‎Department of Environmental Sciences, Faculty of Fisheries and Environmental Sciences, Gorgan ‎University of Agricultural Sciences and Natural Resources, Gorgan, Iran‎

Abstract

Objective: Macro-environmental variables influence the distribution of species on a regional scale, and bioclimatic variables are the most important among them. The mugger crocodile (Crocodylus palustris), which is a keystone species and the only crocodile in Iran, needs freshwater habitats to survive in regions with low precipitation. Also, every temperature fluctuation in the nest location impacts the sex ratio of its offspring. Consequently, the continuity of survival of this cold-blooded species is fundamentally influenced by climatic conditions rather than other ecological conditions on a regional scale. Therefore, this study was conducted on habitat modeling of the mugger crocodile using historical bioclimatic variables on a regional scale.
Methods: In the present study, habitat suitability modeling for the mugger crocodile was conducted using maximum entropy modeling (MaxEnt) and bioclimatic variables extracted from the KGClim_V1 climate model database. Bioclimatic variables were screened based on their correlation and the variability of each dataset, as assessed through standard deviation (SD), ultimately leading to the selection of seven from an initial dataset of twelve variables. Using species presence data as the dependent and bioclimatic variables as independent variables, the MaxEnt model was executed with 15 repetitions to identify potentially suitable areas for the species at regional scale based on the average results from the repetitions.
Results: The modeling results indicated that the highly suitable habitat areas were located near the observation points of the species. This finding reflected a significant gain associated with a high area under the curve (AUC) value of 0.938. The jackknife test identified the most effective climatic variables, including PWM, PWMwint, and Tavg. According to the logarithmic response curves of this species to rainfall bioclimatic variables, suitable habitat areas were predicted to be in regions with low rainfall. By comparing the results with those of other studies, it was concluded that different scales of biological, ecological, geographical, and human factors influence the species distribution. Therefore, predicting species distribution across multiple spatial scales is essential for a more accurate valuation of the relationships among these variables.
Conclusions: The findings of this study showed the necessity of integrated watershed management, especially in upstream areas, to ensure the survival of mugger crocodile downstream. Accordingly, a hierarchical modeling approach was recommended for future studies utilizing environmental variables at different scales. This approach is based on modeling macro factors separately from local-scale influences. In this context, micro and macro-scale studies are both important; however, their integration may pose problems because of inconsistency in spatial resolution and the scale of their effect on the species.

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References

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Journal of Environmental Studies
Volume 51, Issue 1
June 2025
Pages 41-58

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