Abstract
Due to their secretive habits, predicting the pattern of spatial distribution of small carnivores has been typically challenging, yet for conservation management it is essential to understand the association between this group of animals and environmental factors. We applied maximum entropy modeling (MaxEnt) to build distribution models and identify environmental predictors including bioclimatic variables, forest and land cover type, topography, vegetation index and anthropogenic variables for six small carnivore species in Mudumalai Tiger Reserve. Species occurrence records were collated from camera-traps and vehicle transects during the years 2010 and 2011. We used the average training gain from forty model runs for each species to select the best set of predictors. The area under the curve (AUC) of the receiver operating characteristic plot (ROC) ranged from 0.81 to 0.93 for the training data and 0.72 to 0.87 for the test data. In habitat models for F. chaus, P. hermaphroditus, and H. smithii “distance to village” and precipitation of the warmest quarter emerged as some of the most important variables. “Distance to village” and aspect were important for V. indica while “distance to village” and precipitation of the coldest quarter were significant for H. vitticollis. “Distance to village”, precipitation of the warmest quarter and land cover were influential variables in the distribution of H. edwardsii. The map of predicted probabilities of occurrence showed potentially suitable habitats accounting for 46 km2 of the reserve for F. chaus, 62 km2 for V. indica, 30 km2 for P. hermaphroditus, 63 km2 for H. vitticollis, 45 km2 for H. smithii and 28 km2 for H. edwardsii. Habitat heterogeneity driven by the east-west climatic gradient was correlated with the spatial distribution of small carnivores. This study exemplifies the usefulness of modeling small carnivore distribution to prioritize and direct conservation planning for habitat specialists in southern India.
Highlights
Predictive habitat modeling and mapping are useful in conservation planning, detecting distributional changes from monitoring data and quantifying variation in species performance towards several controlling factors
We considered all overlapping records as a single record, only spatially independent locations were selected for further analysis resulting in a final number of 36 point localities for F. chaus, 51 for V. indica, 22 for P. hermaphroditus, 55 for H. vitticollis, 51 for H. smithii and 35 for H. edwardsii (Figure 2)
In H. smithii models based on percent contribution, ‘‘distance to village’’ showed the greatest impact on species distribution (34.49%) followed by bio18 (29.4%) and models based on permutation importance showed that bio18 was the most influential variable (31.63%) followed by ‘‘distance to village’’ (31.63%, Figure S1(E))
Summary
Predictive habitat modeling and mapping are useful in conservation planning, detecting distributional changes from monitoring data and quantifying variation in species performance towards several controlling factors. Studies performed at smaller scales are essential for accurate understanding of ecological interactions and identifying drivers of species distributions for immediate conservation actions [4]. The Western Ghats has been listed as a World Heritage Site by the United Nations Educational, Scientific and Cultural Organisation (UNESCO). It is one of the world’s eight ‘‘hottest hotspots’’ of biodiversity [5] including globally significant populations of 13 small carnivore species; viz four species of small felids, four herpestids, four viverrids and five mustelids. Conducting focal studies on small carnivores is a daunting task as procuring government funds for conservation measures represents a huge challenge
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