Predicting the Distribution Pattern of Small Carnivores in Response to Environmental Factors in the Western Ghats

<div><p>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 <i>F. chaus</i>, <i>P. hermaphroditus</i>, and <i>H. smithii</i> “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 <i>V. indica</i> while “distance to village” and precipitation of the coldest quarter were significant for <i>H. vitticollis</i>. “Distance to village”, precipitation of the warmest quarter and land cover were influential variables in the distribution of <i>H. edwardsii</i>. The map of predicted probabilities of occurrence showed potentially suitable habitats accounting for 46 km² of the reserve for <i>F. chaus</i>, 62 km² for <i>V. indica</i>, 30 km² for <i>P. hermaphroditus</i>, 63 km² for <i>H. vitticollis</i>, 45 km² for <i>H. smithii</i> and 28 km² for <i>H. edwardsii</i>. 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.</p></div

Habitat suitability maps of small carnivores based on MaxEnt models using environmental variables.

<p>Average MaxEnt predictions from 40 runs for each species at the scale of 1×1 km resolution. The predicted probability of presence, with values ranging from 0 to 1, is depicted by different colours. Using the MaxEnt logistic output, red colours indicate a higher “probability of occurrence” (suitability) while the blue colours indicate lower probabilities.</p

Location of the study area showing the spatial distribution of camera-traps and vehicle transect routes in Mudumalai Tiger Reserve (2010 and 2011).

<p>Location of the study area showing the spatial distribution of camera-traps and vehicle transect routes in Mudumalai Tiger Reserve (2010 and 2011).</p

Response curves for the most significant predictors of habitat suitability of small carnivores according to the MaxEnt model.

<p>The response curve is shown in different colours. Each colour represents a different species. The dark grey and light grey dotted lines represent 95% confidence intervals from 40 replicated runs.</p

Average estimates of Maxent distribution models for small carnivores in Mudumalai Tiger Reserve (2010 and 2011).

<p>The model performance was computed on different test data set.</p

The study area, Sariska Tiger Reserve, Rajasthan, India.

<p>The study area, Sariska Tiger Reserve, Rajasthan, India.</p

Generalized linear model (with Poisson distribution and identity function) of factors that influenced fecal glucocorticoid metabolite concentrations in tigers of Sariska Tiger Reserve (2011–2013).

<p>*—Beta or Coefficient</p><p>^#- Degrees of Freedom</p><p>^$Sig. is Significant level at 95% Confidence Interval</p><p>Generalized linear model (with Poisson distribution and identity function) of factors that influenced fecal glucocorticoid metabolite concentrations in tigers of Sariska Tiger Reserve (2011–2013).</p

Percentage of radio location of tigers in different disturbed areas and respective (subset figures) mean faecal glucocorticoid metabolite concentration in Sariska Tiger Reserve.

<p>(Red- high disturbance, yellow—medium disturbance, green—less disturbance zones and blue—overall mean +/- SE).</p