Habitat Use by Gharial and Mugger Crocodile in Rapti River, Chitwan National Park, Nepal

Abstract

In Nepal, two crocodilians, Mugger (Crocodylus palustris) and Gharial (Gavialis gangeticus), share a sympatric range in the Rapti River in Chitwan National Park. To better understand the influence of different habitat characteristics on the distribution of these crocodiles and aid in their conservation, a study was conducted between February and March 2023. The study collected data along the river, focusing on habitat characteristics at 500-meter intervals and areas where both species were observed. Generalized Linear Model with binary logistic regression was used for statistical analysis. This model helped to examine the presence or absence of Mugger and Gharial at different sampling points, using seven habitat characteristics as predictors. These predictors included the slope and aspect of the river bank, distance to the forest and human settlements, level of human disturbances, water current, and river bank substrate type. The statistical significance of these predictors was assessed using the likelihood ratio test, and the probability of crocodile sightings in relation to habitat variables was determined using the Akaike Information Criterion. The results of the analysis showed that human disturbances and water currents were significant factors influencing the presence of Gharials. On the other hand, only the slope of the river bank was found to be a significant factor in the presence of Muggers at specific sampling stations. These findings highlight that Gharials and Muggers have distinct habitat preferences, emphasizing the importance of effective habitat management by the concerned authorities. The study underscores the necessity of considering these influential factors in conservation efforts aimed at protecting the Mugger and Gharial species in the Rapti River. By understanding their specific habitat requirements and promoting suitable coexistence, conservationists can contribute to the effective conservation of these crocodilians.