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Anthropogenic threats like illegal fishing and sand mining pose a threat to the mugger crocodiles (Crocodylus plaustris) of the Rapti river flowing along the Chitwan National Park (CNP) in south-central Nepal, contiguous to the Valmiki Tiger Reserve in Bihar, according to a recent study.
The researchers found that there were 46 muggers in the stretch of the Rapti that they surveyed. The animals were most likely to be found on moderate or moderately steep banks of the river.
A win-win conservation situation between vulnerable muggers and the local community is necessary for the viable and long-term conservation of muggers in the Rapti river, the researchers wrote.
The scientists urged the authorities of CNP “to prioritise integrating local ethnic and river-dependent communities into effective conservation and management programmes with livelihood opportunities”.
The mugger or marsh crocodile is one of the 24 extant species of crocodilians found globally. It is found India, Pakistan, Nepal and Iran.
The species is listed as ‘Vulnerable’ in the International Union for Conservation of Nature’s Red List. It has been enlisted on Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora since 1975.
In Nepal, muggers are found in the Terai lowlands near the border with India. A study last year noted that the species has become extinct locally in many parts of Nepal due to habitat loss despite being protected by law.
Status, distribution and habitat use by Mugger crocodile (Crocodylus palustris) in and around Koshi Tappu Wildlife Reserve, Nepal published in August 2022, noted that:
The countrywide population of mugger is not available, however it is predicted that the total population of muggers in Nepal is between 400 and 500.
The authors of the CNP study embarked on their research as not much is known about the species, with more focus being on its cousin, the gharial (Gavialis gangeticus):
Muggers have a sympatric distribution with gharials in the Rapti and Narayani River of Chitwan National Park, but more research and conservation attention has been focused on gharials in Nepal.
This dearth of data on the occupied habitats of muggers restrict their evidence-based conservation and management. “Therefore, we investigated the ecological factors affecting the habitat selection of muggers and its conservation threats in the Rapti River,” the authors wrote.
They conducted a preliminary survey, followed by a detailed habitat survey, in February and March 2022.
The Rapti originates in the Mahabharat Hills and lower range of the Himalayas and flows westward along the northern border of the CNP. The surveys were conducted along a 52 km river stretch from Jindagani Ghat (the eastern side) to Golaghat (Rapti-Narayani confluence) on the western side.
The researchers examined the presence or absence of muggers along the stretch based on:
Besides the finding about mugger presence mostly along river bank stretches with moderate and moderately steep slopes, the most severe conservation threats to the animals were also ranked. These were fishing and extracting river materials and disposal of garbage and solid waste.
The authors suggested that park authorities provide local communities with nature guide training, low interest bank loans for crop/vegetable farming and job recruitment in the park office to reduce risks to muggers.
“Our study has highlighted the urgent need for effective conservation and management of the remaining mugger population in the Rapti River against emerging anthropogenic threats,” they wrote.
Factors influencing the habitat selection of Mugger crocodile (Crocodylus palustris) and its conservation threats in the Rapti River of Chitwan National Park, Nepal has been published in the April issue of Global Ecology and Conservation.