Assessing habitat selection of the vulnerable Asian small-clawed otters in an anthropized riparian forest of eastern Bangladesh

The Asian small-clawed otter (Aonyx cinereus) is a globally vulnerable mesopredator endemic to South and Southeast Asia. This species is one of the least studied and smallest of all 13 otter species. The species is tolerant of least-aquatic conditions and reported across a wide range of habitats. Its ecology is not fully and methodically deciphered. Recently, new populations were discovered in eastern Bangladesh, the north-western border of the Indo-Burma Biodiversity Hotspot. Based on camera trapping carried out between January and July 2021, we investigated otter occupancy and spatiotemporal coexistence within an anthropized riparian mixed-evergreen forest. We assessed the influence of stream density, the distance between the camera-trap station and the nearest built-up area, and slope on otter habitat use; cumulated precipitation and Julian day on detection probability. Our results revealed a mammalian mesopredator release effect and heavy anthropogenic activities; however, otters and humans exhibited very low spatiotemporal overlap. Detections showed high temporal convergence with the nocturnal-crepuscular carnivore guild. Otter occupancy did not show any pattern when modelled with altitude or human density; detection neither decreased with the progression of the monsoon. Our findings suggest that otters can adapt their habitat use to human pressure in forests dominated by human activities, especially with dense stream networks. We encourage further research to gain a better understanding of the factors that could impact otter habitat preference, such as food abundance, undergrowth vegetation, human-induced forest fires, and fishing or poaching pressure. Understanding otters is a potential tool to step up research investment in anthropized forests.

Automated summary

The Asian small-clawed otter is a globally vulnerable mesopredator found in South and Southeast Asia. It is one of the smallest and least studied otter species. A recent study in Bangladesh found that otters can adapt to human-dominated forests with dense stream networks, and have low spatial and temporal overlap with humans.