Favourable climatic niche in low elevations outside the flood zone characterises the distribution pattern of venomous snakes in Bangladesh

Abstract

Snakes are sensitive to both environmental and climate gradients. To design conservation plans, a scientific understanding of snake habitats in light of environmental and climatic variables is an essential prerequisite. For venomous snakes, denoting favourable habitats should also be relevant for snakebite management. We have considered 18 spatial variables to portray the range of terrestrial venomous snake distribution in Bangladesh. Our results indicate that the distribution of 29 studied venomous snakes in this country is primarily driven by climatic and environmental variables. We found that especially low elevation and flood risk constrain the distribution of those terrestrial snakes, i.e. regular floods in central Bangladesh push venomous snakes towards the edges of the country. Moreover, none of these species occupies the whole of its anticipated climatically favourable area. Projections into the future indicated that 11 studied species, Amphiesma platyceps, Boiga siamensis, Chrysopelea ornata, Pseudoxenodon macrops, Rhabdophis himalayanus, Rhabdophis subminiatus, Bungarus lividus, Ophiophagus hannah, Daboia russelii, Ovophis monticola and Trimeresurus popeiorum will lose their entire climatically suitable area within the country. Therefore, we suggest establishing more protected areas in the hilly ecosystems in the eastern part and in the mangrove forests in the south-western corner of Bangladesh to mitigate future extinction risks, such as climate change, sea-level rise and increase in flood severity. Conserving village forests and croplands, which are subject to rapid change, will also need to be addressed equally, as these are inhabited by almost one-third of the studied species. The occurrence of the cobras and kraits in village forests and cropland dominant habitats demands more attention to minimise snakebite related mortality and morbidity.