Niche partitioning and population structure of sympatric mud snakes (Homalopsidae) from Bangladesh

Despite the greatest diversity of snakes being in the tropics, detailed ecological studies are rare, especially in tropical Asia. We studied the ecology of a coastal marine homalopsid (rear-fanged, aquatic snakes) assemblage in southeastern Bangladesh. Data were collected on community structure, resource partitioning (diet and habitat), body size and sexual size dimorphism. A total of 653 specimens belonging to three species were collected: Cerberus rynchops (81% of total capture), a medium-sized piscivorous snake, found to be the most abundant species in the study site followed by two crustacean eaters, Gerada prevostiana (13%) and Fordonia leucobalia (6%). The three species were relatively similar in terms of body size but were inconsistent with each other both in terms of morphological patterns and demography characteristics, with sex-ratio being equal in two species but female-biased in G. prevostiana. There was no apparent non-random resource partitioning along the microhabitat axis but a clear pattern of niche partitioning was observed along the food axis. Despite the very unusual evolutionary history of the Homalopsidae inside the group of the Colubroidea, our snake assemblage very closely resembled other communities of snakes worldwide.