Sexual dimorphism and reproductive biology of the Asian bockadam snake (Cerberus schneiderii) in West Java

Although they are among the most abundant snakes on Earth, and are heavily exploited for their skins and meat, Asian bockadams (or “dog-faced water snakes”, Cerberus schneiderii) have attracted relatively little study across their wide geographic range. Based on dissection of 3,382 snakes brought to processing facilities in and around the city of Cirebon in West Java, Indonesia, we document facets of the biology of these mangrove-dwelling aquatic homalopsids. Females attain larger body sizes than do males, and are heavier-bodied (due in part to greater fat reserves) but have shorter tails relative to snout-vent length. Males showed testicular enlargement late in the year (August-November) but both reproductive and non-reproductive females were found year-round. Litters were large (3 to 45 offspring), especially in larger females. The commercial harvest falls mainly on adult snakes of both sexes, with seasonal variation in sex ratios. Life-history traits such as early maturation and frequent production of large litters render this species resilient to commercial harvesting. Future research should explore reasons for strong variation among facilities in the sex ratios of snakes, potentially identifying ways to focus the harvest on the sex (males) whose numbers are less critical for population viability.