A mark-recapture study of a dog-faced water snake Cerberus schneiderii (Colubridae: Homalopsidae) population in Sungei Buloh wetland reserve, Singapore

Abstract

Ecological traits of a relatively sheltered population of the dog-faced water snake, Cerberus schneiderii, were determined or estimated using mark-recapture data. Monthly surveys were conducted at the man-made brackish ponds at Sungei Buloh Wetland Reserve, Singapore throughout the year 2006. Estimates of population density (102 snakes ha-1), snake biomass (4.1 kg ha-1) and relative abundance (5.4 snakes man-hour-1) provided evidence of a large population. Sex ratio was almost 1:1. Snakes from a wide range (145-720 mm SVL) of body size were present. Even though neonates were rarely encountered, 88.7% of adult females have reached the size of sexual maturity (SVL = 336 mm SVL). There was no seasonal variation in the population's size structure, suggesting that recruitment occurred throughout the year. Most of the snakes were sedentary and more than 90% of them remained in the same pond that they were captured for the first time. During low tides, snakes had a tendency of congregating at the relatively deep waters close to the sluice gates and in the network of tidal streams and pools in the man-made ponds. The population exhibited sexual dimorphism, in terms of males having relatively longer tails and females possessing relatively wider heads. © National University of Singapore.