REPRODUCTIVE BIOLOGY AND NATURAL HISTORY OF THE WHITE-LIPPED PIT VIPER (TRIMERESURUS ALBOLABRIS GRAY, 1842) IN HONG KONG

The White-lipped Pit Viper (Trimeresurus albolabris) is broadly distributed through South and Southeast Asia, and very little is known about the natural history of the species. In this study, we report on the ecology, demography, reproductive states, and growth rates of T. albolabris in Hong Kong, China. The sex ratio is even in Trimeresurus albolabris populations. This species displays sexual dimorphism from birth. Females attain larger sizes, and all males, including neonates, displaying a white supralabial stripe on the head and have longer relative tail lengths. Males attain sexual maturity at about 410 mm snout-vent length (SVL). Females reach sexual maturity at about 460 mm SVL, but only begin reproducing at about 520 mm SVL. Mating occurs between August to October, coinciding with the onset of spermatogenesis. Trimeresurus albolabris displays post-nuptial vitellogenesis, and long-term sperm storage in females likely occurs over the winter. Females gestate over the summer and parturition occurs in late July to August. Females reproduce once every two or more years, except for very large females that may reproduce annually. Brumation by females occurs within the first three weeks of December, but snakes will emerge to bask on sunny days. Understanding its demography and reproductive ecology can provide insights into the conservation and management of T. albolabris populations in the region and increase our understanding of sexual dimorphism, reproduction, and evolution of the cryptic Trimeresurus species complex.