Intraspecific Variation in the Feeding Ecology of the Crotaline Snake Calloselasma rhodostoma in Southeast Asia

Abstract

TWO hundred twenty five prey items were identified from the stomach contents and faeces of museum specimens, roadkills, and live Calloselasma rhodostoma collected throughout Southeast Asia. Overall, this snake was found to eat a broad range of vertebrate and invertebrate prey, but exhibited strong intraspecific variation in its diet Ontogenetic variation was evident in all regions, typically expressed as a transition from predominantly ectothermic prey (arthropods, amphibians, and/or reptiles) to endothermic prey (mammals and birds), although the opposite trend occurred in parts of Thailand. Among snakes of similar size, significant geographic variation emerged in the proportions of different prey taxonomic classes constituting diet Sexual variation in prey type was also detected and feeding behavior changed according to reproductive status: gravid female pitvipers ceased feeding, and adult males appeared to fast during the mating season. Possible reasons for intraspecific variation in feeding ecology are discussed.