The first of sixteen white-lipped island pit vipers (Trimeresurus insularis) we found in the Lesser Sundas last week. Yes, sixteen! We were incredibly lucky. T. insularis comes in three relatively discrete morphs: blue, yellow, and green. Blue phase only occurs on Komodo and Padar island, yellow on Flores, and green throughout the Lesser Sundas. Much like the eyelash viper (Bothriechis schlegelii) in the New World, it would be interesting to understand the selective pressures driving variation in color. In particular, if one morph can have a mixed litter of morphs, why does the abundance/presence of morphs differ geographically?
White-lipped island pit vipers have a conspicuous red stripe running down the dorsal surface of the tail tip, almost as if it had been dipped in red paint. Caudal luring is employed by raising and undulating the tail in a worm-like manner to attract prey. Skinks in the genus Sphenomorphus are extremely abundant in the islands we visited and likely make up a great portion of the vipers’ diet. A red small wriggling worm must be practically irresistible to a foraging skink. Death adders (Acanthophis spp.) and many vipers are also known to caudal lure, a behavior I’ve always wanted to observe in the wild.
Spotted cruising along the forest floor at night on Pulau Komodo in the Lesser Sundas