An Estimation of Age and Life-Span of the Genus Trimeresurus (Reptilia, Serpentes, Viperidae) on Amami Oshima Island, Japan

Two species of snakes of the genus Trimeresurus, Trimeresurus flavoviridis and Trimeresurus okinavensis, inhabit Amami Oshima Island in the Loo-Choo Islands. These are the common terrestrial venomous snakes on Amami Oshima Island. There is a ring structure on the centra of vertebrae in these snakes. I tried to confirm by in vivo staining that rings on centra were formed annually. Then, age and life-span was estimated by Walford's graphic method. It appears that the age of these snakes can be estimated by adding total ring number +1. The life-span of Trimeresurus flavoviridis is estimated to be 10 years for ♂ ♂ and 7 years for ♀ ♀, where the estimated maximum total body lengths are 216.4 cm and 171.6 cm respectively. On the other hand, in Trimeresurus okinavensis, the life-span and calculated total body length of the oldest male are estimated to be 19 years and 144.6 cm respectively. In the oldest female the life-span and calculated maximum total body length are estimated to be 15 years and 130.3 cm respectively. Although estimated values of the total body length of Trimeresurus okinavensis do not agree with collecting data in the field, it appears that the life-span of the female of Trimeresurus okinavensis is longer than Trimeresurus flavoviridis.