Zoological Studies

Vol. 46 No. 2, 2007

Diurnal Retreat Site Selection by the Arboreal Chinese Green Tree Viper (Trimeresurus s. stejnegeri) as Influenced by Temperature

Hwa-Ching Lin1,2, Hsin-Yi Hung2, Kuang-Yang Lue1, and Ming-Chung Tu1,*

1Department of Life Science, National Taiwan Normal University, Taipei 116, Taiwan
2Animal Department, Taipei Zoo, Taipei 116, Taiwan

Hwa-Ching Lin, Hsin-Yi Hung, Kuang-Yang Lue, and Ming-Chung Tu (2007) We investigated the role of vegetation cover, prey availability, and air temperature on the selection of a retreat site by the Chinese green tree viper (Trimeresurus s. stejnegeri), a nocturnal, arboreal sit-and-wait predator. We manipulated the vegetation structure and distance to the prey source, and monitored the microhabitat temperature within the test enclosures. The results indicated that the height of the daytime perch sites was influenced by the ambient temperature. Snakes perched on lower layers of vegetation seeking cooler conditions when the ambient temperature within the enclosure was high. In addition, when the ambient temperature rose above 25C, tree vipers retreated into denser vegetation, which provided significantly lower temperatures due to shading. In contrast, tree vipers in low-temperature environments exhibited no preference for vegetation structures in terms of density, except for an apparent avoidance of vegetation with bare branches and no leaves. The distance to the prey source did not appear to have any significant influence on the green tree viper's selection of a retreat site; this could be attributed to the fact that these snakes hunt both terrestrial targets and arboreal species. Our study demonstrated that temperature is the most important factor influencing retreat site selection by Chinese tree vipers. The temporal variations and seasonal differences in the space utilization patterns may have been attempts to satisfy their thermoregulation needs.

Key words: Microhabitat selection, Temperature, Retreat site, Snake, Vegetation density.

*Correspondence: Tel: 886-2-29336875 ext. 321. Fax: 886-2-29312904. E-mail:biofv026@scc.ntnu.edu.tw