Vol. 46 No. 5, 2007

When Prey Acts as a Lever: Prey-Handling Behavior of the Chinese Green Tree Viper, Trimeresurus stejnegeri stejnegeri (Viperidae: Crotalinae)

Tein-Shun Tsai

Department of Life Science, National Taiwan Normal University, 88 Ting-Chow Rd., Sec. 4, Taipei 116, Taiwan

Tein-Shun Tsai (2007) Snakes may use tongue flicking and snout touching to locate the head-end of immobilized prey, but tongue use is limited when snakes are holding prey after a strike. In this condition, how can they differentiate the anterior and posterior ends of the prey so that they still ingest their prey mainly from the anterior end? To answer the question, I analyzed the prey-handling behavior of Trimeresurus stejnegeri stejnegeri (Viperidae: Crotalinae) in the laboratory. Following the capture of a prey, T. s. stejnegeri lifted the prey from the ground. The prey thus hung in the air, with the body tilted, like a lever with the fulcrum at the site of the bite. In most cases, the snake gradually maneuvered its jaw to the higher end of the prey and began ingesting it. As an adaptation for arboreal feeding, the direction of prey ingestion in T. s. stejnegeri depended largely on the location of the initial bite site, under the proposed action of gravity. A significantly greater proportion of frogs (42.1%) were struck in the posterior region than mice (9.6%). The ratio of prey ingested from the anterior to the posterior ends was 54: 19 for mice and 24: 14 for frogs.

Key words: Arboreal pit viper, Feeding behavior, Ingestion direction, Gravity.

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