Delivery of Duvernoy's secretion into prey by the brown tree snake, Boiga irregularis (Serpentes : Colubridae)

Many colubrid snakes, like the more venomous elapid and viperid snakes, can produce and inject an oral secretion that is toxic and may present a human health risk. However, colubrid oral toxins are produced in a Duvernoy's gland and delivered not through a hollow fang, but instead by long, often grooved teeth under low pressure. The possible role of Duvernoy's secretion in functions other than rapid killing of prey make it important to know how and where this secretion is delivered during a feeding strike. We used ELISA analysis to determine the quantity and proportional distribution of Duvernoy's secretion delivered into the integument compared to the viscera during a feeding strike by the colubrid snake Boiga irregularis. We determined that only about 54% (1-5 mg) of the secretion actually reached the viscera and that the rest remained in the integument. The amount reaching the viscera is about three to eight times the i.p. ld₅₀ for mice, but these snakes depend more on constriction than toxins to kill their prey. Consequently, delivery of Duvernoy's secretion by B. irregularis is hypothesized to be part of a digestive function and its toxic properties a by-product of this role.