U.S. Department of Agriculture: Animal and Plant Health Inspection Service


Date of this Version

April 1999


RODDA, G. H., T. H. FRITTS, and E. W. CAMPBELL 111. 1999. The feasibility of controlling the brown treesnake in small plots. Pages 469-477 in Rodda, Gordon H., Sawai, Yoshio, Chiszar, David, and Tanaka, Hiroshi, editors. Problem snake management : the habu and the brown treesnake . Cornell University Press, Ithaca, NY. 5340. Permission to use.


There is an urgent need to provide snake-free or snake-reduced habitats for the wildlife species on Guam that have declined or disappeared as a result of predation by the Brown Treesnake, Boiga irregularis (Savidge, 1987; Fritts, 1988; Rodda and Fritts, 1992; Rodda et al., this volume, Chap. 2). At present, we know of no practical techniques for reducing or eradicating the snake throughout Guam, a densely populated island of 54,100 ha. Conserving native wildlife and reducing the incidences of snakes boarding ship and aircraft may not require the elimination of snakes from the entire island, however. Elimination of snakes from critical wildlife habitats and sanitized zones in the vicinity of ports and airports would be a worthwhile accomplishment, and recent breakthroughs in trapping technology suggest that local elimination may be feasible.

The capture success rates of recent trapping studies provide some guideposts for assessing the practicality of snake control effectiveness in small plots. Assuming that immigration, emigration, and recruitment are negligible, and that all snakes exhibit capture probabilities equal to the mean of their class in recent trapping experiments (Table 39.1), snake populations will decline exponentially as control measures are applied. The theoretical number of snakes never reaches zero under such conditions; however, if the number of snakes remaining is near zero, we can justifiably relax. In the work reported below, we used a criterion of having less than 0.1 hypothetical snake remaining.