New developments in snake barrier technology: fly-ash covered wall offers a feasible alternative for permanent barriers to brown treesnakes (Boiga irregularis)

Published source details Rodda G.H., Farley J.L., Bischof R. & Reed R.N. (2007) New developments in snake barrier technology: fly-ash covered wall offers a feasible alternative for permanent barriers to brown treesnakes (Boiga irregularis). Herpetological Conservation and Biology, 2, 157-163.
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Summary

Accidental introduction of the brown tree-snake Boiga irregularis to Guam in the late 1940s (and subsequent predation) is considered to be responsible for the extunction or decline of most of the island’s native (many endemic) vertebrate species. Effective barriers to its movement will reduce risk of dispersal from Guam and prevent re-colonization of areas on the island subject to snake control. In this study, the effectiveness of a fly-ash covered wall design as a barrier was trialled.

Wondertec™ International, manufactures walls made of a durable fly ash material plastered onto a wooden frame, and are about 20% cheaper to fabricate and install than concrete designs tested to date. A section of wall (1.82 m long x 1.46 m high, horizontal overhang protruding perpendicularly for 20 cm on each side at 1.2 m) with two surface types (rough and smooth) was tested by providing snakes access to the wall as the only potential escape route from a test chamber. The smooth finish had a texture similar to a concrete design previously trialled; the rough finish was comparable to medium grade sandpaper.

The rough finish was tested from 10 January to 5 May 2005 and the smooth from 3 August to 22 November 2005. Snake behaviour over each 2-night test period (12 h darkness) was monitored using an infra-red camera and time-lapse video-cassette recorder. The widest possible range of snake size (wild-caught individuals) was used.

None of 100 snakes tested on the smooth finish scaled the wall (202 snake-nights; 612 climbing attempts recorded). Out of 153 snakes tested on the rough finish, only one individual (extremely large) breached the wall (306 snake-nights, 1,533 attempts recorded).

The authors conclude that this wall design may provide a feasible and cost effective alternative to existing wall designs if it meets criteria for durability under environmental conditions present on Guam.

Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://www.herpconbio.org/Volume_2/Issue_2/Rodda_etal_2007.pdf