Wildlife Damage Management
Brown Treesnake Research at NWRC
Repellents or irritants are important for driving brown treesnakes
from areas where they can easily be concealed, such as cargo areas and transport
vessels. For example, when Wildlife Services personnel began working with
snake-detecting dogs in Guam, though a dog would indicate the presence of
a snake in the cargo, there was be no easy way to drive the snake from its
hiding place making it difficult to ensure that shipments were snake-free.
NWRC scientists have been looking at natural products as repellents. Most of these products have been approved by the U.S. Food and Drug Administration for human consumption. These compounds require minimal support data and do not require registration by the U.S. Environmental Protection Agency because they are already listed as safe by the Agency. Recent compounds tested, such as cinnamon oil, clove oil, and eugenol are now available for use. These compounds are considered environmentally benign and require no registration at all. Some of the compounds tested seem to uniquely affect snakes and do not appear to affect mammals or birds.
Once a compound is identified as a possible repellent, field tests must be performed and delivery mechanisms developed. Cold buoyant fogs and vapor buoyant forms are being tested as delivery mechanisms because they penetrate well and don’t destroy repellency of compounds (as has been the case with thermal fogs). A compound such as concentrated cinnamon oil (as used in cooking) can be put on wicks and the scent forced by blowers into hiding spots, driving snakes out of concealed areas. Aerosols have worked well in tests where the snake was directly in line of sight. Repellents or irritants that show near 100% efficacy at causing snakes to leave hiding places, when available, could be widely applied to the cargo leaving Guam, preventing snakes from spreading to other locations.
October 11, 2007