Control and Containment Strategies on Guam: Habitat Modification
Brown Treesnakes are successful on Guam due in large part to high prey densities associated with the ecology of oceanic islands and habitat tolerances common in secondary growth habitats that are widespread on Guam. In particular, forested areas in and near transportation and cargo handling areas can harbor abundant prey, including rats, introduced birds, and lizards; provide daytime refugia for snakes; and furnish cover hampering visual detection of snakes. Clearing these areas often represents an effective and relatively inexpensive tool to augment other control methods, such as trapping and visual searches. Removing vegetation eliminates potential prey and snakes, rendering the area largely unsuitable for the existence of either. It also reduces the chances of snakes entering adjacent structures and facilitates the detection of any individuals that may move across cleared areas.
Large amounts of debris and refuse near many warehouses, comprised of abandoned automobiles, old pallets, and other junk, also provide havens for snakes and prey. Simply cleaning these areas can reduce the number of snakes present in an area and facilitate the detection and capture of any individuals remaining or subsequently moving through the areas. Examples include eliminating refuse near cargo assembly areas and warehouses and repairing buildings to prevent rodents and snakes from entering and also discouraging nesting by introduced birds. Commercial areas are further controlled by using Environmental Protection Agency registered rodenticides to reduce rat populations at transportation facilities and cargo packing areas. This reduces potential prey numbers and the attraction that such prey furnish for foraging snakes.
Additional control of introduced prey species may be necessary as part of a long-term solution. However, this control will have little direct effect on the movements or survival of snakes in the short term. Modifying habitat in cargo areas, around electrical transistors, and outside wildlife refuges is part of a larger overall solution but will not find success as a sole tactic. On Guam, habitat modification is teamed with active trapping, visual searches, barriers, and canine detection teams to control snake densities in some areas and eliminate them entirely from high-risk sites.
See also: Snake Proofing Your Home