Demonstration projects were sought for innovative tools, attractants, methodologies, or technologies that could improve the efficiency of Brown Tree Snake (Boiga irregularis) (BTS) trapping and removal on the island of Guam and similar locations. Labor intensive trapping methods which require employing live baits have proven effective but are limited. There was a critical need for additional trapping and/or killing devices that would remove additional snakes of all size classes and have a better attract/capture/kill ratio. Devices did not need to capture BTS alive, since captured snakes are euthanized; however, devices should not kill snakes in a manner that would be determined as unacceptably inhumane. Proposed systems should have posed a minimum risk to human health and safety, improved the rate at which trap encounter by the BTS results in capture or morbidity, be ruggedized for outdoor use, possess low maintenance requirements, and be inexpensive to produce.
Proposed devices should have been optimized for one of two basic application scenarios: (1) High BTS density scenario where the goal is to rapidly reduce the numbers of snakes in an area. In this scenario, designers may assume that the devices will be serviced by personnel on a regular basis with the result that live lures may be maintained and the removal of live snakes feasible. Nonetheless, ease of use and frequency of maintenance will remain an important criteria. (2) Low BTS density scenario where snakes have been consistently removed and are known to be at low densities, where incipient snake populations are suspected, or where risk of accidental snake arrival is high. In the low density scenario, “sentinel devices” that require low maintenance but result in the capture or death of any snake encountering the device is optimal. Personnel in the low density scenario should not need to frequently visit the devices and, as a result, live lures or live snake capture may not be suitable.
Live animals (e.g. small rodent or avian species) may be used as lures to draw snakes to the device for capture or removal; however, no live lure shall be allowed to be harmed or consumed by a snake. Humanely euthanized rodents or avian species may be used as lures or as baits to be ingested by snakes. Systems using artificial lures or baits may also be proposed. Traditional control tools rely on foraging snakes that attempt to feed on a lure or bait. However, these devices are less effective when BTS find alternative prey abundant, have recently fed, or are otherwise in non- feeding behavioral states. Proposals for systems that remove snakes that are not actively foraging or are in prey-rich environments will receive strong consideration. To date, research has failed to identify artificial lures or baits that are as effective as a live mouse lure or a dead mouse bait. Because of their efficacy as lures and relative ease of maintenance, domesticated mouse strains are the primary lure for BTS traps. However, recent research demonstrated that some BTS that could not be captured in traps with live mouse lures were caught in traps with live avian lures. Also, BTS with a history of feeding on avian species are known to be less likely to respond to mouse lures. As a result, preference will be given to live lure designs that provide both ease of 2 maintenance and are humane to both rodent or avian lures (i.e., adequately sized lure chambers with ventilation, shade, and drainage, etc.). Survival of live lures will be a performance criterion when using live baits, so they must be protected from predation.
Lethal or nonlethal methods for BTS removal may be proposed. Live capture of BTS is desirable for research purposes, so that marked individuals could be re-released unharmed, followed in telemetry studies, or be used in cage or laboratory experiments. Snakes captured in live traps must be removed within no more than seven days to prevent inhumane death by exposure or dehydration. For operational purposes, however, all snakes removed from live traps will be euthanized. Lethal removal devices, or ‘kill traps’ must be designed to achieve a quick, reliable, and relatively humane death. Because of the labor demands for removal of live snakes from traps, an instantaneous kill device may be more suitable for low-density/low-maintenance application scenarios. Because BTS carcasses degrade within a few days or might be scavenged, an ideal kill device would incorporate some means of recording kills and verifying that it was a BTS that the engaged the device. Systems with the ability to self-report or requiring infrequent visits are preferred. All efforts must comply with the Animal Welfare Act.
Dead bait systems currently in use are well understood and optimized for simplicity, so their modification is not being sought in this call for proposals. Separately, an artificial bait development effort is underway to extend useful life of the DNM bait so proposals on this topic are not requested. Developers, however, remain free to propose artificial bait and live bait systems. Proposed systems should minimize nontarget by-catch such as coconut crabs (Birgus latro) and rats (Rattus spp.) to the extent possible.
Funded projects will appear below as project overviews are posted to the website.
Proposers should demonstrate an understanding of the biology and behavior of BTS, the objectives of BTS control, and an awareness of the control tools currently in use. Proposals should explicitly describe the proposed device and explain the concept of operation of the proposed device within the current control framework. Operationally, a continuum exists between scenarios where BTS densities grade from high to low and the potential cost of failure to capture or kill an individual snake also grades from low to high (e.g., forest habitat where no snake suppression has yet occurred; habitat surrounding cargo ports receiving sustained snake removal activities; inside cargo terminals in BTS area; inside cargo terminals on currently snake-free islands; habitat surrounding cargo terminals on snake-free islands; and natural areas within presumably snake-free habitat). Ideally, novel devices could be flexibly applied across this continuum; however, devices specifically targeted to a particular scenario will be considered. Devices will be demonstrated in a field environment and evaluated by qualified BTS research or management agencies using the trap evaluation criteria outlined by Engeman and Vice (2000)1 modified to include attractions, captures, and escapes per unit effort (e.g., trap night), size distribution, cost, practicality, humaneness, and information content. Evaluations will be conducted in head-to-head comparison trials with current tools, novel designs by federal research agencies (e.g., U.S. Geological Survey and USDA Wildlife Services), and other respondents to this Topic Area.
The ESTCP Resource Conservation and Resiliency Program Area supports the DoD mission by demonstrating and validating innovative and cost-effective technologies that enhance DoD capabilities that rely on training lands, cantonment areas, test stands, and many other types of installation facilities. This call for proposal seeks to provide new, cost-effective, and efficient tools for controlling the BTS.
1 Engeman, R. M., and D. S. Vice. 2000. Standardizing the evaluation of brown tree snake trap designs. Integrated Pest Management Reviews 5:205-212.