Aerial Application of Acetaminophen treated Baits for Control of Brown Treesnakes

Abstract : The objective of the this Demonstration Project was to validate the use of aerial techniques to deploy acetaminophen-treated dead neonatal mice baits to reduce brown treesnake (Boiga irregularis) numbers in forested sites on Guam. Canopy landing and distance between VHF marked baits was 82 percent and 19.3 m exceeding the success metric of a 80 percent and mean distance of 17-23 m, respectively. The success metric of a 80 percent reduction in bait take rate of VHF marked baits within 4 drops was achieved on the HMU site but not the MSA site (73 percent reduction). Success metrics of maintaining bait take rates below 30 percent on both the HMU and MSA for 12 and 4 weeks respectively, were achieved. Indices of snake abundance on the HMU and MSA drop location were significantly less than the reference site for all bait drop periods. A total of 5 rats (Rattus spp.) were captured in 2,772 total trap nights of sampling on all 3 locations, indicating no compensatory increase in rodent numbers. Only two non-targets (2 percent) were recovered during the 16 month field phase. The demonstration indicates that this technology can be successfully used to control brown tree snakes over large areas. Further refinement of the technology such as automation of bait delivery could provide significant cost savings in operational deployment at larger scales.