SREL Reprint #3378

Brown tree snake (Boiga irregularis) population density and carcass locations following exposure to acetaminophen

Joshua B. Smith1, Kelsey L. Turner1,2, James C. Beasley1,2, Travis L. DeVault3,
William C. Pitt4, and Olin E. Rhodes Jr1,5

1Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, SC 29802, USA
2Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, USA
3U.S. Department of Agriculture, National Wildlife Research Center,
6100 Columbus Avenue, Sandusky, OH, USA
4Smithsonian Conservation Biology Institute, 1500 Remount Road, Front Royal, VA 22630, USA
5Odum School of Ecology, University of Georgia, Athens, GA, USA

Abstract: Mass aerial delivery of dead mouse baits treated with acetaminophen has been evaluated as a means to reduce brown tree snake (Boiga irregularis) populations over large areas, increasing the likelihood of wide-scale eradication on Guam. Given the high density of snakes in some areas of their invasive range, eradication efforts could result in a resource pulse that may influence food web dynamics and the indirect transport of acetaminophen among trophic levels. We evaluated abundance, habitat type, and snake size (i.e., age) within two study sites on Guam, a secondary limestone forest (upland) and an abandoned coconut plantation (coastal), to determine how experimentally dosing snakes with acetaminophen is likely to influence carrion availability. We found snakes trapped in 3.24 ha plots occurred in greater abundance (population size = 72.5 snakes; SE = 8.8) and were significantly larger (978.6 mm, SE = 14.9) in the coastal than in the upland site (population size = 26.9, SE = 21.5; length = 903.0 mm, SE = 15.9). Despite these differences, carcasses of snakes that died after consuming acetaminophen-laced mice (80 mg) were recovered in consistent locations between sites, with 92% located on the ground, 4% in trees, and 4% found in rock cavities at both sites. Given that most snakes were found on the ground rather than in the tree canopy, our results suggest that many poisoned snake carcasses will be accessible to a wide range of potential scavengers, possibly influencing food web dynamics and potentially contributing to indirect toxicant transfer within affected ecosystems.

Keywords: Acetaminophen; Carcass location; Brown tree snake; Indirect toxicant transfer; Scavenging

SREL Reprint #3378

Smith, J. B., K. L. Turner, J. C. Beasley, T. L. DeVault, W. C. Pitt, and O. E. Rhodes Jr. 2016. Brown tree snake (Boiga irregularis) population density and carcass locations following exposure to acetaminophen. Ecotoxicology 25(8): 1556-1562.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).