Rat Control for the Protection of Endangered Birds, Plants, and Tree Snails on the Island of Oahu, Hawaii

Abstract

Author(s): Mosher, Stephen M.; Rohrer, Jobriath L.; Costello, Vincent; Burt, Matthew D.; Keir, Matthew; Beachy, Jane; Kawelo, H. Kapua; Mansker, Michelle | Abstract: Since 1997, the Oahu Army Natural Resource Program has been controlling rats using diphacinone rodenticide in small-scale bait station grids in combination with rat traps for the protection of one endangered forest bird species, 5 species of endangered Oahu tree snails, and 9 species of endangered plants in 2 mountain ranges on the island of Oahu. Endangered tree snail and some plant populations are protected year-round. Other plants are only protected during their flowering/fruiting season, with small-scale baiting grids in combination with rat traps; and the Oahu Elepaio is only protected during its breeding season, with small-scale bait station grids in combination with rat traps centered on territories. In May 2009, year-round rat control was initiated over a 26-ha forested management unit on Oahu with 440 snap traps. The New Zealand Department of Conservation current best practice rat kill-trapping technology is being utilized for the first time in Hawaii with this large-scale trapping effort. Rat activity within the management unit will be monitored through the use of tracking tunnels. Forest health (seed rain and seedling germination), endangered plant recruitment, endangered tree snail survival, and native invertebrate abundance will be monitored closely to determine the effectiveness of this large-scale trapping effort. The Oahu Army Natural Resource Program is working towards integrating multiple control methods (bait station grids, large-scale rat trap grids, predator-proof fencing, hand and targeted aerial application of rodenticide) over large-scale areas in an effort to determine the most effective means to control rats in Army-managed areas on Oahu.