Recovery of Native Species following Rat Eradication on Mokoli‘i Island, O‘ahu, Hawai‘i.

Abstract

Rats were eradicated from Mokoli‘i, a 1.6-ha island off the east shore of O‘ahu, using snap traps, cage traps, and diphacinone bait stations. A total of 18 black rats (Rattus rattus) were caught, and 354 bait blocks were used. There was no sign of rats on the island after 27 May 2002. Wedge-tailed Shearwaters (Puffinus pacificus) nest on Mokoli‘i, but only a single chick survived during 1999–2001; the number of surviving chicks increased to 126 in 2002 and 185 in 2003. The number of intertidal invertebrates and native plants, including the endangered Carter’s panic grass (Panicum fauriei var. carteri ), also appeared to increase after rat eradication. Rats had a devastating impact on the flora and fauna of Mokoli‘i, and their eradication has allowed a dramatic recovery of native species. The majority of the labor for the eradication effort was provided by the local community, demonstrating what can be achieved with dedicated volunteers and community support.