Program targets Lehua isle rats

Poisonous bait will be used to eradicate the rodents, which eat native flora and fauna

LIHUE » With the rabbits gone, state and federal wildlife officials are focusing on eradicating the rats on Lehua island.

Officials say native plants, wildlife and seabirds will be restored by ridding the non-native rats roaming Lehua, an uninhabited 290-acre, crescent-shaped island less than a mile north of Niihau.

"Rat eradication will clear the way for native species to come back to Lehua on their own or be reintroduced as part of the restoration plan," said Chris Swenson, Pacific Islands Coastal Program coordinator for the U.S. Fish and Wildlife Service.

Swenson said the Polynesian rats were first documented on Lehua in the 1930s. They eat native plants and animals, including seabirds, Swenson said.

Bait pellets containing the poison diphacinone, an anticoagulant, will be dropped over the island using a bait hopper carried under a helicopter. Diphacinone kills rodents by causing internal hemorrhaging.

This method was used in February on the Mokapu islet off Molokai.

Details of the rat eradication was provided in a draft supplemental environmental assessment released by the U.S. Fish and Wildlife Service and the state Department of Land and Natural Resources.

The agencies will hold a public meeting July 24 on Kauai to gather public comment on the draft assessment, which supplements a final assessment that was approved in September 2005.

The draft says the eradication will occur from December through February, when the rat population and native nontarget migratory species present on Lehua are in the lowest numbers.

If the application of the bait pellets happens after the hatching of albatross chicks, all pellets within six feet of each nest will be manually removed so the chicks cannot accidentally eat the pellets.

Also, aerial application is found to be more effective in the distribution of the bait pellets over the rough terrain of the island, and results in fewer disturbances to native seabirds and monk seals.

The draft assessment is needed to complete the complete the Lehua Island Ecosystem Restoration Project.

Rabbits were successfully removed from Lehua in 2005-06 through hunting efforts. They were considered a threat to the plants.

"We had to give that time to make sure they were in fact gone, then we can concentrate on the rats," said Scott Fritz, DLNR's wildlife program manager. "Once the rabbits and rats are removed, we expect the vegetation to recover quickly on its own."