State officials today declared Lehua island rat-free following years of eradication efforts.
The rats, an invasive species, wreaked havoc on the state seabird sanctuary for decades by preying on the eggs and chicks of native birds.
In 2017, the state Department of Land and Natural Resources, along with numerous federal agencies, including the U.S. Fish and Wildlife Service, nonprofit Island Conservation, and owners of Niihau, joined forces to launch a new program, using lessons learned from past attempts.
“After extensive on-island monitoring, we’re 99.99% certain there are no more rats on Lehua, which builds on the successful removal of invasive herbivorous rabbits, and secures a future for Hawai’i’s wildlife and ecosystems,” said Sheri S. Mann, the Kauai branch manager for the DLNR Division of Forestry and Wildlife, in a news release.
Rabbits, also invasive, were eradicated from the crescent-shaped island about 19 miles southwest of Kauai in 2006, but getting rid of the rats proved more difficult.
The new rat control program in 2017 involved the drop of rat bait pellets containing the rodenticide, diphacinone, which sparked community concerns over adverse impacts to the surrounding waters and other wildlife.
Officials, however, said monitoring showed no negative impacts on the surrounding environment.
It took persistence and effort, and a few rats were still present a year later, as was evident in early 2018, when a rapid assessment team headed to the islet to investigate two rodents seen via motion-detecting field cameras.
Patty Baio of Island Conservation said after “mop-up efforts,” rats have not been detected on the island for over two years.
“April 2021 marks the one year anniversary since all rat-control treatments were removed from the island, adding to the data that allows us to declare Lehua rat-free,” she said.
A Hawaiian blessing by kumu Sabra Kauka was held in February to celebrate this milestone. With Lehua now rat-free, officials are looking forward to ecosystem restoration projects for birds as well as native plants.
Lehua is home to at least 17 seabird species, many of which are threatened, including red-footed boobies and Laysan albatross. The partners hope Lehua might host the endangered Newell’s shearwater, which has attempted to nest on the island without success due to rat predation.
The National Tropical Botanical Garden hopes to restore some of the 14 native plants at Lehua.
“If you restore the ecosystem, the birds will come,” said NTBG botanist Mike DeMotta. “The birds have been coming there long before men were on these islands. It’s an ahupuaa system. Restoring the ecosystem generally will not only be a benefit to the birds, but also any other organisms that are native there.”