A team of wildlife officials and experts flew to Lehua Island after motion-detecting field cameras revealed the presence of two rats on the island.
Last August and September, the state, in partnership with the group Island Conservation, dropped three applications of rodenticide in order to rid the island of invasive Pacific rats.
Officials say they are voracious predators that kills eggs, chicks, and even adult native seabirds that currently breed and nest on the remote island off Niihau.
Human observations using a variety of other monitoring devices last month did not detect any sign of rodents.
However, camera cards, which had been deployed by the Kauai Endangered Seabird Recovery Project (KESRP), were reviewed after Christmas and revealed images of two rats.
“These cameras are highly effective critical early warning tools for locating any remaining rats. They did their job and we can now target areas for a swift response to hopefully deal with whatever rats remain on the islet,” said Dr. Andre Raine of KESRP.
Following the rodenticide applications, monitoring teams are scheduled to travel to the island every other month. This week’s trip is in advance of a previously planned trip in mid-January.
The team placed a total of 134 monitoring devices on Lehua, including three different types of traps. Some of the devices will be left in place; others will be re-established when monitoring teams return to the island.
Other than the two rodents caught on camera, none of the devices have detected rat presence since the rodenticide applications began.
The team will meet with project managers to assess a suite of additional treatment options, including localized hand-applied rodenticide application.
“While we are clearly disappointed to see evidence of two rats on the island, we are very lucky our partners were able to detect them. We knew from the beginning there was the possibility that a few rats could linger. Now it’s important to address this,” said Suzanne Case, chairwoman of the state Department of Land and Natural Resources.
Officials say it will take a full year after the final application to determine whether the rats have been successfully removed from the island’s ecosystem.