Lehua Island: Past & Future

Archaeological surveys suggest that Hawaiians likely visited Lehua for ceremonial and fishing activities but did not live there. A 2009 archaeological report by DLNR documented a number of ahu on the island. The name of the summit is Kaunuakalā (alter of the sun), suggesting potential religious use. Early visitors to Lehua likely encountered plentiful seabirds, including albatross, boobies, and shearwaters.

Photo: An ahu on the eastern arm of Lehua, taken from the DLNR archaeological inventory report of Lehua, 2009

The August 27, 1856 edition of Ka Hae Hawai’i reports that the king (presumably King Kamehameha IV, based on the date) sailed from Waimea, Kaua’i to Ni’ihau, Ka’ula, and Lehua. On Lehua, the newspaper notes: “he nui ka ʻiole kahiki ma laila, ma ka ʻōlelo haole rabbits,” or, “there are many foreign rodents there, which in English are called rabbits” (translation via Puakea Nogelmeier, and Awaiaulu). Pacific rats were likely also on the island at this time. The full account of the royal visit can be found in the original  8/27/1856 Ka Hae Hawai’i via the Papakilo Database  managed by the Office of Hawaiian Affairs.  The translated version  is available on the DLNR website courtesy of Awaiaulu and Puakea Nogelmeier.

In 1928, Territory of Hawaiʻi and US government set aside the island for the purposes of establishing a lighthouse near its peak. In 1931 the US Lighthouse Corps (which later was made part of the US Coast Guard) took responsibility of the island and installed a gas-powered lighthouse at the summit. The lighthouse was later replaced by a solar-powered beacon. The DLNR archaeological report notes that a 1931 botanical survey by Edward Caum documented invasive plants on the island including cacti and lantana, though those species appear to have disappeared by the 1960s.

Photo: Lighthouse construction crew on Lehua, 1931 (Originally from Dean 1989, taken from DLNR archaeological inventory report, 2009)

Periodic visits to Lehua during the mid-1900s likely provided opportunities for invasive species to arrive on the island. Invasive buffelgrass became widespread on the island, and rats and rabbits continued to prey on seabirds, their eggs, and native plants.

Photo: a rat eating a bird egg (Natalia Tangalin, National Tropical Botanical Garden)

State, federal, and private partners came together in the early ‘00s to develop a restoration strategy for Lehua, with the eventual goal of restoring the island’s native bird and plant communities. The first step to recreating a refuge for native species was to remove invasive rabbits from the island, which presented a large threat to the island's vegetation and other wildlife. Working with the non-profit Island Conservation, Lehua was free of rabbits in 2006.

Photo: A rabbit on Lehua (Eric Vanderwerf, USFWS)

With rabbits off the island, the only remaining mammals on Lehua were rats. A partnership of the US Fish and Wildlife Service and DLNR attempted to remove rats from Lehua in 2009 using aerial baiting. Unfortunately, not all rats were removed from the island. The remaining rats quickly repopulated Lehua, continuing to threaten the island’s birds and native vegetation.

Photo: the rat seen here is wearing a tracking collar as part of a study on rat movements on Lehua. (Mele Khalsa, Island Conservation)

Island Conservation, the nonprofit that assisted with rabbit removal in 2006, conducted a feasibility study of rat removal from Lehua in 2012, using lessons learned from the 2009 attempt. A Lehua steering committee formed to explore the planning for a second attempt to remove rats from the island.

Photo: Restoration partners on Lehua (DLNR)

A key component of the new Lehua Island Ecosystem Restoration Project was the development of a broad partnership with DLNR, USFWS, Island Conservation, National Tropical Botanical Garden, the US Coast Guard, USDA, and more. Critically, the owners and residents of Ni’ihau engaged with the steering committee starting around 2014, sharing their mana’o about Lehua and their experience following the failed attempt to remove rats in 2009. These lessons and the continued engagement of the owners and residents of Ni’ihau became keystones of the project moving forward.

Photo: Niʻihau as seen from Lehua (Kenneth R Wood, National Tropical Botanical Garden)

To better understand how rat bait would interact with Lehua’s ecosystem, project partners conducted a trial run of bait application to the island in 2015 using non-toxic bait and a fluorescent dye. In the years since the 2009 attempt, Bell Labs had developed a new bait matrix for rats that used new flavors. The 2015 trial run showed the partners that the new bait was more attractive to rats but should have minimal-to-no impact on other species on the island.

Photo: Trial run of non-toxic bait (DLNR)

After years of work on community engagement, planning, and fundraising, the Lehua restoration project was ready to move forward. In the dry months of late summer (when other food is scarce and rats would be most likely to take the bait), the partners conducted three aerial applications of the new bait product. Agency partners, nonprofits, the owners and residents of Niʻihau worked side by side to ensure the project went as smoothly as possible.  Information and answers to frequently asked questions about the project's development and operation are provided on the DLNR website.  The US Department of Agriculture's National Wildlife Research Center conducted environmental monitoring before and after the project, including samples taken from the intertidal zone and nearshore marine environment and showed that environmental impacts were limited and short-term. You can read t he DLNR news release on the final USDA monitoring report  or  the USDA monitoring report itself .

Video: Lehua from above (Mele Khalsa, Island Conservation)

The application of bait in August and September 2017 was followed by intense monitoring for rats on Lehua using tracking tunnels, traps, and motion cameras. The population of rats on Lehua plummeted, as expected, but photos collected from the motion cameras showed photos of a very small number of rats in October-December of 2017. DLNR and Island Conservation dispatched a response team to the island, and the partners came together once more to discuss a plan for increased monitoring and continued spot-treatments of areas where rats were detected. Over the course of 2018, a number of photos showed rats, and the team adapted its response as rat sightings were recorded. The last photo of a rat on Lehua was taken by a motion camera in December 2018

Intense monitoring for rats continued throughout 2019 and 2020. Camera cards were checked regularly, and crews visiting the island looked for signs of rats eating birds or their eggs. Thankfully, no rats were detected on Lehua in 2019 or in 2020.  During this time, Island Conservation continued developing a model to determine how much time without a rat sighting would need to pass before we could say, with statistical confidence, that no rats remained on the island. As time passed and the group became more confident that the rats were truly gone, the project entered its final stages of monitoring: all bait boxes were removed from the island in April 2020.

Photo: Partners on Lehua (Tom Green, Scuba Tom Galleries)

April 2021 marks the project partners’ declaration of success. A full year has passed with no bait boxes on the island, and no rats have been documented on the island since December 2018, nearly two and a half years ago. We can now say, with a very high level of confidence, that Lehua is rat-free. In early 2021, kumu Sabra Kakau visited Lehua to provide a blessing. With rabbits and rats finally removed from the island, Lehua’s native birds and plants can return and thrive.

Photo: Kumu Sabra Kakau on Lehua (DLNR)

Since 2017, the number of birds on Lehua has increased. Species that weren’t seen on the island prior to the removal of rats have come back to nest on Lehua’s high, rocky perches. The island’s inhabitants include Newell’s shearwater, wedge-tailed shearwaters, brown boobies, red-footed boobies, albatross, and red-tailed tropic birds. Lehua is anticipated to be an even more important home for birds in the future, as it is a "high island" with elevation that should provide continued habitat as climate changes.

Video: A red-footed booby on Lehua (Mele Khalsa, Island Conservation)