Draft Environmental Assessment for Rat Eradication within the Hiʻi Predator-Proof Fence on Lānaʻi

Project Summary 

The U.S. Fish and Wildlife Service (Service) is proposing to eradicate rats (Rattus spp.) from the recently completed Hiʻi predator-proof fenced unit, built to protect ʻuaʻu (Hawaiian petrel, Pterodroma sandwichensis) habitat on Lānaʻi, through the use of a targeted aerial application of diphacinone. This effort is consistent with the statutory missions and responsibilities of the Service.  

ʻUaʻu were listed as endangered under the Endangered Species Act in 1967. ‘Ua‘u exhibit strong natal philopatry (tendency to return to birth site to breed) and high nest-site fidelity. These behavioral traits, along with a protracted nesting period and ground nesting habitat, result in great vulnerability to predation by introduced mammals at the breeding colonies.  

The purpose of this rat eradication effort is to improve the survival rate of endangered ʻuaʻu on Lānaʻi by eradicating rats from within the Hiʻi predator-proof fenced unit. Monitoring of ʻuaʻu on Lānaʻi indicate that the Lānaʻi Hale supports one of the densest nesting concentrations in the Hawaiian Islands.  The project is further supported by the clear evidence that depredation by rats is the primary threat to ʻuaʻu on Lānaʻi. The need for this Proposed Action is to address predation by rats, the primary threat to ʻuaʻu on Lānaʻi. Aerial application is considered the most efficient and effective method to achieve rat eradication within the project area.  

To comply with obligations under the National Environmental Policy Act (NEPA), the Service is preparing an environmental assessment (EA) to address the impacts of the Service’s purchase and aerial application of diphacinone within a fenced unit on private land important for the continued survival of the endangered ʻuaʻu. This EA provides background information on the aerial application of diphacinone, outlines the proposed action, potential impacts, considered alternatives, and strategies to avoid and minimize potential negative effects of the proposed rat eradication efforts within the project area on Lānaʻi. 

Comment Period - How to Provide Comments 

The draft environmental assessment will be available for public comment from July 26 to Sept 3, 2023. The document is available below.

• Comments can be submitted in multiple ways: 

• Via email to pifwo_admin@fws.gov with Subject: “Draft EA Hi‘i Predator-Proof Fence on Lānaʻi”  

• Via mail, postmarked by Sept 3, 2023, to: U.S. Fish and Wildlife Service, Pacific Islands Fish and Wildlife Office, 300 Ala Moana Blvd., Room 3-122, Honolulu, HI 9685