Drones to curb invasive coqui found at higher elevations on Oʻahu

Invasive coqui frogs have been found at higher elevations of the Koʻolau Mountains than previous infestations reported on the island of Oʻahu. In June, crews with the state Department of Agriculture confirmed the findings on 13 acres of forest located roughly 200 meters below the summit of Kuliʻouʻou Ridge Trail on the leeward side of the mountains.

The infestation was initially reported by a citizen, and later confirmed thorugh surveys of the area by the DLNR Division of Forestry and Wildlife, and the Oʻahu Invasive Species Committee.

The new infestation site presents several logistical challenges for response efforts. The remote location, steep slopes inaccessible by foot and highly variable weather, prevent crews from using a traditional hose-based spray system to deliver a non-toxic citric food additive mixed with water used to control the frogs.

DOFAW field staffers are planning to use drone technology to apply the citric treatment at these higher elevations. Aloha ʻĀina Drones, a Hilo-based operation specializing in agricultural and conservation drone applications, is contracted to do the work.

In Hawaiʻi, coqui reach densities much higher than in their native Puerto Rico. Their loud calls disturb residents and the invasive frogs have large impacts on local insect communities. Coqui are now widespread on Hawaiʻi Island and are targets of control efforts on Kauaʻi, Oʻahu and Maui.

To date, the frogs have not been detected at lower elevations on the leeward side of the Kuliʻouʻou Mountains. Kuliʻouʻou residents and hikers on the Kuliʻouʻou Ridge Trail and Kuliʻouʻou Valley Trail are encouraged to listen for frog calls. Pest reports can be submitted online at 643pest.org or by calling the 643-PEST telephone hotline. Staff from DOFAW and OISC will be present at the Oct. 2, 2024 meeting of the Kuliʻouʻou Neighborhood Board to share information and answer questions about this project.