Chirpfest
A coqui pow-wow

by Barbara Fahs

Coqui frog experts gathered in Hilo Feb. 7-9 for the First International Conference on the Coqui Frog. Sponsored by the Hawai'i Island Coqui Frog Working Group, scientists came from as far as Pennsylvania and Austraila. Other problematic amphibians were also discussed, such as the Cuban tree frog and the highly invasive Bufo, or cane toad. UH-Hilo researchers and other local experts presented findings about population density in Hawaiian forests, skin hydration, sound levels, parasites that might be helpful in controlling their numbers, and tech-niques for controlling this noisy pest.
Karen Gundersen of the Kaua'i Invasive Species Committee reported that early detection of a coqui invasion near Lawai resulted in containment after the formation of a Coqui Frog Working Group in 2005. Land was cleared, traps set, and lime and citric acid were sprayed, resulting in Kauai'i's single infestation being nearly eliminated. Dr. William Mautz of UH-Hilo summed it up by saying, "rapid response to new invasive species is key.... These synergistic conversations will make a difference in our ability to manage this frog and other invasive species."
Hawai'i isn't
Puerto Rico
Comparisons of the coqui in its native Puerto Rico are helpful in learning about this creature in Hawai'i and understanding its habits so we can better control it here. Forests in Puerto Rico are very different from those here, because Hawai'i has far more "understory plants," or low shrubs that cover the forest floor under large trees. Such an understory provides perfect daytime cover for the coqui. By keeping areas cleared of this foliage, we can better keep the frog away from our homes. "Choke shrubs, choke coquis," observed one participant.
Since most of the understory in Hawai'i consists of invasive plants, this is an important practice for homeowners to attend to-it keeps the non-native plants at bay AND prevents potential invasions of coqui frogs. The leaf litter created by some invasive species such as trumpet trees (Cecropia obtusifolia) provides excellent habitat for the frogs, so keeping your yard raked is a good way to discourage the frogs. However, it's not necessary to remove large trees-they do not seem to encourage coqui colonies as much as the low shrubs and leaf litter.
Homeowners can also fill cracks in a'a lava with cinder. The practice of "ripping" your lava, which essentially turns a pahoehoe into an a'a, only encourages coquis by providing a habitat for them.
The Invasive Species Committee members agreed that interisland cooperation is essential if we are to prevent the spread of this pest from infested areas to islands such as Moloka'i and Lana'i, which remain coqui-free.
The conference did not focus on control or eradication: It included primarily reports of the scientific research conducted by the world's experts. Knowledge is power, and if we can learn more about coqui frogs and other bothersome invaders, we may learn to control them without the use of citric acid, lime, or other types of chemical controls.
Chemical controls
David P. Davis, Ph.D, of Ono Loa Orchards in Kurtistown, presented a poster about a new product he has developed that is effective in controlling the frogs. ACS-P is made from Acidic calcium sulfate-a nontoxic agent approved for use by the Food and Drug Administration and the USDA. It is generally regarded as safe (GRAS) and it is effective because of its high concentration of hydrogen ions and its low corrosive effect on human skin. But when applied to a coqui frog, it is quickly absorbed and lethal. Dr. Davis believes that the EPA might approve ACS-P for emergency use as a "minimal risk pesticide for use against coqui frogs." For more information, e-mail him at coquicontrol@gmail.com.
Dr. Mautz concluded the conference with a Hawaiian expression: "I kahiki no ka hao, o ke ki'o ana i Hawai'i nei," or "In faraway lands was the iron, in Hawai'i the rusting." In other words, certain species might be beneficial in their native lands, but when they come here they can become a nuisance. The coqui frog is not evil: it is merely taking advantage of our favorable environment.
Words of wisdom from Chinese philosopher Sun Tzu, author of the 2,300-year-old treatise The Art of War, warned, "If you know yourself but not your enemy, for every victory gained you will also suffer a defeat."
On the Web
ctahr.hawaii.edu/coqui/conf08.asp#ConferenceDescription
hear.org/starr/hiplants/images/thumbnails/html/cecropia_obtusifolia.htm
antiwar.com/pena/?articleid=9755

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