Not every menace looks menacing. Take the coqui frog: at a glance it’s the very definition of unassuming—small, delicate, even cute. But don’t be fooled. The coqui is a very real threat, an invasive species that’s taken hold in our remote island chain with consequences ranging from disruptive to potentially dire. The largest population is on the Big Island, but coqui have spread to Kauai, Oahu and Maui.
So who’s fighting this invasion? Locally, it’s the Maui Invasive Species Committee (MISC), one of several island-based organizations that offer education, public outreach and, most essentially, work to control and eliminate invasive species, a task that’s often too big for already-overwhelmed public agencies to tackle.
Recently, we checked in with Abe Vandenberg, a Maui musician who has spent five-and-a-half years on the front lines as a member of MISC’s “frog crew.”
Why is the coqui such a dangerous invasive species?
Coqui populations on the Big Island have reached densities of at least 20,000 frogs per acre, with over 50,000 acres affected. The same thing can happen here, so the threat is pretty serious. With even small populations, coqui have impacted tourism, agricultural and real estate markets, and affected residents’ quality of life. In greater abundance, populations have resulted in negative environmental impacts such as reductions in Hawaii’s invertebrate populations, which make up most of Hawaii’s endemic fauna. The coqui frog may also serve as a food source for devastating bird predators like the brown tree snake.
As for the quality of life issue, each adult calling frog has a volume around 90 decibels. Up close it’s absolutely ear-splitting and at a distance, 20,000 frogs an acre can be maddening. In Maliko Gulch, where the last large population is left on Maui, I find it to be literally disorienting. Talk to people who live in Hilo or Puna on the Big Island and you’ll hear the same, almost cliché nightly stories of not being able to sleep peacefully, or talk without shouting on the phone. The frogs can be heard on the other end of the phone line and even while driving with the windows up and the radio on.
I have a firm belief that after a couple of nights without sleep, anyone’s pleasant thoughts about coqui frogs would disappear along with their sweet dreams.
Do you ever go to the Big Island to deal with the problem there? How about other islands?
Our work is mostly Maui-centric, but we do work closely with other invasive species programs on the Big Island, Molokai, Oahu and Kauai. However, we rarely go to other islands to deal with their problems. I’ve been to the Big Island to see the extent of the coqui problem and it is totally overwhelming to me. Besides, why would we want to leave Maui County when there is so much to do and our County is so supportive? Over the past few years Maui County has been the most supportive of all the counties in Hawaii as far as funding for invasive species goes.
How close is Maui to being coqui-free?
Unfortunately, I would not say that Maui is coqui-free. But just having you ask the question indicates that we are headed in the right direction. Just a few short years ago coqui were much more widespread. In order to keep Maui coqui-free, we’ve started a “coqui-free” certification program for nurseries and plant-related businesses. The program is designed to prevent the spread of coqui frogs via the plant trade, which is the most common means of dispersal. The program requires participant businesses to follow codes of conduct that minimize the possibility of new introductions—[things like] night-time inspections by trained staff [and] purchasing plant stock from other coqui-free businesses. Thirty of 35 interested businesses on Maui have met the standards and are now recognized by MISC as coqui-free. Ideally if people see that a business is designated as coqui-free, they can feel confident that they will not be moving coqui frogs to their neighborhood or place of business. [More info about the program can be found at coquifreemaui.org.]
Describe some of the methods you use. Are there any that have adverse effects on the surrounding environment? How do you mitigate those risks?
We have all kinds of creative ways to control coqui frogs. The old fashioned hand-capture works pretty well for individual frogs. For larger populations, we spray a 12 percent solution of citric acid, which is the same stuff that’s in soda and a lot of the food we all eat. Citric is great because it breaks down quickly in the environment and doesn’t affect much as far as non-target species. When spraying by hand, we use hoses, pumps and backpack sprayers to apply the citric acid solution. We also have large-volume sprinklers that can spray citric acid a couple hundred feet. Helicopters also have their place in areas that are inaccessible. Each of these methods has its benefits, drawbacks and applicability, which is nice because we can use the method that is most effective for the situation we’re faced with. The bottom line is that citric acid is a blessing because it works and is relatively harmless to us and the environment. My concern for the health of the environment is why I started doing this kind of work in the first place.
How do you respond to people who say that eradicating invasive species is futile and even cruel, and that humans are the worst invasive species of all?
Context is extremely important when discussing invasive species. I typically try to relay the circumstances that surround the species of concern to people in order to provide some reasonable basis for our actions. For example, discussing where a species is part of a functional ecosystem and where it is not, impacts the species has on native ecosystems and biological differences the species may have in a non-native environment—if it reproduces faster and more often, spreads like crazy, doesn’t have any natural enemies—are starting points for a good response. Another good tactic is to use examples from other, similar environments to build our case. Take Miconia. It can scarcely be found in areas of Guatemala where it’s from, yet has taken over most of Tahiti’s native forests and caused landslides there. Who wants to deal with something like that? Therefore, we should control it while we can.
As far as people are concerned, I believe that we are inseparable from our environment and have a responsibility to take care of it to the best of our ability. To take care of the environment is to take care of ourselves.
How optimistic are you that coqui can be contained or eliminated statewide?
I believe that with consistent vigilance coqui can be eliminated from Kauai and Oahu, where there are very small pockets of frogs. On the Big Island there are efforts to protect high value areas, but in the long run people aren’t going to get rid of coqui given the current control options. Unfortunately, it’s a case of too little, too late. On Maui we started at a crucial time. If we had waited any longer we’d be in big trouble. At this point, I’m confident that by sticking with it coqui can be eliminated. We’ve achieved great success at 11 of the 17 known population centers on the island, where no coqui have been heard in over a year. Five of the other known population centers are on track for complete removal and only one large population remains—Maliko Gulch. The Maliko population is spread over a four-mile area and throughout a steep-sided, densely vegetated drainage on the north shore. Control work has begun in Maliko, [but] it will take a while for the population to be noticeably reduced. As with other sites where we’ve already had success, the key is persistence and perseverance. Without those two traits nothing can be accomplished.
However, even if we eliminate every coqui frog that is currently on Maui, there has to be continuous vigilance due to reintroduction. The threat is always there. I say that to be realistic, not alarmist. If after all my experience I felt this wasn’t a real problem and that we couldn’t deal with it given proper support and resources, I would find something better to do with my time. Life is too short to waste time on things I don’t believe in.