Ko-KEE, Ko-KEE, Ko-KEE.
As darkness falls over East Hawaii, the chorus of coqui frogs intensifies, and more of the little amphibians add their mating calls to the mix.
To some, the small invaders from Puerto Rico are a noisy nuisance, disrupting sleep, lowering property values, devaluing nursery crops and interfering with the native ecosystem. To others, the frogs’ calls are the music of the rain forest, a soothing sound from a welcome critter that gobbles up mosquitoes, flies and even fire ants.
It’s that second group that needs to be taken into account for coqui control methods to work more effectively, says a study published in the December edition of the scientific journal Biological Conservation. The article, “A social–ecological systems approach to non-native species: Habituation and its effect on management of coqui frogs in Hawaii,” found what principal researcher Emily A. Kalnicky calls an unexpected result.
“It seems there is a relationship between people’s attitudes and the number of frogs in a given area. It was the opposite of what we expected,” Kalnicky told West Hawaii Today on Friday. “People with a lot of frogs had a more positive attitude about them. … They’re beginning to tolerate the frogs. .. They’re getting used to them being there.”
Kalnicky, who researched the topic for her Ph.D. dissertation in ecology at the Department of Environment and Society and the Ecology Center, Utah State University in Logan, co-authored the Biological Conservation article with fellow researchers Mark W. Brunson and Karen H. Beard, of the Utah Agricultural Experiment Station and Ecology Center, Utah State University.
The research was conducted on Hawaii Island, but it has implications statewide, especially considering the millions the state has already spent trying to control the frogs and as residents on the more populous Oahu begin reporting more frog noise there.
“While the government’s position on the coqui does not appear to consider any potential societal or ecological benefits of coqui frogs, helping to educate people on the most effective management and why people should want to do so seems critical in achieving the government’s goals of control or eradication,” the study concludes.
Kalnicky said habituation can be viewed as either positive or negative, depending on the social-ecological system in question.
For a species with negative social-ecological effects, an initial influx of resources early could be beneficial in achieving long-term goals of control or eradication, as possible habituation could mean effort spent on changing attitudes may be less effective over time. Efforts to reduce time to habituation should include education and outreach on potential societal and/or ecological benefits, researchers said.
In the case where a non-native species is unlikely to have long-term detrimental effects on social or ecological systems, it is possible that a wait-and-see approach may be beneficial in reducing money spent attempting to control or eradicate the species, especially if habituation is likely, they said.
The state of Hawaii definitely sees the frogs as a negative.
“Habituation, meaning that people ‘get used to’ a species over time and might be less likely to consider it a nuisance, is not a relevant criteria in driving funding decisions by the interagency Hawaii Invasive Species Council,” Joshua Atwood, Department of Land and Natural Resources invasive species coordinator, said in a statement responding to questions for this report.
Atwood said coqui frogs have been designated as “injurious wildlife” by DLNR and a “pest” by the Department of Agriculture, which allows the state to control their populations.
“Those designations are based on impacts to agriculture and the environment, and would not change based on whether people are habituated to hearing the sound of coqui frogs around their home,” he said. “One factor that does drive management decisions is the likelihood of success for controlling a species in a certain area, and areas with newer, smaller colonies of coqui frog do have a higher likelihood of success for effective control.”
Studies have shown that coqui frogs harm the environment by eating invertebrates other species depend on for food, upsetting the natural balance. One of the impacts shown in a study on Hawaii Island was that coqui predation on herbivorous invertebrates alters the amount of leaf production and decomposition in forests and alters the flow of nitrogen and phosphorous through leaf litter and soils, he said.
The state doesn’t, however, appear to devote significant resources to educating the public in coqui-saturated areas about why coqui frogs should be controlled. Instead, the Big Island Invasive Species Committee concentrates its outreach and education program to work with neighborhoods that want to learn about how to manage coqui frogs in their area.
Kalnicky conducted her research in the summer of 2008 on 85 private properties in 12 communities across Hawaii Island. Researchers measured the relationship between coqui abundance, residents’ attitudes toward the coqui, their reported participation in control activities and environmental variables that affect habitat quality for the frog.
Interestingly, people who own their property had a more positive attitude about coqui frogs than renters did.
“Property owners may hold less negative attitudes because they have greater levels of attachment to their properties and therefore greater investment in staying where they live,” the researchers theorize. “They therefore may want to believe that their property value has not been lowered, thus, offsetting the undesirable consequences of coqui invasion.”
Pahoa resident Sydney Ross Singer is one of the Big Island’s most vocal coqui advocates. Singer, who holds a bachelor of science degree in biology from the University of Utah and a master’s in anthropology from Duke University, and his wife, Soma Grismaijer, have what he calls a “coqui frog sanctuary” on their lower Puna acreage.
Singer said tree frogs are becoming increasingly endangered worldwide and efforts should be made to protect them, not obliterate them. He disputes claims that the frogs are eating too many insects and competing with native wildlife.
As for the noise?
“We were anxious at first. … (People) really exaggerated how loud they are,” Singer said about his initial experience with the frogs.
Now, he finds he can’t sleep as well without hearing them. So much so, in fact, he listens to a recording of the little critters when he travels.
“The more the merrier. They create a beautiful chorus,” he said. “It helps you go to sleep. It’s so soothing.”