In Hawaii, an Urge to Croak Some Frogs

You could call it “The Invasion of the Alien Frogs.” But this is no science fiction movie.

Tiny Caribbean frogs with a chirp as intense as a lawn mower’s roar have infiltrated the Hawaiian Islands, establishing clamorous colonies that are robbing some residents of sleep. The frogs apparently hitchhiked here hidden in nursery plants a few years ago and found Hawaii an ideal habitat.

In this rural town 20 miles inland from Honolulu, Gail Souza resorted to piling her family of four into one bedroom and using the drone of the air conditioner and the television to drown out the nightly chorus of frogs.

“It was a very piercing sound,” said Souza, who sought help from the state once she figured out what was causing the din. “It was like being taken from the country and being put into a big city, where you have sirens up and down constantly.”

Until now, the only weapon in the fight against the slippery brown creatures, known as coqui frogs, was to ambush them by hand, one by one. But the U.S. Environmental Protection Agency approved at the beginning of the month the state’s emergency request to zap some colonies with a lethal spray of concentrated caffeine. The colonies range from a handful of frogs to thousands.

“People come to Hawaii because of the peace and tranquillity,” said Nilton Matayoshi, chief of the Plant Pest Control Branch of the state Department of Agriculture. “We’re worried that this little frog will destroy that.”

In recent months, Matayoshi has been moonlighting as a “frog buster.” He waits until nightfall, then straps a flashlight to his forehead, grabs a scoop net and jar, and trudges through backyards, thickets and even plant shops. His elusive prey hides in leaf litter during the day, then leaps onto tree perches at night to “sing,” which makes them easier to track down.

Thanks to volunteers like Matayoshi, the two coqui colonies on this island have been brought under control, so Souza and her neighbors can sleep easily--for the moment.

But the Big Island is another story. More than 200 Caribbean frog colonies have been located there, up from just half a dozen in 1997, according to Earl Campbell, project leader at the U.S. Department of Agriculture’s National Wildlife Research Center in Hilo. (Those figures include a second, smaller species that is much quieter than the coqui.) Coqui choruses have driven some Big Island residents to use sleeping pills.

On Maui, the frogs have aggravated rural dwellers and even turned up in landscaping around two resort hotels on its west coast. Hotel managers quickly captured as many as they could find. So far Kauai, Molokai and Lanai appear relatively unaffected.

Slightly bigger than a quarter, the coqui gets its name from the two-pitched call, “co-KEE,” made by lusty males at night to attract females. A coqui’s call has been recorded as loud as 100 decibels from a distance of half a yard, according to the journal Herpetologica. That’s the same intensity as the sound of a lawn mower or an 18-wheeler truck.

Of course, the distinction between music and noise is often in the ear of the beholder. It all depends on what you’re used to.

“It sounds like a bird. It’s not an unpleasant sound,” said Lyle Wong, administrator for the Plant Industry Division of the state Department of Agriculture. “But when you have many, many, many male frogs hot to trot with female frogs, it’s really a racket.”

In their native Puerto Rico, the little creatures are cherished, and their nighttime calls are likened to a lullaby. When word reached the Caribbean that Hawaii was trying to wipe out its coqui population, some folks there were offended. Puerto Rico’s congressional member, U.S. Rep. Anibal Acevedo-Vila, lodged a protest with the U.S. Department of Agriculture last month, calling the coqui “a national symbol of Puerto Rico” and seeking a halt to “any eradication program.”

Authorities here, however, argue that Hawaii’s unique and fragile environment cannot handle the frogs. Elsewhere, coqui populations are kept in check by competition from other types of frogs, lack of habitat, cold snaps, predators or disease. But the isolated Hawaiian Islands, whose ecosystem evolved without native reptiles and amphibians, lack such defenses.

“Coqui frogs do not belong in Hawaii,” Campbell said. “Like so many other plant and insect pests, these frogs may be benign where they occur naturally, but when they come to Hawaii, because we’ve never had this type of thing before, they do extremely well.”

Besides the nuisance factor, biologists are concerned that burgeoning populations of coqui frogs may wipe out some rare Hawaiian insects and compete with native birds for food. Coquis reproduce exponentially, with females laying an average of 140 eggs each year. As many as 8,000 coquis can crowd into one acre. Their sheer abundance could boost the population of predators. Although Hawaii has no snakes, a natural predator, it does have rats and mongooses.

The EPA decision allows authorized personnel to spray a concentrated caffeine solution in certain areas to kill larger frog populations. The dose is equivalent to a human drinking 110 cups of coffee, Matayoshi said.

The state also may begin treating nursery plants with hot-water drenches or caffeine to prevent further coqui dispersal.

If control efforts don’t do the trick, Hawaii residents may have to learn the Puerto Rican folk song, “El Coqui,” whose Spanish lyrics translate as follows:

“Little frog, little frog makes me happy

With his singing so lovely and sweet.

When at nighttime I lie down and listen

It’s his singing that puts me to sleep.”

To judge for yourself whether the coqui makes noise or music, you can listen to their calls at https://www.hear.org/frogs.