Leap Frogs Jump into Neyland Stadium

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Granny freaks out when a frog jumps on her...

Grab your earplugs. Invasive coqui frogs gain foothold in California
Jun 8, 2017 - I can remember when the nighttime sounds of forests on the Big Island in Hawaii were filled only with the unique songs of native insects. Having studied native Hawaiian crickets for nearly three decades I’ve become familiar with the deep, cow-bell pulses of the Hawaiian tree cricket and the soft, sleigh-bell pulses of Uhini iki, the Hawaiian swordtail cricket. Today, they can barely be heard.

In the past few years, a population explosion of the invasive coqui frog (Eleutherodactylus coqui) has transformed the acoustic landscape of Big Island forests into a monotonous din, masking these native songs. Tens of thousands of amphibian voices, calling “ko-keee, ko-keee, ko-keee,” mask the songs of native endemics. So dense and widespread are the populations on the island that state officials have deemed the goal of permanent removal unfeasible there, focusing instead on eradication efforts for the remaining islands where the coqui has yet to deeply establish itself. Now the coqui has arrived in California. With few, and relatively small infestations, California should act immediately to eradicate this destructive invasive species. The coqui may look innocent, and even sound sweet to some, but its brief history in Hawaii tells a tragic story of how delayed action can have devastating consequences for biodiversity and human well-being.

The coqui frog may look innocent, and even sound sweet to some, but its brief history in Hawaii tells a tragic story of how delayed action can have devastating consequences for biodiversity and human well-being.

Although native to Puerto Rico, the coqui invaded vulnerable island habitats by hitching rides on commercial nursery plants. In Hawaii, home to thousands of endemic species, the coqui has had catastrophic impact following its introduction in the late 1980s. Unlike in their native range, coqui have achieved astonishing densities, often as high as 20,000 frogs per hectare (or 2 frogs per square meter), and sometimes over four times that number. These high densities likely arise because the frogs have escaped their natural predators and diseases, factors that regulate coqui numbers in Puerto Rico. The coqui is a predator itself, and its high numbers are bad news for native Hawaiian arthropod species, which the frogs consume with voracious appetites. Each frog consumes about eight prey animals per day, and thus, in that one square meter, on any given night, a loss of between thirty and seventy invertebrates can be expected. To put this threat on a human scale, such a density would equate to approximately 20 Tyrannosaurus rex’s per square kilometer. Admittedly, a T. rex might eat just one human per day; nevertheless, we wouldn’t stand a chance.

For the Big Island’s endemic arthropod species, this analogy suggests a grim future—and sadly, it is more than just a suggestion. In the last decade, frog populations have steadily expanded upslope from Hilo toward the Kilauea summit, such that now the night-time acoustic landscape is filled with a coqui cacophony, revealing massive populations of frogs. As recently as five years ago, native cricket numbers were healthy on Kilauea’s northeast slope. Further surveys are urgently needed, but in the vicinity of Glenwood, where there once were hundreds of thousands of crickets, they are now completely gone. And what of the other tiny forest creatures that do not reveal their losses so readily through the disappearance of sound? One must conclude that they too have been vacuumed up by the voracious coqui.

Common Coqui (Eleutherodactylus coqui) is a small tree frog averaging 1-2 inches in length. They are classified as an invasive species in California.

There are also well-known human impacts. Coqui are loud, disturbing residents’ sleep, eliciting visitor complaints at hotels and resorts, and depressing real estate values in infested areas on the Big Island. In addition, Hawaiian nurseries have repeatedly exported frog-infested ornamental plants, only to suffer economic loss when their shipments are destroyed or returned. For the Big Island’s endemic arthropod species, this analogy suggests a grim future—and sadly, it is more than just a suggestion. In the last decade, frog populations have steadily expanded upslope from Hilo toward the Kilauea summit, such that now the night-time acoustic landscape is filled with a coqui cacophony, revealing massive populations of frogs. As recently as five years ago, native cricket numbers were healthy on Kilauea’s northeast slope. Further surveys are urgently needed, but in the vicinity of Glenwood, where there once were hundreds of thousands of crickets, they are now completely gone. And what of the other tiny forest creatures that do not reveal their losses so readily through the disappearance of sound? One must conclude that they too have been vacuumed up by the voracious coqui.

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