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By Gemma Q. Casas

SAIPAN, CNMI (Marianas Variety, Oct. 13) – Five species of frogs have been recently introduced on Guam, which scientists fear can fuel an increase in the population of brown treesnakes on Guam and the Northern Marianas.

This comes on the heels of the recent passage by the U.S. Senate of a bill to eradicate the brown treesnake on Guam and the Pacific.

As of 2002, the U.S. Geological Service reported that Guam’s snake population was estimated at one million - six times more than the human population of 154,805 then on the island.

Brown treesnakes have killed off numerous birds on Guam and disrupted the island’s ecological balance.

Nate Hawley, a biologist and herpetologist at the CNMI’s Division of Fish and Wildlife, said the five new frog species could be a new food source for the snakes. The frogs, he said, may have been accidentally sent to Guam through a shipment of ornamental plants or agricultural products.

Some of the newly discovered invasive frog species are the greenhouse frog, coqui frog, bark-in frog and the tree frog.

"They’ve all been found in Guam in the past couple of years. They were transported via ornamental plants or agricultural products," said Hawley.

"They would provide a ready food source for the snakes. So the snake population would dramatically increase with such a new food source," he added.

Last month alone, two sightings of snakes were recorded on Saipan.

But Hawley said there are no confirmed reports that the new species of frogs are in the CNMI.

Nonetheless, they are monitoring the situation in CNMI.

"We’re on the lookout (for frogs). If Guam has them, it might only be a matter of time before we (in CNMI) get them. So we have to be very aggressive with our quarantine program at the point of entry," said Hawley.

The new frogs in Guam were discovered in swampy areas in the southern part of the island.

On Sunday, Hawley led a team of men and women to educate the residents in Rota about the dangers of brown treesnakes.

Rota is a potential haven for the snakes since it has lush vegetation and plenty of birds.

"They would do very well if they got here because there’s a lot of food," Hawley said.

He stressed though that Saipan and Tinian are at greater risk because the volume of cargo that enters its seaports and airports is higher.

Thus far, only two confirmed sightings of the snakes have been recorded in Rota since 1992.

Hawley said they purposely held the information campaign during the weekend Rota fiesta because there were many people from different islands expected to come.

"Well, the Rota fiesta is a special time for the Rotanese, not only them, but the whole CNMI. The mayor puts on a great party here and we thought this was a great opportunity to come down and meet the people and pass out some of the new educational materials we have."

The DFW team brought a caged sample of a live brown tree snake to Rota.

Hawley said the division has four snakes which are used for the educational campaign and to train detector dogs.

Each snake has a transmitter so it can be tracked down if it accidentally escapes from the cages.

Hawley, who is originally from Wisconsin, said the snake’s venom is quite mild and there have been no reported deaths among humans since the reptile was introduced to the Marianas in the 1940s.

"There hasn’t been any confirmed report that a brown tree snake has killed here or anywhere.... They do have a mild venom. It does have some negative effects on the respiratory system," he said.

An average female brown treesnake can lay as many as 13 eggs. In its lifespan of six to eight years, it can reproduce more than 10 times, according to Hawley.

"(Its) average lifespan is six to eight years on Guam. But I think before, there was a lot of food so they may have lived a lot longer," said Hawley.

October 13, 2004

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