A Nasty Intruder Is Taking Its Toll On Guam's Nature

Posted: February 04, 1990

AGANA, Guam — It began with an anxious cry at dawn from the nursery, a sound that neither Ernest nor Yvonne Matson had ever heard from their 10-month-old son, Skyler.

Entering Skyler's room, Ernest Matson saw the baby struggling to peel a five-foot snake from his body. The snake had wrapped its tail around the youngster's neck, its body around his feet.

Matson saw a patch of blood on the crib sheet. The snake had been chewing on the boy's hand, which was covered with puncture wounds and snake saliva.

The brown tree snake - a tenacious, mean-spirited animal - had struck again.

An unwelcome intruder from the Solomon Islands since the 1940s, the brown tree snake once stalked Guam's tropical birds - until the voracious reptile virtually wiped them out by 1986, leaving the rain forests eerily quiet.

Nine species of forest birds were destroyed, including three found nowhere else in the world: the rufous fantail, the bridled white-eye and the broadbilled flycatcher.

The snake attacked farms and ranches, where it eliminated generations of chickens, rabbits and ducks by eating their young.

And now it was pushing into every urban nook and cranny on this Pacific island, creating a waking nightmare.

In 1988, 11 residents were treated for brown tree snake bites; five were youngsters. Last year, the number jumped to 31, including 10 youngsters, most of them under 3 years old. Power outages caused by snakes hitting high-tension lines have risen from 15 in 1978 to nearly 100 in 1987.

But aside from the horrors and the inconveniences posed by the snake, an underlying ecological balance may have been tipped. The eradication of the birds seems to have led to an upsurge in the population of insects and spiders.

Biologists worry that the combination of fewer birds and more insects will lead, in turn, to defoliation of plant life, and an end to the pollination that produces new plant life.

More worrisome is the spread of this ecological plague across the Pacific.

"Guam isn't just a problem anymore. Now, it's a source," said Thomas Fritts, a research biologist with the U.S. Fish and Wildlife Service, based at the Smithsonian Institution in Washington.

In October, as a military cargo plane flying from Guam to Hawaii glided toward a Honolulu runway and lowered its wheels, a brown tree snake that had hidden in the landing gear fell to the ground. The snake was killed on the spot, but the question lingered: How many have gotten through unnoticed?

The brown tree snake has been found on Wake Island and Kwajalein in the Pacific, and on Diego Garcia in the middle of the Indian Ocean, in addition to Hawaii. There have been unconfirmed reports of the snake on nearby Saipan and Pohnpei.

The snake apparently got there the same way it got here from the Solomon Islands, about 1,500 miles southeast: accidentally. It is commonly believed that the snake arrived as a stowaway aboard cargo planes that were shuttling war materiel around Pacific islands after World War II.

On the Solomons, the birds and snakes learned to coexist; the birds, for example, built their nests at the far end of tree branches, inaccessible to the snakes.

But the islands where the brown tree snake has recently appeared, such as Guam, have no significant native snakes. Because of this, intruders such as the tree snake can cause the same environmental havoc they have wrought here.

Biologists estimate that the brown tree snake, which has no natural predators here, now outnumbers Guam's 150,000 people by about 10-1. In some places, "there are staggering densities" - as many as 12,000 snakes per square mile, Fritts said.

Most of those snake patches are in rural areas. But the biggest and meanest snakes seem to be heading downtown.

"All the large snakes are being found in urban areas," said Michael McCoid, a biologist with the Guam Division of Wildlife and Aquatic Resources. ''There is nothing for them to eat out there anymore except chickens, puppies and kittens - and they are all in urban areas."

It would be inaccurate, however, to paint Guam as a slithering tangle of snakes at every turn. The snakes are nocturnal and highly secretive. "Some people on the island have never seen a single snake," McCoid said.

But they are out there in the dark, stalking prey and ending up in the oddest places: toilet bowls, dresser drawers, the clothing rack of a fashionable boutique, the third floor of the Naval Hospital, poking out of an auto's air conditioning vents, and in the beds of small children.


There is, so far, no clear solution for stopping the snake.

McCoid and Fritts have been studying everything from the snake's eating habits to population structure to climbing techniques.

Meanwhile, researchers at the University of Colorado, the University of Arizona, Texas A&M and the National Institutes of Health have been probing the brown tree snake's sensory and chemical biology in hopes of finding a way to control or kill it.

"What we are doing is trying to find the weakest point in its biology to attack," explained Fritts.

Robert Mason, a researcher at NIH's Heart, Lung and Blood Disease Institute, is searching for any chemicals naturally produced by the snake that might serve as either an attractant or repellent.

"We are trying to identify something like a sex pheromone (a sex scent) that could be used in rounding the snakes up," explained Mason.

So far, no weapon has been found. One biologist tried to popularize snake cuisine, handing out to Guam's residents recipes for sweet and sour snake and snake adobo. But while island natives, known as the Chamorro, love to eat fruit bats, the snake dishes never really caught on.

On the southern coast of Guam, rippled with green mountains, Clay Carlson and Mary Jo Hoff set up a small ranch near the village of Inarajan to raise chicken, ducks, geese and rabbits.

Theirs is a tiny spread, rimmed by coconut and palm trees and the Pauliluc River, a part-time operation for the two retired University of Guam professors.

They never imagined the battle ahead of them. "We went two years without hatching anything," Hoff said. "Then we started taking precautions against the snake."

They tried to build snake-proof cages, but snakes penetrated them. Then they started collecting the eggs, using an incubator and protecting the youngest animals. "After they grow a bit, they are too big and the snake will leave them alone," Carlson explained.

Still, the snakes keep coming. Carlson and Hoff trapped 43 of them last year. "They seem attracted to something in the hatching and birth of things," Hoff said.

The story is the same for small domestic animals. "If there is a litter of puppies around, the snake will be around, too," said Richard Dorner, an island veterinarian. Puppies, he said, have been killed by snakes.

No studies have been done on the economic impact of the snakes, but Fritts and McCoid found that at least half the island's poultry operations reported problems.

No one wants to say for sure that snakes are are responsible for the ranches' closings.

But, Carlson said, "if you were a poor farmer working on the edge to get by, with this snake, you'd be screwed."

The Matsons rushed their son, Skyler, to a local clinic, where they were told not to worry because the snake venom is not considered poisonous to humans.

Skyler's forearm swelled "like Popeye," said Ernest Matson, who is a marine biologist at the University of Guam. By midmorning, the boy had become ''limp like spaghetti. . . . He couldn't stand up or talk or even keep his eyes open."

With Ernest Matson raging and Yvonne Matson, who was 7 months pregnant, ''on the verge of hysteria," Skyler was admitted to Guam Memorial Hospital, the island's major medical facility.

By the next morning, the venom's hold had weakened. "He was coming around. It was like he had a hangover," the father said.

Such cases have health officials puzzled. The effects of the bites have included swelling on the bitten limbs, lethargy, breathing problems and respiratory arrest. The most severe cases have involved newborns.

"When adults get bitten, it is usually because they've disturbed the snake," said Dr. Robert Haddock, the chief epidemiologist for the Guam Department of Public Health and Social Services.

"But the snake seems to go looking for children. . . . We have a case where the baby was sleeping between two adults and the snake found it and tried to chew on a finger." Skyler Matson is back home and now shares his bedroom with his baby sister. Yvonne Matson covers drains with pots and stuffs newspaper between pipes each night in an effort to keep snakes out.

For all the precautions, Ernest Matson does not feel much safer. "You can't snake-proof a house on Guam," he said. "They can get through anything."

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