Filed Under:

Hungry Snakes Trap Guam In Spidery Web

Play associated audio

The Pacific Island of Guam is experiencing a population explosion — of spiders.

There are more spiders there now than anyone can remember. To get a sense of how weird the situation is, I started out in Maryland. On my front porch, overlooking the Severn River.

At 6:30 in the morning on a cool fall day, I find two spider webs in a matter of five minutes. But if I were on the island of Guam, I might find 70 or 80 spider webs in five minutes.

Ecologist Haldre Rogers realized something strange was going on as she went roaming through the jungle on Guam and three nearby islands. "While I was doing that," she recalls, "it appeared that there were tons more spiders on Guam than there were on other islands."

Rogers is a researcher from the University of Washington, and she was actually in Guam looking for snakes. The brown tree snake invaded Guam over 60 years ago — they sneaked in aboard boats or in the wheel wells of airplanes. And now they're everywhere: about 2 million of them.

But the spider thing was just too bizarre to pass up. So Rogers started counting spider webs on the islands.

In the dry season, Guam had about 2 1/2 times more spider webs. "And 40 times more webs in the wet season than on the nearby islands," she says.

Forty?! "Forty times, yes," she assures me.

One that seemed to be everywhere was a great big yellow and black critter called Argiope appena, or the banana spider. "And actually," she says, "what we found was, their webs were much bigger on Guam than on the other islands, they were 50 percent larger on Guam."

More, bigger, better ... if you're a spider.

This all came about because the introduced tree snake multiplied only on Guam and ate almost all the birds. There are literally just a few hundred birds left there.

Since birds eat spiders, this is good news for spiders. In fact, great news, because birds also ate some of the bugs spiders eat, so there's now more food for spiders, too.

For ecologists, Guam is now a big experiment to see what happens when a top predator disappears from an ecosystem. They suspect plants could be affected too; many depend on birds to spread their seeds.

But Rogers wants to remind people that Guam is still a nice place. Says Rogers: "The average person doesn't come across that many spiders, because most people don't go traipsing around in the jungle that much."

If you do plan to do that, just watch where you're going.

Copyright 2012 National Public Radio. To see more, visit http://www.npr.org/.

NPR

In 'Rams,' Two Icelandic Brothers Tend Troubles Of Flock And Family

Gummi and Kiddi are two sheep-herding brothers who've spent a lifetime butting heads near the top of the world. When a disease threatens their flocks, they must overcome decades of estrangement.
NPR

Beer And Snack Pairings: A Super Bowl Game Everyone Can Win

Which beer goes with guacamole? How can a brew complement spicy wings? Two craft beer experts share their favorite pairings and help us take our Super Bowl snack game to the next level.
NPR

Tourists Flock To New Hampshire For Front Row Seat To Presidential Politics

NPR's Robert Siegel reports on people who are not involved in presidential campaigns traveling to New Hampshire to observe the action surrounding the primary. There are families trying to give their kids a civics lesson, couples trying to see presidential politics up close, and groups of students who serve as interns for campaigns as part of their studies.
NPR

OK, Google, Where Did I Put My Thinking Cap?

It can be too easy for students to Google an assignment before they stop to think about it. Some researchers say we're losing our critical thinking and memory skills by relying on the search bar.

Leave a Comment

Help keep the conversation civil. Please refer to our Terms of Use and Code of Conduct before posting your comments.