Isolation Proves Dangerous On 'Rat Island'

Originally published on August 1, 2011 9:00 am

Island. The very word connotes isolation — an isolation that has allowed pockets of animal species to evolve in safety over the course of thousands of years. But, as author William Stolzenburg writes in a new book, isolation can also be a weakness.

In Rat Island: Predators in Paradise and the World's Greatest Wildlife Rescue, Stolzenburg gives an account of the damage done to island ecosystems by invasive species like cats, weasels and rats — all animals that have at one point overrun new island environments and nearly destroyed native species.

One species Stolzenburg focuses on is the kakapo, a large, green, nocturnal parrot that is found only in New Zealand.

Stolzenburg tells NPR's Renee Montagne that because its only predators were in the sky, the kakapo had no need to fly and, therefore, couldn't.

"It exuded this particular scent also that was supposed to attract other kakapos," he says. "Of course, when the invaders got to New Zealand — when the rats and the cats and the weasels came to New Zealand — this was a bird that was just set up for massacre, and that's exactly what happened."

Saving New Zealand's Kakapos

Stolzenburg explains that in the 1800s, settlers arriving in New Zealand brought sheep and rabbits with them for game. Sheep ate much of the vegetation, and the rabbits, being rabbits, exploded in population. With their huge numbers and voracious appetites, they began eating the sheep's rangeland. So to deal with the rabbit problem, settlers introduced stoats — a member of the weasel clan and a terrific predator. But the stoats quickly found much easier prey than rabbits — kakapos.

Kakapo numbers quickly shrank so that, once New Zealand's third most populous bird, they soon only lived in small enclaves scattered around the country.

The New Zealand government made its first efforts at saving the bird in the 1890s, when it appointed a hunter and self-taught naturalist by the name of Richard Henry to be the birds' caretaker. He was tasked with establishing a refuge for the birds on an island off the southwest corner of New Zealand, known as Resolution Island. Henry spent the next 10 years gathering up as many kakapos as he could find — over 500 — and releasing them on the island.

Unfortunately for both Henry and the kakapo, Stolzenburg says, Resolution Island was within swimming distance of the mainland — and stoats can swim. Ten years after he began his project, Henry discovered a stoat on the island and realized his life's work had been in vain.

Conservation efforts slowed after Resolution Island, with kakapo sightings few and far between. But in the mid-20th century, the New Zealand government renewed its efforts to save the bird.

Conservationists were disheartened by their first efforts to find the parrots — old kakapo haunts were empty, and only a handful of birds were located. But an expedition in the 1970s was lucky enough to come across a population of close to 200 birds. It was the mother lode of the remaining kakapo population, and it provided conservationists with another opportunity to rehabilitate the species.

They began incubating the kakapos, protecting and guarding their eggs, and setting traps to ensure that no predators could get to the birds. But eventually, Stolzenburg says, even that sanctuary was invaded by feral cats. So scientists staged an emergency rescue and moved most of the remaining kakapo to Codfish Island, which had been cleared of all predators.

"It is basically about as pristine as you can find in New Zealand," Stolzenburg says. "They are now basically refugees; they're exiles from the mainland, and they are living their lives out on this island where they are being watched 24/7 by kakapo rangers who make sure that every egg, every mating now is a grand event, and they are watched very closely."

In Alaska, A 'Perfect Score' For Rats

Stolzenburg says there have been other, similar catastrophes across the globe. In the United States, Kiska — part of the Aleutian Islands off the coast of Alaska — was a pristine island environment until World War II, when the Japanese invaded and the U.S. became intent on taking it back.

Troops were sent ashore on Kiska, and at some point during their deployment, several rats also made their way onshore. Over the intervening years, the rats crossed 12 miles of rocky terrain — including a more than 4,000-foot volcano — and made their way to one of the world's most spectacular colonies of seabirds.

Known as auklets, Stolzenburg explains that the seabirds are tiny — about the size of a robin — and travel Kiska once a year to reproduce and nest in the crevices of the hardened volcanic rock.

"This was a perfect, perfect score for the rats," he says.

Here was this tremendous food supply that arrived every year, like clockwork. The rats would tear into the colony and massacre the auklets, hoarding them to survive the harsh Kiska winters.

Naturally, Stolzenburg says, scientists are concerned about the long-term impact the rats might have on the auklet population. Attempts to eradicate the rodents — largely with poison — have been difficult due in part to the island's remoteness as well as its rugged nature. The volcanic rock formations have essentially created a safe haven for the rats, and the logistics involved in dropping rodenticide over 100 square miles of terrain would require a gargantuan expedition — and one that is not guaranteed to succeed.

Between the auklets of Kiska and the kakapos of New Zealand, scientists have reason to both hope and be cautious. Stolzenburg says the islands essentially serve as metaphors for how the world's invasive species can irreparably alter fragile ecosystems.

"We have a very clear view of what's going on, and these islands provide that," he says. "It puts it on us. We put them in this position. Now we have a decision to make. We can either stand back and say, 'Let nature take its course,' or we can decide that this is our responsibility and do something about it."

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RENEE MONTAGNE, host:

Around the world, some of the most amazing creatures have evolved on the islands. Many of them are feathered and evolved in an isolated world where there were a few natural enemies. Ancient Hawaii was once alive with dozens more bird species than it has now. Once upon a time in New Zealand, you might've been awakened by the low booming call of a parrot called the kakapo. Then predators arrived.

That's the story found in a new book "Rat Island: Predators in Paradise." And wildlife journalist William Stolzenberg is especially taken with the fate of the kakapo.

Mr. WILLIAM STOLZENBERG (Author, "Rat Island: Predators in Paradise and the World's Greatest Wildlife Rescue"): The kakapo is a big, green, cuddly parrot that lives only in New Zealand. And it is flightless because, like a lot of the birds that gained access to these remote oceanic islands, had no predators except from the sky so it really did need to fly around, you know? And it became a flightless, walking bird.

It exuded this particular scent also that was supposed to attract, you know, other kakapos. But, of course, when the invaders got to New Zealand - when the rats and the cats and the weasels came to New Zealand - I mean this was a bird that was just set up for massacre and that's exactly what happened.

MONTAGNE: Which brings us to a fellow that you write about, Richard Henry, who was a self-taught naturalist, he ended up being at the center of a very early effort at conservation.

Mr. STOLZENBERG: Richard Henry, yeah, the ultimate handyman. He had started hunting to help feed the family, which was very poor. But he also, he took an interest in these birds. You know, he not only killed them for their skins; he would sell them to museums for specimens. But he would also, before killing them - and this is, you know, the contradiction of Richard Henry - he would sit and listen to them. You know, he grew to knew this bird like no other scientist ever would.

MONTAGNE: So the government of New Zealand, and this is back in the late 1800s, decides that it's going to set aside an island to save the kakapo when they realize that it's actually going extinct. They hire Richard Henry to go out there and be practically the only one on the island, and what happens?

Mr. STOLZENBERG: So he spends the next 10 years or so, braving, you know, great whitecaps and storms. And in traveling the sounds across the weather-beaten coast of New Zealand and bringing back these animals, and learning how to feed them, you know; he had to keep them in aviaries for certain times to make sure they're well fed before releasing them. And it was considered to be - this is going to be the fortress. This will be the sanctuary where we save these New Zealand natives.

MONTAGNE: Until the day when a weasel is spotted.

Mr. STOLZENBERG: Yeah, and somehow it has swum that mile from mainland to the island. And that for Richard Henry was a crusher, when for all purposes, this was his life's work - he was going to save the kakapo. He felt like his life's work had been in vain.

MONTAGNE: Decades after Richard Henry was crushed by the thought that all was lost, the kakapos were spotted again. How did that happen and what does that say about the potential for saving these creatures?

Mr. STOLZENBERG: When they came upon, in 1977, a population of about 200 of them then, and they had found the mother load of kakapos; not only that, they found the first females. And this is when they began to get serious about taking the kakapo's life into their own hands. They started incubating the kakapos under guarded watch. They started protecting and guarding their eggs. They would have people in tents watching the kakapos through remote TV cameras. And they would set traps all around the nest to make sure that no cats or rats could get to them.

Eventually, even that sanctuary was invaded. The cats got to them and they had an emergency rescue, whereby they took the last few handfuls of kakapos, moved them to an island called Codfish Island where most of them are now sequestered. And Codfish Island has been cleared of all predators, and so it is basically as about as pristine as you can find in New Zealand.

But it's still an island. I mean they are now basically refugees. They are exiles from the mainland and their living their lives out on this island where they are being watched 24/7 by Kakapo rangers who make sure that every egg, every mating now is a grand event. And they are watched very closely.

MONTAGNE: You write about another island, Kiska Island, which is also overrun by an invading species. Tell us just briefly about that.

Mr. STOLZENBERG: Kiska Island was a very important and pivotal site in the North Pacific theater of World War II. The Japanese had invaded Kiska early on in the war, and the United States was intent on taking it back. But also during this time, from some of these troops and some of their ships, a couple of rats made their way ashore, and over the intervening years, made their way over about 12 miles of this very rugged tundra, past a 4,000 foot iced-over volcano. And they came, eventually, to one of the most spectacular colonies of birds on the planet, where there's perhaps anywhere from one to six - some people even estimated 10 million of auklets nesting on this one tiny, little point of rock on the north side of Kiska Island.

MONTAGNE: And the rats, of course, could annihilate them eventually.

Mr. STOLZENBERG: This was a perfect, perfect score for the rats. I mean what we have here was, they have this tremendous colony of seabirds. They're tiny things. They're about three ounces. They're the size of a, say, of a robin or a sterling that we might be more familiar with. So you can imagine what that is for a rat to be coming upon these three ounce seabirds that have never seen anything like this in their evolutionary beginnings. They've never seen anything like a rat. They don't really know how to deal with a rat.

MONTAGNE: You know, you sort of wonder, you know, in this day and age why can't they just killed these invading species; poison them, or shoot them or get rid of them?

Mr. STOLZENBERG: Yeah. Well, first off, the size of this place, the enormity and the ruggedness of this place, and trying to get rats off of a place like this with surface means, like dropping poison on top of them, is a very daunting idea. This is a gargantuan expedition that is facing those who would save the auklets of Kiska.

MONTAGNE: So you have the kakapo and you have these little birds in the islands in the Aleutians who can't seem to be protected. What did you come away with thinking? I mean did you come away with hopeful? Or is this all very bittersweet, that we know these creatures are out there, but nature can be just one Rat Island after another?

Mr. STOLZENBERG: Yeah, there is great hope in the story and there is great fear for me in this story, in that these islands are metaphors for what's happening to the world. We have a very clear view of what's going on, and these islands provide that. So it puts it on us. We put them in this position. Now we have a decision to make: We can either stand back and say, let nature take its course; or we can decide that this is our responsibility and do something about it.

(Soundbite of song, "Similau")

MONTAGNE: William Stolzenberg is the author of "Rat Island: Predators in Paradise." You can glimpse a big green kakapo at NPR.org.

This is MORNING EDITION from NPR News. Im Renee Montagne.

STEVE INSKEEP, host:

And Im Steve Inskeep.

(Soundbite of song, "Similau") Transcript provided by NPR, Copyright NPR.