07/29/2016

New Zealand Chooses to Save Prey Over Predator

4:18 minutes

 

A pair of rats, from Shutterstock
A pair of rats, from Shutterstock

New Zealand is well-known for harboring hundreds of beautiful native bird species, many of which have called the archipelago home for millennia. Mammalian species, on the other hand, are not native to the island nation — all except two surviving bat species arrived along with humans a mere 700 years ago. Since then, nearly a quarter of the country’s native birds have gone extinct.

Now the government of New Zealand has announced it is adopting a rather extreme conservation strategy to save its birds. It wants to wipe out an entire population of eight mammalian predators, including rats, possums and stoats. But can the country turn back the clock 700 years to before these non-native predators arrived?

Sarah Dawson, director of the Wohlsen Center for Sustainable Environment at Franklin and Marshall College, thinks it is a possibility. But the effort will not be without some risks.

“This is definitely the largest scale removal ever attempted,” Dawson says. “And when we’re talking about things like rats and mice in particular — you have species refuging on private lands and in homes, so there’s going to be a lot of public compliance and likely assistance necessary that’s going to be difficult — costs in billions of dollars. And also they’re talking about using poisons, which will be effective against the non-native mammals, but there could also be some non-target species like domestic dogs being affected.”

Though there are risks and costs associated with the effort, Dawson says conservation on New Zealand is particularly important.

“It’s not just New Zealand protecting bio diversity, it’s critical across the globe because we depend on it for food and housing and medicines both known and almost certainly unknown,” Dawson says. “We’re losing thousands of species each year because of impacts from humans. But islands in particular have a disproportionate amount of unique bio diversity because their species have been evolving in isolation for so long. So though islands comprise only about five percent of land area, they do contain about 20 percent of all the species on the globe and so conservation efforts can be more efficient here. But for New Zealand in particular, their unique fauna are also a major economic driver in the form of tourism dollars.”

There is, however, reason to hope that, although extreme, this eradication project will be successful.

“It does sound ghastly but I do think it’s a critical component of a comprehensive conservation plan,” Dawson says. “It’s actually been used in some form or another in more than a thousand other places — mostly islands — and sometimes successfully, sometimes not successfully…But it is important to note that New Zealand is not at all new to this sort of strategy. They’ve actually had success already in removing stoats, possums, rats and also other invasive species from over 100 of their smaller outlying islands, so they’re well practiced.”

—Elizabeth Shockman (originally published on PRI.org)

Segment Guests

Sarah Dawson

Sarah Dawson is the director of the Wohlsen Center for Sustainable Environment at Franklin and Marshall College in Lancaster, Pennsylvania.

Segment Transcript

JOHN DANKOSKY: And now it’s time to play Good Thing, Bad Thing. Because every story has a flip side, New Zealand is well known for its beautiful native bird species, many of which have called the archipelago home for millennia. Land mammals, on the other hand, are not native to the island nation. They arrived along with humans about 700 years ago. Since then, nearly a quarter of the country’s native birds have gone extinct.

Now, after 50 years of futile efforts to save its native avian species, the government of New Zealand is adopting a pretty extreme conservation strategy. The plan is to wipe out an entire population of non-native mammalian predators, including rats, possums, and stoats. Joining us to explain all this is Sarah Dawson, Director of the Wohlsen Center for Sustainable Environment at Franklin and Marshall College. Welcome to Science Friday.

SARAH DAWSON: Thanks. Thanks for having me.

JOHN DANKOSKY: So first of all, what makes these birds so special to the people of New Zealand, and why is it so important to protect them?

SARAH DAWSON: Well, I think, taking a step back, it’s not just New Zealand protecting. Biodiversity is critical across the globe, because we depend on it for food and housing and medicines, both known and almost certainly unknown, and we’re losing thousands of species each year because of impacts from humans.

But islands in particular have a disproportionate amount of unique biodiversity because their species have been evolving in isolation for so long. So, although islands comprise only about five percent of land area, they do contain about 20 percent of all the species on the globe. And so, conservation efforts can be more efficient here. But for New Zealand in particular, their unique fauna are also a major economic driver in the form of tourism dollars.

JOHN DANKOSKY: Oh, so people come to see the birds. So, this plan calls for eliminating all rats, possums, and stoats, which sounds, frankly, I don’t know, Sarah, kind of ghastly. Is this the best way to protect the native birds?

SARAH DAWSON: Yeah, you know, it does sound ghastly, but I do think it’s a critical component of a comprehensive conservation plan. In addition to invasive species, major causes of biodiversity loss include things like pollution and over-harvesting and habitat destruction, and certainly all of these things need to be addressed in conservation.

But for many islands, and an island nation like New Zealand in particular, they have a cohort of species that have not evolved with predators, which makes them especially susceptible to these predator invasions. And so, their ground nesting birds like kiwis have no defense against generalist predators like stoats and rats. And so, I do think that invasive species control really needs to be their top priority.

JOHN DANKOSKY: Yeah, and kiwis are threatened. This is the national bird.

SARAH DAWSON: It is, yeah. Cute little guys.

JOHN DANKOSKY: So where else has a strategy like this been used? Was it successful, trying to wipe out all the predators like this?

SARAH DAWSON: Yes, it’s actually been used in some form or another in more than 1,000 other places. Mostly islands, and sometimes successfully, sometimes not successfully. So recent success stories include getting rid of the goats on some of the Galapagos Islands and pigs from the Channel Islands. Guam, with the brown tree snake, is probably the most famous case of an unsuccessful invasive species removal.

But it is important to note that New Zealand is not at all new to this sort of strategy. They’ve actually had success already in removing stoats, possums, rats, and also other invasive species from over a hundred of their smaller, outlying islands, so they’re well-practiced.

JOHN DANKOSKY: We just have a few seconds left, but is there a worst case scenario? Could something really bad happen by trying this?

SARAH DAWSON: Well, I think they need to try. This is definitely the largest scale removal ever attempted. And when we’re talking about things like rats and mice in particular, you have species refugia on private lands and in homes. So there’s going to be a lot of public compliance and likely assistance necessary that’s going to be difficult, costs in billions of dollars. And also, they’re talking about using poisons, which will be effective against the non-native mammals but there could also be some non-target species like domestic dogs being affected.

JOHN DANKOSKY: We’ll be watching. Sarah Dawson, director of the Wohlsen Center for the Sustainable Environment at Franklin and Marshall College. Thanks so much.

SARAH DAWSON: Thanks for having me.

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