The Rowi Kiwi
As the previous videos show, humans can disrupt ecosystems. Even when they're trying to solve a problem, their actions can cause great harm. Introducing living things to places they don’t naturally live provides another example of this.
Before humans arrived in New Zealand, dozens of flightless bird species lived and thrived there. With few natural predators, these species had adapted to living on the ground instead of in trees. European settlers brought in rabbits, but by the late 1800s, the rabbit population had grown out of control. To manage this, humans brought in an aggressive predator: a type of weasel called a stoat.
Some nonnative plants and animals do not harm the ecosystem they live in. Those that do, like stoats, are called invasive species.
As you watch this video, pay attention to how the introduction of the stoat to New Zealand devastated one type of flightless bird: the kiwi. Rowi kiwi, like the one Joel photographs in the video, are the rarest kiwi species still alive today.
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Statistics
- Size: 16 in. long, 4–6 lbs.
- Diet: worms, spiders, snails, and other invertebrates; also, fallen berries and seeds
- Natural predators: the laughing owl—now extinct—which often chased kiwi and other prey on foot
- Range: 3.9 sq. mi. in the Okarito forest (western South Island, NZ), and a few predator-free islands
- Population: fewer than 400 animals
- Why endangered: invasive species (especially stoats) preying on rowi chicks and eggs
Did You Know?
- Rowi kiwi dig holes in the ground, called burrows, which they use for shelter and as nests.
- Their loose, fluffy plumage is adapted to ground-dwelling life and looks more like fur than feathers.
- To help protect and grow the rowi population, one program (Operation Nest Egg) removes eggs from nests and raises chicks on islands with no predators. Kiwi released back into the wild are 15 times more likely to survive than those raised with predators around.
JOEL (voiceover): More than 80 million years ago, the islands of New Zealand had almost no mammalian land predators. No bear or dear or foxes, nothing with four legs and warm blood was stirring . . . literally, not even a mouse. But there were plenty of birds. And their main predators were other birds—flying ones. With few ground-dwelling predators and plenty of food, some birds lost their ability to fly altogether. Eighty million years of evolution created an ecosystem with 32 flightless bird species, more than any other place in the world. There were 10-foot tall birds called moas, the world’s heaviest parrot, takahe, weka, millions of kiwi birds. Together, they owned the forest floor. Kiwi are flightless, and they’re the only bird in the world to have adapted nostrils at the end of their bill. It helps them smell and feel for food underground. Their long beaks tap the ground, probing for and retrieving insects. But focusing on the forest floor, and not being able to fly has cost them in the long run.
KIM: So this is our stuffed stoat.
JOEL: So this little guy, that’s causing a lot of the trouble, this thing?
KIM: Yeah.
JOEL: Where are they from originally?
CATHERINE: Europe.
JOEL: Wow. It’s a mustelid, it’s in the weasel family.
KIM: It is, yep.
JOEL: And that little bitty thing has led to the ruination . . . the extinction of birds here?
KIM: Definitely.
JOEL: So people brought in rabbits and then the rabbits got overpopulated so they brought in stoats.
KIM: Yeah.
JOEL: And then the stoats just cleaned the clock of everything here.
CATHERINE: Exactly.
KIM: Biggest threat to New Zealand native wildlife.
JOEL: That’s it, wow. It’s not much, is it? But it’s everything.
JOEL (voiceover): Stoat, weasel, whatever you want to call it, it’s one of the world’s most destructive invasive species. These guys are in a land they don’t belong in, and they’re great at killing flightless birds.
Take Notes
In the space below, write short responses to the following:
- What evidence in the video supports the idea that an introduced predator caused a change in the populations of kiwi and other flightless birds?
- What additional evidence would you need to support the claim that this disruption caused the flightless bird population to drop?
