Monday, January 5, 2015

Reversing alien species introduction: the island way

Humans are great at remaking environments by bringing new species in, but recently they’ve had a little success at reversing the process.

Bird-eating alien rats have now been removed from islands in many cases, plant-destroying rabbits as well, and recently, invasive birds have been targeted.

(Image: Atiu in the Cook Islands is nearly free of aggressive, invasive mynah birds. Credit: Google Maps.)

Off Hawai`i, rabbits have been removed and rat removal has been underway from Lehua Islet off Niihau.

Kure Atoll and Mōkapu Island off Molokai are rat-free now. 

The Nature Conservancy removed black rats from its preserve at Palmyra to Hawai`i’s south. 

New Zealand has had significant rat removal success on some of its smaller islands. 

In Alaska, an island once so infested that its formal name became Rat Island, is going back to its native name after the removal of the rats.  .

But what about invasive birds?

On the small island of Atiu in the Cook Islands, about 3,000 miles directly south from Hawai`i, they’ve taken to eradicating mynah birds.

The Indian mynah was brought into the islands of the Pacific for insect control—and they’re good at it. They’ve controlled army worms on Hawaiian lawns, and coconut stick insects on Pacific islands where the coconut pests have been prevalent.

Recently, after Atiu residents viewed images of mynahs pulling endangered Rimatara lorikeet chicks out of their nests and saw mynahs attacking lorikeets in flight, they launched a mynah eradication.

The birds locally are known as Kura. This lorikeet is a rare, gorgeous bird whose bright red feathers were important culturally. It was reintroduced to Atiu after being gone from the island for two centuries, but was doing poorly in part because of the mynah.

Atiu residents, with the help of experts, have removed more than 30,000 and they feel the end is near. On the other hand, the survivors are the birds most evasive and wary of traps. At last report from Cook Islands capitol Rarotonga, the mynah population was down to about 50 "real smart mynahs."

But of course, the coconut stick insect—also an introduction—is back in force.Apparently, there is some hope for control of the insect, as another native bird, a kingfisher, has added coconut stick insects to its diet.

Australia is also aiming to control mynah populations. The aggressive introduced birds have outcompeted many native birds for food, nesting sites.

One of the Australian catch phrases: You can have native birds or Indian mynahs, but not both.

© Jan TenBruggencate 2015

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