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Eradication of Invasive Species on Midway Atoll NWR

Photo Point on Midway Atoll NWR's Eastern Island after Tsunami spread Verbesina | Dan Clark USFWS
Photo Point on Midway Atoll NWR’s Eastern Island after Tsunami spread Verbesina | Dan Clark USFWS

Midway Atoll National Wildlife Refuge in the Pacific Ocean is home to more than 3 million seabirds. This includes 1.5 millions Laysan albatrosses, which is 65 percent of the global population, making it the world’s largest Laysan albatross colony. Why is this important? Nineteen of the 21 species of albatross are threatened with extinction, and one factor inhibiting recovery is an invasive plant known as Verbesina encelioides, also known as golden crownbeard. This plant, considered invasive at Midway Atoll National Wildlife Refuge, stands as high as a corn-stalk and has been blocking critically needed nesting space for the albatross and other seabirds.

Thanks to the hard work from the U.S. Fish and Wildlife Service, this plant is finally being eradicated on the 335-acre Eastern Island, which is part of Midway Atoll National Wildlife Refuge. This removal is possible because of a $1 million National Wildlife Refuge System grant given to the U.S. Fish and Wildlife Service and matching funds from the National Fish and Wildlife Foundation.

Early Signs of Success

An endangered Short-tailed albatross on Sand Island, Midway Atoll National Wildlife Refuge. A pair of short-tailed albatross on Eastern Island | Andy Collins NOAA Office of National Marine Sanctuaries
An endangered Short-tailed albatross on Midway Atoll National Wildlife Refuge.   | Andy Collins NOAA Office of National Marine Sanctuaries

Efforts may finally be paying off. Between 2012-2013, Laysan and black-footed albatrosses nested at near-record levels on Midway Atoll. Biologists will need three more years to know for sure if the rise is due to the golden crownbeard control, but it looks promising. In addition, one of the world’s most endangered seabirds, a short-tailed albatross chick, hatched. This was only the third hatching in recorded history outside of three small islands near Japan; the earlier hatchings also occurred on Midway after plant control efforts began.

“The early success of this project is exciting, because the techniques we’ve developed could help control invasive plants in other island environments and perhaps even on the U.S. mainland,” says John Klavitter, invasive species coordinator for the Refuge System and Midway Refuge’s former deputy manager. “Invasive species — non-natives that harm the environment, economy or people — are extremely challenging to manage, let alone remove,” added Klavitter.

So how did it get to Midway?

It is estimated that the golden crownbeard was introduced to Midway in the 1930s from the southwestern United States and Mexico. It likely arrived as seeds in the over 9000 tons of soil that were imported when the refuge was a military base. By the late 1990s, the plant covered most of Midway’s three islands which is when eradication efforts began. This infestation reduced seabird nesting density, reproductive success, albatross chick survival, and biodiversity. The birds don’t build nests on existing golden crownbeard stands which dramatically reduces available nesting habitat. When new stands grow on areas that have already been nested, the plant encloses and entraps chicks preventing the parents from finding them and results in death by starvation. Golden crownbeard is also home to aphids, scale insects, and ants. The ants prey on the eggs of the birds thus decreasing survival rates further.

 

Strong efforts despite logistical challenges

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Volunteers pulling the nonnative plant, Verbesina from Midway Atoll NWR | John Klavitter/U.S. Fish and Wildlife Service

Eradication efforts have not been easy. Although efforts began in the 1990s, the program intensified in 2003. The program has included control by hand-pulling, mowing, and herbicide application. For the past two years, crews have hand-sprayed the invasive plant almost daily with herbicides. With so many nests on the island year-round heavy machinery such as tractors is not an option.

Despite logistical challenges, the spraying has knocked out most of the mature golden crownbeard plants on Eastern Island. If all goes well, emergent seedlings will be gone by early 2017 on Eastern and Spit islands and by early 2018 on bigger Sand Island. Native grasses and other native plants are being replanted to restore seabird nesting habitat, secure coral sand and build coastal dunes to protect against waves.

 

Preventing re-Infestation

To guard against re-infestation or invasion of another atoll, the Refuge imposes strict quarantine procedures. All personnel traveling to Eastern Island must pass through shoe-cleaning stations at the boat pier. All equipment is cleaned before transport from Honolulu to Midway and before use on Eastern Island. Travelers from Honolulu to Midway must also clean their shoes and gear before flights and voyages. Only new clothing and thoroughly cleaned equipment are allowed at the other atolls and islands within the Papahānaumokuākea Marine National Monument.

Invasive species are a problem throughout the entire refuge system. There is hope that the success of these efforts can serve as an example for future projects to help eradicate even more invasive species.

Click here for the full story from U.S. Fish and Wildlife Service

Click here for more information about eradication efforts written by the Friends of Midway

Permanent link to this article: https://www.refugeassociation.org/2014/04/eradication-of-invasive-species-on-midway-atoll/

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