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This post comes to us from biologist Steve MacLean, director of The Nature Conservancy’s Bering Sea Program in Alaska.

Last summer, when biologists walked along the rocky cliffs on Rat Island, one of more than 2,000 islands in Alaska’s Aleutian chain, they encountered an eerie silence. This place should have been a cacophonous and lively melee of bird calls. 

The reason for the silence? Invasive rats. They colonized the island after a Japanese fishing vessel wrecked against its rocky shore in 1798. Their numbers multiplied, and for more than two centuries the voracious rats have preyed on bird eggs and young chicks. The birds gone, silence spread from shore to shore.

This summer, biologists discovered something new at Rat Island: encouraging signs of bird life. The reason? A seabird restoration project is at work.  

Over the course of a week-and-a-half in the fall of 2008, our project team, led by the U.S. Fish and Wildlife Service, Island Conservation and The Nature Conservancy, broadcast bait across the island. Our objective was this: removing the rats and reclaiming the island as productive seabird breeding habitat.

We’ve received initial evidence that the invasive rats from Alaska’s remote Rat Island are no more. Biologists report three peregrine falcon nests. Several nesting bird species — black oystercatchers, ptarmigan, Aleutian cackling geese and others — appear to be more abundant. This means that the lively din of puffins, auklets and other birds may soon return.

But with the good news of returning nests comes an unexpected report.

In June, project biologists reported the discovery of some dead birds: Most notably, 43 bald eagles and 213 glaucous-winged gulls.

It’s an absolutely shocking discovery. In Alaska, where the population of bald eagles numbers 50,000, we have an undeniable attachment with eagles — that eagles have died is deeply disappointing to us.

To learn more, we’ve expedited tissue samples to the National Wildlife Health Center in Madison, WI. We expect pathologists’ results from these tests in coming weeks.

In the meantime, it leaves us with a lot of time for serious soul-searching. Was our own restoration project responsible for this devastating loss? What’s the future of Rat Island?

For now, we know the project was responsible for at least some of the bird deaths. This deeply saddens us, and reinforces our commitment to ensuring that our projects provide the maximum benefit to Alaska’s biodiversity and minimize the risk associated with each project. While no restoration project like this one can be entirely risk free, we know we can learn from this project to ensure that all restoration projects around the world are conducted as safely and effectively as possible. 

As for the future of Rat Island, we’re optimistic. For more than 200 years, invasive rats have ruled this remote island, essentially killing off the puffins, auklets, sandpipers, ducks and songbirds that would normally nest in what is otherwise optimal habitat.

The arc of experience tells us our optimism is warranted. Worldwide, more than 300 similar rat eradication efforts have proved successful. Nonetheless, much work remains for restoration ecologists. Invasive rats have been introduced to about 90 percent of the world’s islands. These unwelcome predators account for 40 to 60 percent of all recorded island bird and reptile extinctions.

As we continue, we’re prepared to commission an independent review to fully evaluate the project. We have every reason to expect that the project will be completely successful and the birds of the Aleutians will once again fill Rat Island with a cacophonous celebration of avian diversity.

If, after two years of careful monitoring, Rat Island proves to be once again free of the rats that have decimated the bird populations, we hope to remove the outdated moniker, and restore the island’s original Aleut name: Howadax, pronounced “How-a-tha” meaning “entry” or “welcome.” 

Please join us in welcoming back the birds of Howadax.

-- Text by Dustin Solberg, Cool Green Science Blog