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By Dustin Solberg
Alaska's Aleutian Islands are home to 50 million seabirds, making this far-flung archipelago one of North America's 10 birding hotspots — and the best seabird habitat in North America.
But something's awry on the unfortunately but aptly named Rat Island, a 10-square-mile dot in the Aleutians. Invasive rats have pillaged seabird nests here since they first spilled from a 1780's shipwreck that — except for the stowaway rats — left no survivors.
So in September 2008, The Nature Conservancy and its partners set out across the Bering Sea to eradicate the rats once and for all — and embark on the most ambitious island habitat restoration project ever undertaken in the Northern Hemisphere, involving helicopters and a boat ride into the teeth of North Pacific's worst weather.
Missing: Puffins, Auklets and Murres
Though a cacophony of seabird cries fills the skies along many craggy coastlines in the Aleutian Islands, the cliffs of Rat Island are strangely quiet.
This unnatural absence of puffins and auklets in this otherwise healthy habitat in the Alaska Maritime National Wildlife Refuge is caused by the invasive Norway rat, a formidable predator for these birds.
The populations of the Norway rats run amok, feasting on eggs and young chicks during the birds' brief nesting season.
"In the Aleutians, colonies of seabirds such as puffins and auklets are like the biological engine that keep these rich systems humming," says Steve MacLean, director of the Conservancy's Bering Sea program. "An Aleutian Island without seabirds is missing something vital."
Rat Island wasn't always bird-free, though, according to archeologists and biologists.
In the remnants of an Aleut village — dating from 800-1400 and 1780-1800 — a forgotten midden where lush grass grows today contains the bones of birds no longer found on the island. Other archeological excavations reveal that the bird decline coincided with the arrival of the rats.
"At the point where rats were introduced, there seems to be a pretty clear and sudden drop in the number of bird families and species and individuals," says U.S. Fish and Wildlife Service archeologist Debbie Corbett.
Rough Weather, Helicopters and Bait
So bringing back the seabirds means ridding the island of its rats. And the September voyage to the island may have done just that.
Biologist Stacy Buckelew of Conservancy partner Island Conservation and a crew of 11 traveled in a seaworthy 158-foot fishing vessel that had time and again proven itself in the notorious storms of the North Pacific.
The weather on this trip was trademark Bering Sea: Stormy 12-foot seas sent waves of icy water splashing over the ship's stern. Gales reached 40 knots.
"On the first day, we didn't get off the ship because the swells were too big," says Buckelew.
The boat and its eager crew met the rest of the restoration team on the island. This included two helicopters equipped with highly accurate GPS-guided navigation systems. The pair hop-scotched down the Aleutian chain until they reached distant Rat Island. Then, over the next ten days, the pilots traveled along a digital grid over the entire island, distributing rat bait laced with small amounts of rodenticide.
For good measure, they did it twice: The survival of a single rat jeopardizes the seabirds' safe return.
The helicopter campaign was a scaled-up version tested on a small set of Aleutian islands in 2006. If the effort works, Rat Island will be the planet's second-largest island ever restored for native species using these aerial eradication techniques.
Follow-up monitoring the next two summers will confirm if Rat Island is rat-free for the rich diversity of birds that once thrived on the island.
A Global Model
Around the world, introduced non-native species such as rats are a leading cause of extinctions in island communities.
The Rat Island restoration is one example of new global efforts to eradicate invasive species in otherwise healthy island ecosystems. Invasive rats have been introduced to about 90 percent of the world’s islands and are responsible for 40 percent to 60 percent of all recorded island bird and reptile extinctions.
Success would also mean that the team may get a chance to rescue another and larger Alaskan island: Kiska Island, where rats threaten a still-healthy colony of 5 million least auklets — the largest of its kind in the state. Computer models show the colony's very survival is at risk.
With its partners, the Conservancy intends to restore 100,000 acres of lost habitat by eradicating rats on more islands.
"This is a turning point for seabirds in the Aleutians," says Randy Hagenstein, director of The Nature Conservancy in Alaska. "Introduced predators are the most critical threat to seabirds here and there is no better way to ensure their habitat remains healthy."
Dustin Solberg is a marketing specialist for The Nature Conservancy in Alaska.
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Photo credits (top to bottom, left to right): © Island Conservation (the cliffs of Rat Island); © Michael McBride (puffin)
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