Travel writers don’t sing the praises of Alaska’s “Rat Island.” But something utterly remarkable in the annals of biology and ecotourism is happening there.
By Rex Graham
The most common mammal on this rugged 10-square-mile island with the cringeworthy name is gone. Yes, the rats are kaput thanks to science and carpet bombing with rat poison.
Now, something utterly amazing is occurring.
Rat Island’s earlier name was Hawadax Island. It is part of the Aleutian Archipelago half way between Alaska and Russia. Its rodent-infested phase began in the 1700s. Ground-nesting birds were easy pickings. Arctic foxes were introduced, but they ate as many birds as rats.
One of the many birds that birdwatchers love, the American Black Oystercatcher, was down to one nesting pair on the island in 2008. Oystercatchers actually eat many more mollusks than oysters, but the “catcher” part is appropriate because prey species are often very good at hiding, and the two halves of the shell can be hard to separate. That’s where the oystercatcher’s long, bright-orange bill comes in
Craggy, wave-pounded shores and intertidal areas of the Pacific Coast of Alaska, Canada, the U.S. and Mexico Pacific Coast are the oystercatchers’ summer breeding grounds. The birds live year-round in as far south as the ice-free coast of British Columbia, Canada. They congregate in overwintering flocks.
American Black Oystercatcher a birding favorite
Birding tours to almost any of the thousands of Alaskan and Canadian Pacific islands offer a chance to see these comical-looking black birds with long orange bills, bright yellow eyes and oversized pink feet. They’re not joking, which is evident to other shorebirds that mistakenly try to share an oystercatcher’s territory.
Nine dead, oil-soaked oystercatchers were found dead on polluted shores after the Exxon Valdez spill in Alaska’s Prince William Sound in 1989. Petroleum chemicals persisted in the mussels a decade after the spill, but oystercatchers have bounced back there.
Rodents are as deadly to nesting oystercatchers and other seabirds as foxes or misguided oil tankers. Hawadax Island is a classic example. It had very few nesting birds — the rodents ate all the bird eggs and chicks they could find. There were no Snow Buntings or Song Sparrows on the island in 2008. Arctic foxes were part of the problem, and they were eliminated in 1984.
In 2008, it was the rats’ turn. In that spring breeding season, researchers saw only 1 Black Oystercatcher nest and 1 Rock Sandpiper nest on Hawadax. In the fall, when the rats had little else to eat, the U.S. Fish and Wildlife Service dropped grain laced with rat poison. It worked better (and worse) than expected. All the rats died, but so too, did 320 Glaucous-winged Gulls and 46 Bald Eagles. Those predatory birds presumably fed on rats that had ingested the poison.
The long-term effects have been much better. Even the gulls and eagles have rebounded. And in 2013, researchers counted 6 oystercatcher and 5 sandpiper nests on the 10-square-mile Hawadax. Even burrow-nesting Tufted Puffins had returned after their absence. “A range of terrestrial and marine birds have newly colonized, re-colonized, or increased in abundance following the eradication of invasive rats,” California and Alaska scientists said in the journal Biological Invasions.
The American Black Oystercatcher is widely distributed along the Pacific Coast of North America, but their habits are not yet well understood, and they are often under threat. In 2001 a group called the American Oystercatcher Working Group formed to share research data, bird-banding and wildlife management efforts, and ideas. The group’s many fundamental accomplishments are outlined on its website amoywg.org.