A Moveable Feast

Dan Roby fools Caspian terns into nesting on artificial islands (Photo: Dan Roby)
Dan Roby fools Caspian terns into nesting on artificial islands (Photo: Dan Roby)

By Lee Sherman Gellatly

When Dan Roby floated the idea of relocating 18,000 seabirds in 1999, there was a lot of eye-rolling among wildlife experts in Oregon. “No one believed it would work,” says Roby, an ornithologist at Oregon State University specializing in marine species. But everyone agreed that something had to be done. With suitable seabird habitat shrinking all over the West Coast, Caspian terns (Hydroprogne caspia) had begun nesting on a man-made island of sand dredged from the Columbia River and deposited in the estuary in the 1960s. By the turn of the millennium, the mound — dubbed Rice Island — was home to the world’s largest breeding colony of Caspian terns.

For fisheries managers, the colony posed a problem. The birds were gobbling up millions of young salmon and steelhead as they made their way to the ocean. “This must stop,” was the stern message from the National Oceanic and Atmospheric Administration (NOAA), the agency charged with protecting endangered migrating salmon stocks throughout the Pacific Northwest.

Dan Roby

So Roby turned to his former professor at Antioch College, Steve Kress, for guidance. Kress, who by then was directing seabird restoration for the National Audubon Society, had successfully restored colonies of Arctic, roseate and common terns in the Gulf of Maine. He agreed to help and flew to Oregon. The massive bird transfer began.

The biologists assembled an eclectic team from both U.S. coasts — an offbeat collective of artisans, entrepreneurs, scientists and engineers. There were craftsmen from Vermont (Mad River Decoy) and Oregon’s own Willamette Valley (Dave Smith Decoys) who created hundreds of tern look-alikes from plastic. There were digital-sound specialists from Fairbanks, Alaska (Alaska’s Spirit Speaks), and Bristol, Maine (Murremaid Music Boxes), who built audio systems to record and play back the sounds of nesting terns (“Caspian terns’ greatest hits,” Roby jokes). There were engineers from the Army Corps, who bulldozed tons of dredge soil to prepare the terns’ new colony site, East Sand Island, about 15 miles closer to the ocean than Rice Island. There were consulting scientists from the state and federal fish and wildlife agencies. And there were grad students to do fieldwork, which included creating barriers on Rice Island to deter nesting terns.

The basic idea: fool the terns with “social attraction” — audio and visual bird impersonations to draw them to the new site. Much to the surprise of the skeptics, it worked. Within two years, the colony had re-established on the new island. As hoped, the birds were eating far fewer salmon, choosing anchovies, sardines and other marine forage fish instead. Caspian terns, it seems, are food “generalists” — pragmatic eaters who’ll grab the easiest meal at the closest fast-food joint.

But NOAA wasn’t entirely content. The terns were still eating lots of salmon. If Roby could move terns 15 miles, maybe he could move them 400 miles — for instance, to Malheur National Wildlife Refuge on Oregon’s eastern flank. Malheur, once the “jewel in the crown” of the refuge system, is now awash in invasive carp. What if Caspian terns could be enticed to nest at the lake and, along with the thousands of resident white pelicans, eat up the invaders?

Sure enough, the artificial island built in Malheur Lake three years ago has drawn many Caspian tern nesting pairs with its “social attraction” strategy of decoys and birdcalls. It’s too soon to tell, Roby says, whether the island will become a regular haunt for the terns, but so far, the results are encouraging.


Oregon State ornithologists are carrying out studies from the Oregon coast to the Willamette Valley, Cascade Range, Columbia Plateau and the Zumwalt Prairie. See Avian Nations in the fall 2014 issue of Terra.

1 Comment

Nice tern tale, but there are many missing facts in this story. Notably, ternss were forced off Rice Island by a combination of rocket netting and harassment, the latter has continued to the present. They would have settled at East Sand Island without any inducement since they were prevented from nesting at nearby sites by human harassment. They nested at East Sand prior to nesting at Rice.

Second, no one that knew anything about terns was skeptical that they would move from Rice to East Sand, in fact that was the point of rocket netting. This is what terns do naturally when faced with disturbance or site destruction.

Third, given suitable habitat (insularity, food availablity) they would have settled at the site in Malheur Lake anyway where they have historically nested although the calls/decoys might have accelerated the occupation. However the success was dimished by the take over of the island by white pelican in 2013. I was looking for the success relative to white pelicans in 2014 and ran across this fluff piece.

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