The Army Corps of Engineers often find themselves in the unenviable position of defending the status quo against relentless change. Twenty years ago the Corp dredged the Columbia River to accommodate ships of increasing draft. They piled the dredging spoils on Rice Island. Caspian terns, native to the Pacific Northwest, like nesting in soft sand and Rice Island had plenty of sand. It was also protected form predators. The terns were fruitful and multiplied. Eventually they numbered over 20,000—70% of the world’s population of Caspian terns.
They were also voracious, eating 16 million salmon and steelhead smolts each year—17% of the migrating juvenile population. The birds were suddenly a menace. Federal authorities determined a solution: move the terns.
It seems that Caspian terns are easily led. Using sound systems and decoys, the U.S. Fish and Wildlife Service lured the terns down the river to East Sand Island near the mouth of the Columbia, hoping they would find something other than young salmon to eat. The image of otherwise mature adults boating down the river broadcasting tern songs is precious. Far be it from me to further abuse their self esteem; I’m sure their colleagues made them pay dearly.
Resistance is futile
Reluctant terns were encouraged more forcibly. Their eggs were stolen, their rookeries were intersected by fences, and their nests were buried beneath a crop of winter wheat. Resistance was futile.
The government seemingly succeeded. Within a few years the number of salmon eaten by the terns of East Sand dropped somewhere between 3.5 and 7.7 million, an oddly ambiguous range. But environmentalists objected, several species of salmon were still almost extinct, and the alternate prey species favored by the terns (herring and anchovies) were fleeing global warming into colder water. Federal authorities determined a solution: move the terns.
They now plan to spend $2.4 million to move the terns to Sequim (on the Strait of Juan de Fuca), Oregon, and San Francisco. It’s questionable whether even the alluring folks of the Fish and Wildlife Service can capture a tern’s attention for that distance.
But that doesn’t settle the problem of the cormorants.
What about the cormorants?
Even Fish and Wildlife isn’t certain why the double-crested cormorants began settling on East Sand. Typically they prefer nesting on sea cliffs and ledges. No one knows much about the habits of cormorants; they’ve been paying attention to the terns.
Salmon makes up a smaller percentage of a cormorant’s diet but they’re a much bigger bird—four times the size of a tern—with an appropriate appetite. Last year they ate 6.4 million salmon, significantly more than the terns. It’s a problem. Federal authorities determined a solution: move the cormorants.
Only the cormorants are less tractable than the terns and not as easily swayed by a pretty voice or bedroom eyes. So the authorities in such matters enlisted several bald eagles to intimidate them. They installed posts on East Sand for the eagles to roost. The eagles behaved as expected, swooping down to take their prey. Nearby cormorants paid no attention.
Ah, the magnificent indifference of Nature.