The U.S. Army Corps of Engineers doesn’t plan to shoot any double-crested cormorants at a breeding colony at the mouth of the Columbia River this year, but wants to take up to 500 eggs.
The Audubon Society of Portland has asked that nothing happen until both the Army Corps and the U.S. Fish and Wildlife Service, which issues the depredation permit, investigate why the birds abandoned Oregon’s East Sand Island in 2016 and 2017.
The Corps has shot more than 5,000 adult double-crested cormorants and destroyed more than 6,000 nests at East Sand Island since passing a management plan three years ago in an attempt to control the massive colony. The birds prey on juvenile salmon and steelhead, some of which are listed under the federal Endangered Species Act.
The agency will not shoot double-crested cormorants this year because of nesting activity in 2017 when thousands of birds abandoned the island and nests full of eggs for much of the season. Summaries on the Corps’ website and statements to the media indicated the presence of bald eagles could be to blame for the birds’ dispersal. A similar situation occurred in 2016 as well.
“It is simply not credible for the agencies to ignore the fact that the 2016 colony collapse, in which more than 16,000 cormorants abandoned their nests in a single day, followed weeks of relentless shooting of adult birds and came days after federal agents initiated egg oiling and nest destruction activities in the colony,” wrote Bob Sallinger, conservation director for the Audubon Society, in a letter sent to the agencies in March.
This year, the Corps will move into the second phase of its plan, which still includes the take of up to 500 double-crested cormorant eggs but focuses more on nonlethal hazing and restricting available nesting habitat.
The Corps’ depredation permit application is under review and has not been approved yet.
East Sand Island’s double-crested cormorant colony was set to be reduced from over 14,000 breeding pairs recorded in the 2015 management plan to no more than 5,380 to 5,939. There were approximately 5,000 to 6,000 individual double-crested cormorants on the island at the end of the nesting season last year, according to Army Corps spokesman Rick Hargrave.
The birds, one of three cormorant species typically seen on the North Coast, arrive at the island in late March and early April and leave in the fall. The colony on East Sand Island at one point was believed to account for more than 40 percent of the entire Western population of double-crested cormorants. The island is also home to a large Caspian tern colony that has been under a management plan to restrict nesting habitat since 2008.
Colony failure among the double-crested cormorants was one of the Audubon Society of Portland’s chief concerns from the very beginning. In his letter, Sallinger also referenced concerns held by researchers who had spent years on the island studying the birds for the Corps.
Daniel Roby, a professor at Oregon State University who led research teams on East Sand Island, said in a letter submitted during a public comment period when the management plan was still being drafted that the Corps ignored the studies it funded on the island to come to very different conclusions than researchers. He said the Corps exaggerated the risks of using types of nonlethal management techniques and downplayed the risk and uncertainty of killing the birds.
At the time the Corps was drafting the cormorant management plan, the agency emphasized the lethal option over others, saying methods such as limiting the nesting area, hazing birds off the island or luring them to other locations were risky. Such actions could disperse the birds throughout the estuary, driving them farther upriver where, with fewer prey options, they might pose more of a threat to young migrating salmon, Corps spokespeople said.
The Audubon Society of Portland argues this is what is happening now. When the birds abandoned East Sand Island in 2016 and 2017, the number of cormorants using the Astoria Bridge and other bridges as alternative nesting sites swelled.
“This situation at East Sand Island demands a full and public review,” Sallinger wrote. “Federal agencies have spent millions of public dollars pursuing a strategy that has precipitated the collapse of the largest double-crested cormorant colony in the world, potentially increased rather than decreased predation on listed salmonids and put the Western population of double-crested cormorants (at) risk.”
There are an estimated 45,047 breeding pairs in the Western double-crested cormorant population today, down from an estimated 76,306 in 2016.