For the second year in a row, thousands of cormorants have vacated their nesting grounds at the mouth of the Columbia River, derailing a plan to shoot and kill the seabirds to protect fish.
East Sand Island is usually packed with around 15,000 nesting cormorants this time of year; but right now there are none – just a handful of abandoned nests and broken eggs.
As managers watch for the missing birds, advocates with the Portland Audubon Society are calling for the U.S. Fish and Wildlife Service to revoke the permits that allowed officials to shoot the birds in the first place.
The U.S. Army Corps of Engineers shot and killed 248 double-crested cormorants in April as part of a plan to cut the size of the seabird colony by more than half and reduce its impact on imperiled salmon and steelhead.
But Karim Delgado, public affairs officer for the Corps, said the agency’s culling activities are not the reason the birds have abandoned their usual nesting place.
The Corps stopped shooting the birds around April 27 when managers started noticing the birds were constantly being interrupted from nesting by bald eagles. Officials have counted as many as 40 bald eagles on the island harassing the cormorants and scaring them away from the island. As a result, there weren’t nearly as many nests on the island as usual, according to Delgado.
“I think the evidence bears out that our very limited culling of 248 double-crested cormorants did not affect the colony formation,” he said. “The lack of colony formation has been shown time and time again to be affected by bald eagle harassment in and around East Sand Island.”
Bob Sallinger, conservation director for the Portland Audubon Society, doesn’t buy that argument.
“The Corps wants you to believe these birds are desperately afraid of eagles but they’re not concerned with guys chasing them around in boats shooting them out of the air,” he said. “That’s absolutely ridiculous.”
Sallinger said the eagles may very well be having an impact on the cormorants.
“But we need to remember that eagles have been hanging out around that colony for years and years, and we’ve never seen anything like this,” he said. “When we really started to see abandonment was when the Corps really ramped up its activities.”
Sallinger sent a letter to the U.S. Fish and Wildlife Service Thursday asking regional supervisor Robyn Thorson to revoke the permits her agency issued to the Corps that allow for shooting cormorants.
“It is very possible that the combination of eagle predation activity and lethal control activity being conducted by the federal agencies are acting in a cumulative manner to put pressure on this colony,” he wrote.
The colony of double-crested cormorants on East Sand Island represents 40 percent of the entire population west of the Rocky Mountains. Sallinger said he’s worried it could now be at risk of collapsing.
Around 16,000 birds abandoned their nests on the island last year, too, leaving their eggs behind to be eaten by predators.
Officials recently removed three dead trees on the island that eagles were using as perches, Delgado said. They also agreed to allow a dead whale carcass to be placed near the site in the hopes of distracting the eagles and offering them an alternative food source (a move that critics argue may have drawn more eagles to the area).
In its Cormorant Management Plan, developed in 2014, the Corps made the case for shooting the birds on East Sand Island by arguing that other options would run a higher risk of dispersing the birds upriver where they were more likely to eat threatened and endangered species of salmon and steelhead. On East Sand Island, the birds are more likely to eat a larger portion of other fish coming in from the ocean.
Delgado said the Corps has recently seen as many as 10,000 cormorants roosting upriver on the Astoria Megler Bridge and counted around 600 active nests there. Meanwhile, they haven’t seen any cormorants on East Sand Island for “any significant period of time” since May 30.
“So, if the birds abandon this colony, according to the Corps, they’re more likely to go further up the estuary and cause more harm to salmon than they were causing on East Sand Island,” Sallinger said.
Delgado said revoking the Corps’ permits to kill the birds isn’t necessary because the agency has already stopped culling and won’t resume until the number of birds nesting on the island reaches a certain threshold. The agency will take eagle depredation into account as it decides how many cormorants should be killed, he said.
“We’re not going to haphazardly resume culling activities not knowing how the situation will unfold,” he said. “Ultimately, we’re just trying to reach a point where the ecosystem is as balanced as possible. So, it’s as much a concern for us that we would be culling too much as it would be that we weren’t culling enough.”