It is near the peak of double-crested cormorant nesting season, but federal biologists have yet to see a single egg on a Columbia River island that once hosted the largest breeding colony in North America.
The opposite is happening just upriver of East Sand Island on the Astoria Bridge.
A network of cormorant nests covers portions of the bridge. Photos show nests with clutches of eggs in a line on bridge struts and tucked into corners of the span’s vast understructure.
In mid-May, James Lawonn, aviation predation biologist with the Oregon Department of Fish and Wildlife, recorded as many as 10,000 cormorants on the bridge.
“That doesn’t tell us the full story,” Lawonn said.
Not all the birds he counted are associated with nests. From his post to the west of the bridge, Lawonn can only count the birds he sees on one side.
But a more complete count will soon be undertaken by U.S. Fish and Wildlife Service contractors, who will work by boat to count active nests on both sides of the bridge and on the understructure. Around 1,700 nesting pairs of cormorants were recorded on the bridge last year.
However, without any confirmed breeding by double-crested cormorants on East Sand Island so far this year, Lawonn’s counts are still a significant data point in trying to understand where the birds are nesting in the estuary.
“We’re coming up on the time when we would expect to see peak cormorant numbers,” Lawonn said. “That there’s no breeding activity on East Sand Island is extraordinary.”
Around 2,500 double-crested cormorants have been seen on East Sand Island this year, according to Jeffrey Henon, a spokesman for the U.S. Army Corps of Engineers.
The agency manages the island located at the mouth of the Columbia River, as well as the Caspian tern and double-crested cormorant colonies that nest there seasonally.
“The cormorants have begun constructing their nests, but we haven’t observed any eggs yet,” Henon said.
The agency began hazing and shooting double-crested cormorants and destroying eggs and nests on the island in 2015 to control the colony’s numbers. Cormorants dine on fish, in particular young salmon species.The Army Corps determined it was necessary to reduce the number of breeding pairs on East Sand Island from the more than 13,600 pairs in 2014 to about 5,600 by 2018 to protect fish.
The cormorant colony abandoned the island several times in 2016 and 2017, a dispersal the Army Corps blamed on predators, such as eagles, and that opponents of the agency’s management plan blamed on the Army Corps.
This year, the Army Corps has focused on modifying the terrain of East Sand Island to discourage mass nesting and maintain colony numbers at the target established in 2015.
“We have discouraged the few birds attempting to nest in the central portion of the island, which was previously the eastern area of the colony, with minimal hazing activity,” Henon said.
Eagles have been observed dispersing cormorants, he added.
Each year since hazing at East Sand Island began, the number of birds nesting at the Astoria Bridge has grown — a situation that could cause significant expense to the state Department of Transportation.
The state just finished repainting the bridge’s span in 2018, a lengthy and expensive process that caused routine traffic delays. More work is planned in 2021 on the under truss, where many of the cormorants now appear to be nesting.
The birds’ droppings are corrosive and reduce the life span of the bridge’s protective steel coating. State officials worry that if the birds continue to nest in such high numbers on the bridge, both the expense and the frequency of painting will increase.
It is too late in the year to haze the birds off the bridge, but, internally, the Department of Transportation is still looking at its options for next spring ahead of the 2021 work.
“We have not come up with a plan yet to address the cormorant problem,” said Lou Torres, a department spokesman. “We are currently working very closely with the Oregon Department of Fish and Wildlife on a variety of possible deterrents and tools that include hazing the birds.”
Rex Ziak, who lives in Washington state’s Pacific County, said he didn’t fully grasp the dilemma until last week, when he saw the nests for the first time while stuck in traffic.
Looking down, he had a perfect view of the structures undergirding the bridge and the cormorant kingdom.
He saw dozens and dozens of cormorants and nests full of eggs. He grabbed his wife’s phone and started taking pictures.
“It’s just like it awakened me to the dangerous situation that has occurred,” Ziak said. “Dangerous in terms of just the integrity of the bridge’s expensive paint job.”
One of his photos shows a nest full of eggs cozily tucked in a corner. A spray of white bird droppings surrounds the nest and obliterates the new, green paint.
The bridge cannot host an infinite number of cormorants, but Ziak, looking at all the eggs below him, kept thinking, “This problem is only just starting.”