Cormorants facing possible death by shotgun blast at their colony near the mouth of the Columbia River don’t seem to have started house-hunting in less dangerous neighborhoods farther down the coast.
But as the Oregon Department of Fish and Wildlife once again prepares to coordinate nonlethal hazing projects at various Oregon estuaries this spring, biologists will watch for changes in cormorant colonies south of the river.
The U.S. Army Corps of Engineers, which manages the massive double-crested cormorant colony on East Sand Island, began a culling program in 2015 in an effort to manage the growing colony and reduce the number of young salmon the birds were estimated to consume annually. That year, the Army Corps’ contractors killed a total of 2,346 adult birds and oiled eggs — a process that prevents the eggs from hatching — in 5,089 nests. In 2016, the Corps reported a total of 2,982 adult birds killed.
So far there haven’t been any changes in populations elsewhere that state biologists can directly attribute to management activities on East Sand Island. Drawing a straight line from the Columbia River estuary to changing cormorant populations farther down the coast is difficult to do anyway.
“If we do see increases at the Oregon Coast colonies, we would be curious to know how this might be related to activities on the Columbia River,” said state biologist and avian predation coordinator James Lawonn. But, he added, “cormorant colonies naturally fluctuate quite a bit.”
The Department of Fish and Wildlife already monitors double-crested cormorant populations on the coast extensively. In addition to regular nonlethal hazing activities, when some monitoring can occur, there are regular aerial surveys and estuary surveys. On these excursions, biologists focus on a variety of bird species but also take note of the double-crested cormorants.
The state has not increased any of its monitoring activities in response to the Corps’ lethal management plan on East Sand Island. This is mostly because the Department of Fish and Wildlife’s own monitoring efforts along the coast and in the estuaries are already “pretty robust,” Lawonn said. “We feel that we’ve got our bases covered.”
Oregon plans to begin its nonlethal hazing activities in May, focusing on the Nehalem, Nestucca and Coquille river estuaries and Tillamook and Alsea bays before moving up to the Lower Columbia River area.
The cormorants are native to Oregon and are particularly prevalent on the state’s estuaries from April through October, according to a news release from the Department of Fish and Wildlife — overlapping with when wild-spawned and hatchery salmon juveniles are migrating from their origin streams to the ocean.
The hazing activities by the state are an effort to protect, in particular, spring migrants that are considered threatened under the Endangered Species Act. Though some small pyrotechnics might be used, most often the state’s hazing techniques take the form of people driving around in boats, chasing cormorants away from areas where vulnerable — and valuable — juvenile salmon are concentrated.
The Department of Fish and Wildlife has coordinated this cormorant hazing project for the last eight years, and such nonlethal hazing in one form or another has occurred at some Oregon estuaries since the late 1980s.