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Due To Low Numbers Of Estuary Cormorants Showing Nesting Activity, Culling Remains Suspended
Posted on Friday, August 11, 2017 (PST)

As many as 19,000 double-breasted and pelagic cormorants are hanging out at East Sand Island, a tiny dredge spoil island in the lower Columbia River estuary, as of the end of July. Some are mating but only about 500 are exhibiting nesting behaviors, far fewer at this time of year than is normal.


That’s why culling, harassing and egg oiling of the birds and their nests was suspended by Wildlife Services, the U.S. Army Corps of Engineers’ contractor, April 27, after just 248 birds were shot, and has not resumed because the cormorants have yet to settle down to significant nesting activity.


The Corps has said that as many as 40 eagles harassed the sea birds in June, keeping them from nesting on the island and driving them to other areas, such as local bridges, Willapa Bay and Grays Harbor.


This is the third year of culling for the Corps and the second year in a row that the birds have been late to nesting, requiring the Corps to suspend its operations designed to reduce the number of breeding pairs in the lower river. Cormorants feed on juvenile salmon and steelhead, some of which are listed under the federal Endangered Species Act.


Last year culling was suspended in mid-May and Wildlife Services didn’t resume until October 3. By mid-July last year some 15,300 cormorants were seen “loafing” on the island. By August about 23,000 were on the island and by September many were rebuilding nests and laying eggs. Still, the agency managed to cull nearly 3,000 of the cormorants in 2016, almost all of those by the end of October.


(See CBB, October 14, 2016, “Cormorant Culling From Boats Resumes In Lower Columbia Estuary, Will Continue Through October,”


Yet the Corps is hesitant for now in saying that its cormorant management program has led to a possible collapse of what may have been the largest cormorant colony in the world, nor is it certain whether culling could resume this year, as it did last year.


“Given our recent observations of what appear to be nesting attempts, we cannot say that the colony has ‘collapsed’ for this season,” said Corps spokesperson Karim Delgado. “We are waiting for further information from our field crew and coordination with the adaptive management team — including biologists with USFWS — before drawing conclusions about the fate of the colony, the ongoing breeding season and potential management actions later this year.


“As detailed in our management plan, we are continually adapting our management actions to the best and most current information available to us. We are as interested as the rest of the public in understanding how the recent nest attempts will develop for the remainder of the breeding season.”


The Audubon Society of Portland disagrees and has for two years now claimed that the double-crested cormorant colony is collapsing.


The organization sent a letter in June to the U.S. Fish and Wildlife Service, which has issued three annual predation permits to the Corps, urging the Service to withdraw the permit and terminate the project.


The Service’s response said it is aware of what is happening with the cormorants in the estuary and is working with the Corps to monitor and manage the situation.


(See CBB, July 7, 2017, “Corps Continues Suspension Of Culling Salmon-Eating Cormorants In Estuary,”


The program to cull and oil nests, as well has other hazing activities to otherwise discourage the presence of cormorants in the lower Columbia River estuary is designed to protect migrating threatened and endangered salmon and steelhead smolts by reducing the cormorant population that feed upon them. It is an action called for by reasonable and prudent alternative 46 of the 2014 biological opinion for Columbia River salmon and steelhead.


The Corps’ goal is a double-crested cormorant colony size that represents an acceptable level of predation on juvenile salmonids and a more balanced ecosystem overall, Delgado said.


“Success is determined by our ability to support a localized colony of double-crested cormorants while minimizing the potential for expansion to levels that would hurt the chances of survival for salmonids protected under the Endangered Species Act,” he said.


That would mean a cormorant colony at East Sand Island of between 5,380 and 5,939 breeding pairs, while modifying the island so that it would support the smaller colony.


However, the recovery to a breeding colony is slow this year.


In late June, about 12 bald eagles were present and about 7,000 to 9,000 birds clustered along the shoreline, according to the Corps’ June 26 – 30 report. Some 3,500 cormorants were also seen on the Astoria-Megler Bridge, with 722 nests. The Lewis & Clark Bridge that crosses the Youngs River in Astoria had 125 nests with chicks ranging from 10 to 30 days old.


The Corps’ July 3 – 7 report found only 2,000 to 3,000 cormorants on the island and the Astoria-Megler Bridge had about 7,000 birds and an additional 47nests, bringing the total to 769 nests on the bridge. The chicks were 35 to 40 days old.


The count on East Sand Island July 10 rose slightly to 3,000 to 3,500 cormorants. The bridge had 6,000 adults and 834 nests, according to the July 10 – 14 report.


The count on the island was about 6,000 cormorants on July 19 and rose to about 6,500 July 21. About 500 double-breasted and 1,200 Brandt’s cormorants displayed breeding behavior. Four bald eagles were seen in the area, but only one near the island.


The number of nests on the Astoria-Megler Bridge dropped to 787. “Nest observations show chicks with asynchronous age structures, with some birds very young and downy, while others are mobile and ready to fledge,” the weekly report said. Some 147 nests were seen on the Lewis & Clark Bridge.


During the last week of July the number of cormorants on the island rose to 19,700 and many were nest building nests (about 500) and breeding. No eagles were seen.


A survey at the Astoria-Megler Bridge counted about 4,500 to 5,000 cormorants roosting on the bridge the evening of July 23. During that evening and the following morning observers saw double-crested cormorants “commuting to the bridge mostly from downstream and most birds departed the bridge in the morning and moved downstream.” Nest numbers dropped to 654 active nests.


The Corps’ cormorant management timeline is at


Also see:


-CBB, June 16, 2017, “With Cormorant Nesting On East Sand Island Stalled, Boat-Based Shooting Of Birds Suspended,”


--CBB, April 28, 2017, “Third Year Of Shooting Salmon-Eating Cormorants, Oiling Nests: Goal Is To Kill 2,409 Birds,”


-- CBB, September 9, 2016, “Court Allows Continued Culling Of Cormorants In Columbia Estuary To Reduce Predation On Salmonids,”


--CBB, August 5, 2016, “Court Hears Oral Arguments On Killing Estuary Cormorants To Protect Juvenile Salmonids,”


--CBB, July 1, 2016, “Plaintiffs Press Case Against Cormorant Culling In Court; 2,394 Birds Shot So Far This Year,”


--CBB, June 17, 2016, “Is Salmon/Steelhead BiOp Driving Cormorant Culling? Not Necessarily Says Corps”


--CBB, June 2, 2016, “Estuary Cormorants Abandon Nest, Eggs After 'Significant Disturbance;' Audubon Blames Feds' Hazing,”


--CBB, May 13, 2016, “Corps More Than Two-Thirds Complete In Killing Over 3,000 Estuary Salmonid-Eating Cormorants,”


--CBB, April 1, 2016, “For Second Year, Corps Issued Permit To Cull Cormorants In Lower Columbia; Allows Killing 3,216 Birds,”


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