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Corps Issues Draft Plan To Curtail Nesting Of Burgeoning Salmon-Consuming Cormorant Colony
Posted on Friday, February 03, 2012 (PST)

Interested parties can now comment on a plan to “dissuade” nesting of yet another salmon-eating bird species on a portion the lower Columbia River’s East Sand Island, which in recent years has become what is believed to be the United States’ largest double-crested cormorant colony.


The U.S. Army Corps of Engineers in a draft environmental assessment released today proposes to construct an 8-foot-tall privacy fence across the island’s cormorant colony and use human presence and hazing as a means of discouraging nesting on a portion of the site.


The idea of the planned experiment is to determine if such dissuasion can be used successfully to urge up to 62 percent of the cormorants that nest each spring on the island to relocate.


Interested parties have until March 3 to submit comments on the plan.


The research results will help formulate long-term solutions for reducing the number of cormorants that nest at the site, and as a result reduce the species’ consumption of juvenile salmonids in the Columbia River estuary.


In 2011, the double-crested cormorant colony at East Sand Island consumed an estimated 22.6 million out-migrating juvenile salmonids. That consumption includes wild fish from 13 stocks of salmon that are listed under the Endangered Species Act.


The draft EA, called “Double-crested Cormorant Dissuasion Research on East Sand Island in the Columbia River Estuary,” can be found at:


The draft EA also addresses continuation of ongoing diet and fish consumption studies of the cormorant colony at East Sand.


A long-term management plan is currently being written by a multi-agency working group to help guide the Corps’ Portland District in developing effective alternatives to reduce salmonid consumption by the cormorant colony at East Sand Island.


The draft management plan titled, “Double-crested Cormorant Management to Reduce Predation on Juvenile Salmonids in the Columbia River Estuary,” is expected to be available for public review by May 2012. An end result of that process would be an environmental impact statement under the National Environmental Policy Act.


The plan is necessary to comply with NOAA Fisheries 2008/2010 Federal Columbia River Power System biological opinion. The BiOp’s “reasonable and prudent alternatives” include measures intended to improve survival of salmon and steelhead. RPAs specifically call out the need to develop and implement a cormorant management plan aimed at reducing the birds’ impact.


The DEIS is being developed in coordination with the U.S. Fish and Wildlife Service, NOAA Fisheries Service, states, tribes and other parties.


Anticipated DEIS follows the NEPA path taken earlier for Caspian terns. That management plan calls for the relocation of a large portion of the terns from the island they share with the cormorants. The Corps has over the past three years built a total of eight new islands as alterative nesting sites, and work is ongoing to attract terns to those sites. Five of the sites are in interior Oregon and three are in the upper Klamath region in northeastern California.


The draft EA released this week addresses research proposed for this year, including the nesting area fencing and hazing. The proposed actions of the draft EA are needed to better refine alternatives for a double-crested cormorant management plan and to provide information that might be useful to the adaptive management plan, a secondary, important outcome of the cormorant management plan.


The cormorants typically begin arriving in the estuary in mid-spring.


Double-crested cormorants were first documented to nest on East Sand Island in the Columbia River estuary in 1989. Since then, their numbers have increased from less than 100 breeding pairs to a peak of 13,770 pairs in 2007, the largest recorded cormorant colony in the western population and possibly all of North America, according to the Corps’ EA.


Concerns about impacts to salmon have been rising right along with that burgeoning colony size.


The privacy fence will be constructed this year prior to the cormorant breeding season and will act as a visual barrier to separate the easternmost 62 percent of the 2010 nesting area (ca. 8,400 nests) from the remaining core colony area.


During a mini-test of the concept last year, 15 percent of the area was walled off. Most of the hazed birds hopped the fence to do their nesting. Other dissuasion techniques have been tested at relatively small scales since 2008.


Nesting habitat on East Sand Island is not limiting, thus most hazed birds will likely attempt to nest elsewhere on the island, the draft EA says.


The west end of the island above normal high water is approximately 16.9 acres. During the 2010 nesting season, at total of 13,600 pairs of double-crested cormorants at East Sand Island occupied 2.6 acres, in 2011, 13,000 pairs occupied 2.8 acres. Even though the proposed privacy fence will be located to dissuade 62 percent of the 2010 nesting colony, the habitat west of the fence where no dissuasion will take place is 11.1 acres.


Hazed birds that relocate to nest west of the privacy fence alongside already nesting individuals could be exposed to more bald eagle disturbance and associated gull nest robbing. In past years, bald eagle and gull disturbance has been more frequent on the west side of the colony compared to the east end of the colony, the EA says.


Double-crested cormorants have a much higher tolerance to eagle predation then species like Caspian terns. Increased nesting density in the unhazed area (resulting from displaced cormorants joining those cormorants with a history of nesting in that area) however, could offer individuals more protection from predators.


Hazed birds that disperse from East Sand might 1) attempt to nest at an established colony site, 2) attempt to nest at a new colony site, or 3) not attempt to nest in 2012.


Questions or comments about the draft EA can be directed to Paul Schmidt, Environmental Resources Branch, (503) 808-4772, or via e-mail at or at the address below.


Mailed comments on this notice must be postmarked no later than March 3 and sent to:

District Engineer

U.S. Army Corps of Engineer District, Portland

Attn: CENWP-PM-E/Paul Schmidt

P.O. Box 2946

Portland, Oregon 97208-2946


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