Cormorant Management on Egret Island, Pelican Lake, Ashby, MN

What is the history, importance and ownership of Egret Island?

Egret Island on Pelican Lake in Grant County supports one of the largest colonies of double-crested cormorants (cormorants) in Minnesota. The island also provides nesting habitat for the American white pelican, great blue heron, and several other colonial waterbird species, including species in greatest conservation need. The island was gifted by The Nature Conservancy to the DNR Scientific and Natural Areas (SNA) Program in 2007. The island has been managed as a bird sanctuary and is closed to the public from April 1 – July 15 each year to protect nesting birds. Bird watchers and photographers can enjoy the area by boat throughout the year, including during seasonal closure.

The DNR discovered that a Commissioner’s Designation Order was never completed for this site, so the land is considered DNR Forestry land by statute and does not currently have the same protections as designated SNAs. Designated SNAs do not allow the use of firearms unless authorized by a designation order. Amendments to designation orders require a public hearing. Though not yet officially designated as an SNA, Egret Island is managed by the DNR as an SNA. DNR will continue to honor the proposed status of the island while working toward the official designation.

What concerns led to the decision to consider lethal cormorant control on Egret Island?

The most recent fisheries survey on Pelican Lake, near Ashby, Minnesota indicates that cormorants may be limiting survival of young walleyes that are key to sustaining a healthy walleye population. The June 2021 survey showed a decline in the walleye population, with a survey gillnet catch rate near a historical low. The 2021 survey and additional analysis indicated changes from previous surveys.

Public concerns regarding cormorant colony expansion and the potential impact on the Pelican Lake walleye fishery began in the early to mid-2000s. The DNR acknowledged the concerns but determined that control efforts were not warranted at that time because DNR netting results were near or above the management objectives defined in the Pelican Lake Fisheries Management Plan.

Metrics measured in the walleye population in Pelican Lake are now similar to those of other walleye populations responding to elevated cormorant predation. The DNR assessed multiple factors that could affect walleyes and determined that the most likely explanation for the walleye pattern observed was that the population of cormorants nesting on Egret Island is limiting survival of young (one- and two-year-old) walleyes, which are the preferred size for cormorant feeding.

The DNR’s current preferred alternative would be to employ lethal measures to remove a portion of the growing double-crested cormorant population on Egret Island. The DNR considered seven alternatives and worked with USDA-Wildlife Services on management options. Several alternatives are not practical or not likely to be effective (e.g., hazing/harassment, tree removal, ceramic eggs, egg oiling). The DNR is considering three remaining alternatives: revising fish management goals, increasing survey efforts to increase understanding of the system, and lethal control of adult birds.

What agencies have the authority to manage and control cormorants if they are causing damage?

The DNR has responsibilities to manage fisheries in Pelican Lake and wildlife on Egret Island. The cormorant is not protected under Minnesota statute but is federally protected by the Migratory Bird Treaty Act. This act prohibits killing cormorants, their eggs or young and prohibits the disturbance of the nests or young, except as provided for by the United States Fish and Wildlife Service (USFWS) through the federal special double-crested cormorant permit.

Lethal control of cormorants on Egret Island requires a permit from USFWS. Permits to control cormorants to protect wild and stocked public fisheries are issued only to state and tribal resource managing agencies. Applications need to be submitted at least a month before control efforts are initiated. Cormorant management options must minimize disruption to other bird species nesting nearby, which are protected by state and federal laws. Control of cormorants may be required annually, depending on how the cormorant population and walleye fishery respond to management. Any subsequent permits and associated control will be determined by monitoring both the fishery and the waterbirds using the island.

When would control efforts begin and how is it accomplished?

If lethal controls are pursued, they would be completed by the United States Department of Agriculture-Wildlife Services (USDA-Wildlife Services) shortly after ice-out in early spring. USDA-Wildlife Services controls birds using lead-based ammunition, to minimize wounding rates and the potential for wounded birds to leave the island. Control will occur on the island using suppressed .22 caliber rifles and on a single day to minimize bird behavioral disruption. It may still be disruptive to people using the lake. Any off-island control would be accomplished with non-lead shotgun ammunition. Carcasses would be removed from the island and disposed of in a landfill.

Lead ammunition would likely be used for lethal control of cormorants in 2024. The DNR explored non-lead ammunition alternatives in recognition of lead toxicity. The 60-grain sub-sonic lead .22 caliber ammunition that USDA-Wildlife Services has been using in colony settings for lethal cormorant control offers the most reasonable balance between safety and effectiveness. The DNR will continue to look for alternatives to lead ammunition.

How will the control effort be monitored and evaluated?

This system is complex and multiple factors may be affecting the population levels of both birds and fish. If control occurs, additional surveys will be needed to assess cormorant abundance. Fish surveys would occur on a more frequent basis than in the past, to measure the response of the walleye fishery to the reduction in cormorant predation. Surveys to understand the impacts of cormorant control on other birds nesting on the island may also be needed.

What are the costs of control and who will pay for it?

Contracted cormorant control can be expensive and may be required annually depending on how the cormorant population and walleye fishery responds to management. Lethal control would cost $10,000 per day minimum; one day of lethal control is anticipated for Pelican Lake. The DNR would need to conduct additional fish and waterbird surveys on Pelican Lake, supply data analysis and future permit applications. DNR funding to conduct control is limited, as is staff time for this work. There are several options for funding that will need to be considered if control is conducted.