Cormorant Populations

For purposes of the Service's population-based take framework, cormorants in the contiguous 48 states are evaluated within four populations: Atlantic, Florida, Interior, and Western. These populations were delineated based on breeding and wintering distributions, subspecific taxonomy, and other information described in the Service's 2020 Final Environmental Impact Statement (FEIS).

The Service uses a Potential Take Limit (PTL) framework to evaluate and inform the authorization of lethal take of cormorants under migratory bird depredation permits. The framework is based on approaches described by Runge et al. (2004) and is described in detail in the November 20, 2020 FEIS.

A PTL represents the potential amount of annual take that may be authorized for a population while remaining within established biological and policy parameters. PTLs are population-specific and are informed by population size, population growth, and a management factor that reflects the Service's management objectives and risk tolerance. The Service uses PTLs as population-level limits when evaluating permit requests and determining how much take can be authorized.

The Service currently maintains population-specific PTLs for the Atlantic, Florida, Interior, and Western cormorant populations. PTLs are periodically evaluated and updated as new population information becomes available.

Potential Take Limits for Cormorant Populations in the Lower 48 States

Monitoring Protocol

The February 12, 2021 rule allows the take of up to 121,504 cormorants annually for certain purposes. To meet obligations under the MBTA, all Service actions must be compatible with the conservation of migratory species. Therefore, to allow this level of take, the Service must ensure the cormorant population data are sufficient to assess the cormorant populations in the future.

Federal, state, tribal, and many private entities share the Service’s goal of maintaining sustainable cormorant populations. Many of these entities conduct cormorant monitoring and contribute to ongoing research, as well as regional or local cormorant management efforts. However, to date, coordinated monitoring that embody shared objectives and standardized methods across the flyways does not exist. Heavily reflected within comments by states, tribes, nongovernment organizations, and members of the public during the 2020 rulemaking process was the desire to enhance existing monitoring efforts. Therefore, the Service committed to work in partnership with the flyways to develop a more coordinated monitoring program for each subpopulation of cormorants in order to improve subpopulation estimates of cormorant abundance.

Following the publication of the rule in 2021, the Service initiated a collaborative effort with all four flyways to address the need for coordinated cormorant monitoring. The resulting cross-flyway team includes individuals from each region of the Service, USDA Wildlife Services, and three representatives from each of the four flyways. The goal of the cross-flyway team was to conduct a thorough analysis of the problem (i.e., the objectives we want to achieve via a monitoring program) and to provide insight into what type of future monitoring might be needed. To do this, the cross-flyway team employed a Structured Decision Making (SDM) approach to identify specific flyway-based monitoring values, objectives, and monitoring alternatives with the potential to address the associated objectives. The resulting report describes the top-ranked monitoring objectives for the Service and each flyway.

While the cross-flyway team made significant progress towards characterizing important considerations related to the implementation of a large-scale monitoring program, monitoring strategies and objectives will require continued refinement over the next year from a broader group of stakeholders, budgetary decision makers, analysts, and divisions of state, tribal, and Canadian provincial fish and wildlife agencies within each flyway. Therefore, the final report describes a roadmap for next steps that need to occur in each year 2022 - 2026 to ensure this monitoring development effort will continue.

The final report provides an in-depth review of strategies for monitoring cormorants to ensure the data used to determine population abundance are adequate to assess the PTL model described in the 2020 FEIS. The potential monitoring strategies listed in the report are intended to serve as the basis for stakeholder meetings between the Service, the flyway councils, USDA Wildlife Services, and conservation partners across states and tribes in calendar year 2022. The Service and the cross-flyway team intend for this report to serve as an initial decision-support document for these entities to discuss and determine which strategy will best serve as an effective monitoring program for cormorant subpopulations. The Service intends to manage and support this iterative process with the goal of finalizing recommendations for monitoring after sufficient stakeholder input from each flyway. The report provides the following tools and analyses to assist in this decision-making process:

1. An assessment of existing monitoring efforts in each flyway;
2. Monitoring objectives for the Service;
3. Monitoring objectives for each flyway;
4. List of potential monitoring strategies;
5. Strengths, weaknesses, opportunities, and threats for identified potential monitoring strategies;
6. Framework for the Service to make informed policy decisions about allowable take in 2026 based on existing monitoring, and uncertainty about populations;
7. Information that enables states to assess tradeoffs of implementing a monitoring strategy; and
8. Roadmap of next steps to further engage with additional stakeholders following the 2022 winter flyway meetings.

U.S. Fish and Wildlife Service Final Report: Recommendations for Implementing a Monitoring Strategy for Double-crested Cormorant Subpopulations in the United States

The Service expresses appreciation to individuals from the cross-flyway team, USDA Wildlife Services, and the Association of Fish and Wildlife Agencies Bird and Fish Related Conflict Working Group who all willingly shared their time, expertise, and insight to develop the report.