Seabird Vulnerability Assessment for Renewable Energy Projects

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The WERC seabird studies team has developed a new framework for quantifying seabird species vulnerability to wind infrastructure in the California Current region of the Pacific Outer Continental Shelf. This tool supports marine resource-use planning by identifying sites where seabirds are most vulnerable and predicts how different species may be affected by wind-energy infrastructure.

Figure showing Pacific coast, a wind turbine, and identifying 3 ways birds may be affected by wind turbines

The WERC seabird studies team has devised a framework to quantify, compare, and map three types of vulnerability to offshore wind energy infrastructure for Pacific coast species.

Seabirds and Offshore Energy Development

Offshore wind energy development is a promising alternative energy source for coastal communities in the Western United States. The U.S. Bureau of Ocean Energy Management (BOEM) has recently considered renewable energy proposals within U.S. Pacific Outer Continental Shelf (POCS) waters off the coast of Oregon and California. Minimizing negative interactions of offshore wind energy infrastructure with marine species is an important step towards a sustainable offshore energy future.

Seabirds are among the most threatened groups of birds, due in part to their exposure to cumulative anthropogenic threats, including fisheries bycatch, pollution, habitat loss, and invasive species at terrestrial nesting grounds. The construction of offshore wind energy could pose additional threats for seabirds including collision with infrastructure and/or displacement from important foraging hot-spots, resting habitats, and migration corridors.

 

Quantifying Seabird Vulnerability, Species by Species

Because the POCS is home to so many different bird species that may respond to wind energy infrastructure in different ways, applying seabird data for marine planning is challenging. The WERC seabird studies team evaluated several previous assessment in the Atlantic and devised a framework to quantify and compare seabird vulnerability information and then used this framework to quantify vulnerability for 81 species in the POCS. The framework is designed to easily incorporate new seabird data as these become available.

Figure showing different types of vulnerability to wind energy by species

Population Vulnerability vs. Collision Vulnerability (A) and Population Vulnerability vs. Displacement Vulnerability  (B) for 81 marine bird species in the POCS.  Species with highest percent ranks are Ashy Storm-Petrel (gray) and Brown Pelican (orange). 

 

For each species, the team calculated three different vulnerability values:

  • Population vulnerability: vulnerability due to demographic factors, like population size and breeding rates, and global distribution. Endangered or threatened species, endemic species, and species with small population sizes score the highest on this measure, while highly migratory species that spend little time in the target area or have large population sizes score low.
     
  • Collision vulnerability: vulnerability to physical collisions with wind turbines. Species that spend a lot of time in the air, especially at heights where they may interact with turbine rotors, have high collision vulnerability. Species that are either attracted to the turbines (e.g. for roosting) or do not show avoidance behavior around wind farms also score high on this measure.
     

  • Displacement vulnerability: vulnerability due to habitat loss when offshore wind infrastructure is installed. Species that tend to avoid the area when infrastructure is installed or that have strict habitat requirements score the highest on displacement vulnerability.

 

To calculate each value, the researchers chose several factors that could be scored on a scale of 1 to 5 using information from the scientific literature. For example, to calculate displacement vulnerability, they searched for information on avoidance behavior and habitat flexibility. Species with turbine avoidance rates of 0–5% would get a 1 on this measure, while those with 6–17% avoidance would get a 2 and so on, with a maximum score of 5. Species that used a wide range of habitats and feed on many types of prey would get a 1 for habitat flexibility, while species with very specific habitat and prey requirements would get a 5. The researchers then combined these ratings into a single displacement vulnerability value.

The vulnerability values generated in this assessment can be used by resource managers to evaluate potential impacts associated with the construction and long-term operation of OWEI within the POCS. By comparing these values among species, managers can identify whichspecies are most at risk, and in what ways, making it easier to devise strategies to protect species of concern. By combining vulnerability values with species distribution data, researchers and managers can create maps of where marine species vulnerability is highest, information that can be used to evaluate environmental risks at potential new sites for offshore wind energy.

 

Vulnerability densitities mapped along the southern California coast, with the highest vulnerability close to shore

Vulnerability values can be combined with species distribution data to map vulnerability. This map shows how collision vulnerability and displacement vulnerability vary along the southern California coast, based on data from 81 species.

 

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