Bird Displacement

Seabird Displacement and Collision Risks

Bird displacement by offshore wind energy
Image provided by the Schatz Center

Wind farm infrastructure is large- single floating 15-20 MW turbines can be 889-1110 feet off the water. All of the California wind farms will have multiple turbines. Seabirds transiting offshore wind operation areas may collide with wind farm infrastructure or may have habitat displaced by offshore wind farms. 

 

What birds are located offshore?

There are about 81 species of seabirds that spend their lives off the coast of California on the Outer Continental Shelf where wind projects are planned. Among the groups of seabirds are sea ducks, loons, grebes, procellariids (e.g. fulmars, petrels, shearwaters) comorants, phalaropes, jaegers, skuas,  alcids (murres, auklet),  gulls, and terns.  67 of these species are resident species that remain in California during the winter and non-breeding seasons. 21 of these species have large localized nesting populations of more than 600,000 individuals. Most of these birds forage on the food chain associated with the California Current. Birds use a variety of forage strategies including dipping, fluttering over the surface, plunging, underwater pursuit, seizing prey from the surface, or scavenging. 

What do we know about seabird interactions with offshore wind infrastructure? 

We do not have large amounts of information about the interactions between Pacific Ocean seabird and offshore infrastructure. Seabird collision rates are generally very low but birds may be impacted by offshore wind infrastructure particularly if there is artificial lighting on the infrastructure, bad weather, or low visibility conditions. In bad weather, it may make a difference whether a bird is a  “flapper” or a “glider”. A “flapper” is more likely than a “glider” to be able to change direction within a wind farm area.  It is uncertain whether seabirds are displaced from or attracted to offshore wind farms. [1] It appears to depend on the species of bird. Some seabirds learn to avoid wind farms (e.g. eiders). Birds that avoid wind energy areas may expend more energy to forage or migrate. Other species appear to be drawn to offshore wind infrastructure (e.g. gulls), possibly due to  a reef effect from species attracted to the turbine platforms.

One collision risk model found that species groups most vulnerable to collision with wind infrastructure include pelicans, terns,  medium and large gulls, and jaegers. [2]  

What is being done to address seabird collisions? 

The government requires that wind developers take measures to protect seabirds and bats from collisions. It is unlikely that any single deterrent method will work for all bird species within an area. There are two mitigation options. One option is during sensitive stages of a bird’s cycle such as migration, “passive curtailment” can be used to shut off turbines or change turbine speeds.  A second option is to install an “automatic detection system” that can either trigger a change in turbine activity or emit a visual or auditory alert signal to deter a high-risk collision. [3] It has not been possible to make a general conclusion about whether ADS systems are effective.

To avoid as many collisions as possible, wind developers will need to study their lease areas carefully to understand the foraging patterns and migratory routes of the  bird species. This may influence turbine spacing decisions to avoid impacts. For lights, the turbines and related infrastructure will need to have lights limited to safety, operations, and navigation that are focused to avoid spillover into the sky and water  especially during peak migration seasons or during seabird fledging times.[4] Blue or green intermittently flashing lights rather than red and white lights may attract fewer birds. 

Why does the Audubon Society support wind power when there is a potential for seabird collisions?

There are many causes of potentially avoidable bird deaths including collisions with building glass (at least 365 million), collisions with communication towners (at least 6.5 million), collisions with electrical lines (at least 8 million), collisions with vehicles (at least 89 million), collisions with land-based wind turbines (at least 140,438), oil pits, (at least 500,000), and cats (at least 1.4 billion). [4]

The Audubon Society supports responsibly sited renewable energy to meet U.S. energy needs. The Audubon society is concerned that failure to stabilize carbon emissions and hold warming to 1.5 degrees Celsius above pre-industrial levels may result in the extinction of more than 350 North American bird species. [6] Marine heatwaves with linkages to climate warming have been linked to loss of seabirds including five mass mortality events. [7] 

What data gaps do we have?

Current data gaps associated with the particular California projects include understanding the interaction of specific bird species with the wind farms. More information is needed about potential displacement of  overwintering Scripp’s murrelet, overwintering Guadalupe murrelets, overwintering Craveri’s murrelets, and endemic Ashy Storm-Petrels in the Central Coast.  More information is needed about displacement associated with breeding Leach’s Storm-Petrels and Common Murres in the vicinity of Humboldt Bay. In both are, more information is needed about the collision vulnerability for migratory jaegers, terns, and gulls as well as pink-footed shearwater and albatrosses travelling through wind farm areas. [8]

Groups such as the US Geological Survey are collecting aerial seabird and marine mammals surveys to address these data gaps. 

References
  1. Dierschke, V., Furness, R.; Garthe, S. (2016). Seabirds and Offshore Wind Farms in European Waters: Avoidance and Attraction. Biological Conservation, 202, 59-68. https://doi.org/10.1016/j.biocon.2016.08.016
  2. Kelsey, E.C. et al  (2018)  Collision and Displacement Vulnerability to Offshore Wind  Energy Infrastructure Among Marine Birds of the Pacific Outer Continental Shelf, Journal of Environmental Management: 227 (Data based on percentage of time flying a night vs. day, percentage of time spent in a rotor-swept zone based on flight height)
  3. Ballester, C., Dupont, S., et al. (2024) A Standardized Protocol for Assessing the Performance of Automatic Detection Systems Used in Onshore Wind Power Plants to Reduce Avian Mortality 
  4. U.S. Fish and Wildlife Service, Bird-conscious Lighting for Vessels & Offshore Structure Informative Guide, https://www.fws.gov/media/bird-conscious-lighting-vessels-offshore-structures-informative-guide-printablepdf 
  5. U.S. Fish and Wildlife Service, Threats to Birds, Top Threats to Birds (U.S. only, ordered by Mediate Estimate of Bird Mortality Annually as of 2017) https://www.fws.gov/library/collections/threats-birds 
  6. Survival by Degrees: 389 Bird Species on the Brink, https://www.audubon.org/climate/survivalbydegrees
  7. Jones, T. Parrish, J.; Lindsey J. et al. (2023) Marine bird mass mortality events as an indicator of the impacts of ocean warming. Mar Ecol Prog Ser :HEATav8. https://doi.org/10.3354/meps14330
  8. Adams, J, Felis, J. Kelsey, E., and White L. (2023) Marine Birds of the California Current and Studies to Inform Offshore Renewable Energy, Presentation to California Coastal Commission, https://documents.coastal.ca.gov/assets/upcoming-projects/offshore-wind/Th4/Th4-Adams.pdf 
  9. USGS, Western Ecological Research Center, Aerial Seabird and Marine Mammals Surveys, https://www.usgs.gov/centers/werc/science/aerial-seabird-and-marine-mammal-surveys#overview