Do We Know How Many Birds and Bats Are Killed by Wind Turbines per Year?

This question was supplied by the ‘Ask the Experts’ database managers.

Reviewed by: Dr. Scott McWilliams

Last Update: May 21st, 2020

The Ask the Experts database managers conducted an interview with Dr. Scott McWilliams (Professor of Wildlife Ecology & Physiology) to summarize the findings of multiple URI studies that have set out to minimize the effects that the Block Island Wind Farm has had on birds and bats.

According to Dr. McWilliams, the number of avian deaths related to offshore wind turbines is very small and that, to his knowledge, there have been no documented avian deaths directly associated with the Block Island Wind Farm. As for bats, though they are more vulnerable to being struck by offshore wind turbines than birds, there are very few bats in North America that fly off of the coast. So, at the moment, there is not a dire concern for the occurrence of bat collisions at the Block Island Wind Farm.

That being said, new technologies are currently being experimented with to monitor post-construction collisions at offshore wind sites. An example of this is the Thermal Animal Detection System (TADS) which was designed to monitor bird collisions with offshore wind turbines1. This and other monitoring technologies, such as the ThermalTracker Software and Acoustic & Thermographic Offshore Monitoring (ATOM) were discussed in a presentation given by the U.S. Department Of Energy Office Of Energy Efficiency & Renewable Energy. These technologies are each in various stages of development and testing; so, they have not yet been implemented on a regulatory scale. Read more about these developing technologies here.

On a local scale, URI researcher and professor Peter Paton is leading an ongoing study in which tracking arrays will be installed on up to two offshore wind turbine foundations at the Block Island Wind Farm to track several species of migratory birds and bats that have been fitted with nanotags from the dozens of other ongoing projects.

When asked how the effects of offshore turbines compare with that of onshore, McWilliams says that is the “apples and oranges comparison”. There are many documented negative effects correlated with onshore turbines, and, for both onshore and offshore, proper siting alongside pre-and-post-construction observations are important for avoiding any unnecessary impacts on birds and bats.

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