Wind power takes a toll on migratory bats
But learning bat migration patterns may save them from wind turbines
September 12, 2007
One fact is that the most affected bats are migratory species. These species make large seasonal migrations and spend the rest of their time roosting in trees. It is during the migrations that they are vulnerable.
Little is known about such migrations, but to glean information into why such bats are vulnerable to wind turbines and what might be done to safeguard them, two scientists, Paul Cryan and Adam Brown, recently studied migration patterns of the Hoary bat to Southeast Farallon Island, a small island off the coast of the San Francisco County.
Hoary bat. Photo by Paul Cryan.
More studies will be needed before solutions can be implemented, however. As Mr. Cryan states, "Unfortunately, I don't think that anybody is in a position yet to make reasonable recommendations for reducing the number of fatalities. We just don't know enough about why bats are colliding with turbines." Mr. Cryan sees the need for further studies in three places if scientists are to achieve a breakthrough:
1) A more comprehensive picture of wind turbines is necessary, since researchers "currently have information on bats from about 10% of the existing wind energy facilities in the U.S. and Canada. We have very little information from states like Texas, New Mexico, and California where bat diversity is highest and turbines are being built in large numbers." To achieve this researchers "need to the trust and cooperation of the wind industry".
2) Further information on migration routes and times may be essential: "we need to learn how to predict if certain sites will be likely to kill bats before turbines are built and also to predict when bats are most likely to be killed at existing wind facilities."
3) Finally, studies need to be undertaken as to why bats collide with turbines in the first place. Mr Cryan points out that "there is a growing body of evidence that suggests bats are attracted to wind turbines." He is "hopeful that if we can figure out what it is that is attracting them, we can somehow eliminate the attractant."
CITATION: Paul M. Cyran and Adam C. Brown (2007). Migration of bats past a remote island offers clues toward the problem of bat fatalities at wind turbines Biological Conservation, Issue 139, I-II