Bat Fatalities at Wind Energy Turbines Offer New Insight into Bat Migration

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After visiting Carslbad Caverns with my daughters this spring, I have a new affinity and respect for bats and their migrations. (In truth, I’ve always been a fan of bats, but more so even now.) So this recent update from the Journal of Mammalogy strikes a chord:


Bat fatalities at wind energy turbines offer new insight into bat migration

New data suggest that bats, like birds, may follow specifically defined routes when migrating rather than simply migrating in a dispersed way across a broad area. Wind energy turbines located in these routes may cause fatalities of migrating bats. As new sources of energy such as wind farms are being built in greater numbers, their impact on other aspects of the environment must be considered. While we reduce carbon emissions and develop renewable energy resources, we must be careful not to endanger migrating species such as bats.

The migratory behavior of bats, a topic that has received little attention in the past, is the subject of new study in the December 2009 issue of The Journal of Mammalogy. Wind turbines have been the cause of many bat fatalities, but these installations also offer a new opportunity to examine bat migration habits. This is because the majority of bat fatalities caused by wind turbines around the world have involved migratory bats during fall migration.

Over a period of seven years, scientists used acoustic monitoring and carcass searches at nine wind energy facilities across southern Alberta, Canada, to determine if bat activity and fatality were concentrated in certain areas or evenly distributed across the landscape. Their findings indicate that as bats migrated, they concentrated along selected routes at night and sought daytime roosting sites. Migratory tree-roosting bats, including hoary bats, eastern red bats, and silver-haired bats, are the North American species most affected by wind farms.

As locations and types of turbines are planned for new wind energy facilities, the information gained from studying the migratory habits of bats can be put to use, making the facilities even more environmentally friendly. For instance, the researchers found that greater tower height increased the probability of bat fatality, but that differences among sites in migratory bat activity also were related to the number of bat fatalities. By identifying migratory routes and the specific landscape features that bats follow, bat fatalities could be minimized by building wind facilities in areas with low migratory activity.

The full text of this article, “Geographic Variation in Activity and Fatality of Migratory Bats at Wind Energy Facilities,” The Journal of Mammalogy, Vol. 90, No. 6, December 2009, is available at


About the Journal of Mammalogy

The Journal of Mammalogy, the flagship publication of the American Society of Mammalogists, is produced six times per year. A highly respected scientific journal, it details the latest research in the science of mammalogy and was recently named one of the top 100 most influential journals of biology and medicine in the last century by the Special Libraries Association. For more information, visit

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