Monday, August 29, 2011

Things that kill birds, other than wind turbines



An article in the Washington Post today discusses estimates of the number of birds killed by wind turbines. This article is interesting for putting the bird kill in some context. The article presents estimates from the American Bird Conservancy on the number of birds killed by different human-related causes, with house cats (several hundred million per year) and window glass (100 million per year) the leading ones. The estimates for wind turbine deaths are three orders of magnitude smaller (150 thousand to 500 thousand estimated by different parties.) An estimate of the total North American bird population would allow a mortality estimate. A quick scan of this table suggests that the total bird population in North America is several billion. The mortality rate attributable to wind turbines, even using the high estimate, would be less than one tenth of one percent. And habitat destruction may be the leading threat to species survival.

Of course, not all birds are created equal. Turbines killing off urban pigeons or European starlings* might be considered an environmental benefit. A turbine with high mortality for an endangered species would be a concern. The article is presenting the context at the behest of an industry association after six golden eagles were killed, most likely by wind turbines.

In the end, no energy source is free, and all the costs and benefits of alternative sources must be compared. If additional wind turbines displace a new natural gas electricity plant, those options can be compared. If additional wind turbines can displace an existing coal plant, then a different set of costs can be compared. Accurate pricing of the environmental harms from coal and natural gas via fuel-specific taxes would help to make the decision easier. I suppose a bird mortality tax could even be developed for wind turbines.

*Full disclosure: several years ago a bamboo thicket by my townhouse was infested by several hundred European starlings (a non-native, invasive species) that roosted every night around sunset. They made noise all night long and their droppings produced an odor even worse than that of the nearby Dumpster. We did not benefit from their consumption of insects, because they spent the active day elsewhere. We finally chased them away by making lots of noise every evening as they came in to roost. After several days of our annoyance the entire colony relocated as one.

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