in comparison, domestic cats kill some 2,000,000,000 birds/year in the usa (ok, that's an exaggeration, see below).
but who's counting
on edit: here's some actual information:
The often-cited worst case for windmills is Altamont Pass in California where many hawks and eagles have been killed. But even at Altamont, an early windmill location with technology and turbine proximity judged inappropriate today, the Center for Biological Diversity's lawsuit against its operators states: "We are not suggesting closing the Altamont wind farms, rather that turbine owners take reasonable measures to reduce bird kills and adequately compensate for impacts to imperiled bird populations."
Fortunately birds simply avoid the blades of the newer wind turbines.
who'd ever thunk it that birds aren't completely stupid? Studies at more recently designed wind farms tell us that bird mortality at windmills is very low. A summary indicates that the average number of birds killed annually across North America is between one and two per turbine. Arguably the best of the intensive studies was carried out by Canadian Ross James. His year-long field work at a Toronto wind turbine sited in the middle of a fall migration route turned up three birds killed. He also watched birds change course to avoid the turbine blades, an observation shared by many other observers. His final conclusion: "The greatest threat to all wildlife is still loss and/or degradation of habitat."
Against this data we have scare statements like one from a dedicated hawk-watcher in the Chautauqua town of Ripley: "If a bird doesn't get killed in Ripley, he may get killed in Rochester, if not there then at Derby Hill, Prince Edward Island, Toronto...." Statements like this together with intensive lobbying by such deeply concerned birders is deterring the development of wind farms.
But consider what development at Ripley would mean. Over 20,000 hawks, vultures and eagles pass that location each spring to say nothing of passerine migrants. If 35 wind turbines were erected there (more than the number contemplated), the national average would suggest annual deaths of about 60 birds of all species, an infinitesimal fraction of the total number traversing that region.
http://www.acsu.buffalo.edu/~insrisg/nature/nw04/0509Windmills.htmand now to the catshttp://www.mammal.org.uk/catkills.htmThe Mammal Society has just completed a survey of the kinds and numbers of animals that are killed by domestic cats. Michael Woods has produced a summary of the results of the survey which ran for the 5 months up to August 31 1997.
We received the kill or capture records of 964 cats, amounting to more than 14,000 prey items. The mean number of catches or kills per cat over the five month period was 16.7 which gives an annual average per cat of 40 victims. Multiplying the pet industry's estimate of 7.5 million domestic cats by 40 suggests that
the British cat population could be killing at least 300 million animals and birds every year.
http://www.acsu.buffalo.edu/~insrisg/nature/nw98/cats.htmlEstimates of the number of birds killed annually by the 40 million North American domestic cats allowed outside range from a conservative 55 million
to well over a billion.