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Wind Turbines at the Altamont Pass in California, kill an average of 67 Golden Eagles per year. - Ajax

How about a bit o' perspective?

Here's a useful chart and additional information:

Window strikes – estimated to kill 97 to 976 million birds/year – Millions of houses and buildings, with their billions of windows, pose a significant threat to birds. Birds see the natural habitat mirrored in the glass and fly directly into the window, causing injury and, in 50% or more of the cases, death.

Communication towers – estimates of bird kills are impossible to make because of the lack of data, but totals could easily be over 5 million birds/year, and possibly as many as 50 million. Towers have proliferated in recent years, with an estimated 5000 new towers erected per year during the 1990s, mainly for the cell phone and digital TV industries. Any tall structure will kill birds by collision, and lighted towers attract birds at night.

High tension line collisions – may kill up to 174 million birds per year. This figure extrapolates from European studies to the millions of miles of aerial wires in North America. There are very few data in North America.

Electrocutions kill tens of thousands of birds per year. This occurs mainly when large birds such as raptors make contact between a live electrical wire and a ground such as a pole. The relatively small number of birds affected belies the significance of this threat, since species such as Golden Eagle are more susceptible. Large predators like eagles have smaller population sizes and lower reproduction rates than songbirds, so removing a few thousand birds from the population will have a much larger impact than removing the same number of, say, Savannah Sparrows. Studies by HawkWatch International revealed an electrocution rate of just under 1 bird per 100 poles per year, or 547 birds at 74,000 poles in Utah in 2001-2002. About 10% of the birds killed were Golden Eagles, 34% Ravens, and another 25%Buteos (Red-tailed, Swainson’s and Ferruginous Hawks).

Cars may kill 60 million birds per year. Of over 8 million lane miles of roads in the US, 6.3 million, or over ¾, are in rural areas where most birds are presumably killed.

Wind turbines may kill 33,000 birds per year, and, as in the case of electrocutions, these birds tend to be large and scarce (e.g. raptors). The recent surge of interest in wind power has heightened concerns about their effect on birds, and has led to at least the discussion of efforts by the wind power industry to design more benign windmills and to choose locations that are less “birdy”.

Pesticides may kill 72 million birds per year or possibly many more. The sub lethal effects of pesticides may also make the birds more susceptible to predators or unable to reproduce, essentially killing them.

Domestic and Feral Cats – may kill 500 million birds per year or more. More information can be found at The American Bird Conservancy. Predators, of course, account for the vast majority of bird deaths each year, and most of this predation is natural. Domestic cats are not natural predators, but kill many birds. It is worth noting that house cats have been blamed for the extinction of two species of small mammals in the southeastern United States, and feral cats continue to be a huge problem where they have been introduced on many oceanic islands.

We should also note the progress made in wind turbine designs that significantly reduce the threat to birds:

Our hunch is that the Altamont Pass California wind turbines, reportedly the site of some of the highest bird mortalities associated with any US wind farm, and using what is now an antique turbine design, are at the root of the widespread association of bird mortality with wind turbines in general. Now might be a good time to have a glance at this site, to get some perspective on the hundreds of raptors killed per year by the Altamont turbines.

To help our understanding of turbine hazards to birds we'd like to make an analogy, to your bicycle. Turn your bike upside down or put it in a work rack, set it to the highest gear...the one you use to go fast on a level slope.... and now move the wheel slowly with your hand. The chain moves rapidly with only a few degrees of wheel rotation. This symbolizes today's cutting edge 1.5 mW turbines, which have a very large surface area of blade exposed to the wind and a gearbox that turns the dynamo quickly while the blades move slowly. Birds dodge these slow moving blades relatively easily.

Now put the bike in the lowest gear...the one you use to climb hills...and move the wheel with your hand fast enough to turn the chain as fast as before. That symbolizes the 20-year-old "bird-o-matic" wind turbine design. Small blades with small surface areas have to turn rapidly to overcome the magnetic force of the dynamos, which generate electricity.
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