I'm glad you posted this. Hopefully now we who care about clean energy don't have to fight with those of us who also care about biodiversity and species health, because we are the same person! For too long this avain mortality issue has been used as a red herring against installing wind power. Let's make an agreement that if we conduct resposible wind siting studies to minimize avian impacts it should not be a big issue for us to argue about.
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Amen.

And let's also take the time to respond with 'letters to the editor' on articles that propagate, further, this lack of perspective. Only with direct feedback can we help these "reporters" figure out the meaning of the word "investigative" which at one time characterized their work.

I read statistics that over 10 years a windfarm in the middle of the Mississippi flyway killed 1/10 the birds killed by the Exxon Valdez alone. So, every year a windfarm will kill 1/100 the number of birds killed by one big oil spill? Not bad.

For several years I worked on the 48th floor of a Chicago office building. Every year I knew when the monarch butterfly migration was going on. I'd see them go by my window. I wonder how many butterflies are killed by buildings too? I see lots of dead small birds during migration season but not butterflies.

Maybe if the windmills were taller they'd miss more birds - above 40 floors, all I saw were falcons, butterflies, and spiders.

I noticed a mention of cats as a major cause of bird mortality. I wonder how true that is. It may, in fact be a cause of small bird mortality, but not large.

Here in Tokyo, where I live, we have major crow infestations. It gets worse every year.Despite the fact my wife feeds a dozen alley cats, we have more crows now than ever.

Small birds, such as sparrows have disappeared. I have personally seen them attacked and eaten by crows. Cats seem to completely ignore birds here in Tokyo, as there is a large amount of other small game for them to hunt, such as field mice.

Bird lovers will immediately know what I am talking about : all of our "crows" are actually Corvus Asiaticus, which is a large raven.

A lot more work is needed before one can conclusively point to cats as a major cause of bird mortality. Other types of birds , crows in particular, seem to be much more involved in predetation than cats.
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Ravens and crows both eat bird eggs and young, rfrom nests. That is why you will often see small birds chasing a lone crow, diving and screaming at it. Sometimes the predation is severe on colonial breeding populations, especially waterfowl.

Feral cats in a rural setting hunt for all their food. Domestic cats in a urban setting, let to run for part or all of a day will do the same when the opportunity presents itself. Predators predate. It is their nature. The only cat which never kills a bird is a cat kept indoors.

ok the quote says between 100 million and 1 billion. THATS A DIFFERENCE OF 900 MILLION!!! I don't mean to bash but 900 million is a big number and if the guy can't figure out a closer figure then that then he probably shouldn't be trusted... at all

"Ravens and crows both eat bird eggs and young, from nests. That is why you will often see small birds chasing a lone crow, diving and screaming at it. Sometimes the predation is severe on colonial breeding populations, especially waterfowl. "

In over 25 years of watching closely both birds and cats in Tokyo, I have few doubts that cat predetation has little to do with the demise of small birds in Tokyo.

One rarely sees crows alone; Corvus Asiaticus is particularly gregarious. Crows are so know for their flocking propensities that there is even a word for a flock of crows in English: a "murder" of crows.

I have yet to see defensive tactics by small birds, such as is described. The Asiatic Raven is a big bird--bigger than many cats--specemines in my vicintity often run over 1.5 kilos with wingspans of 80 cm.

It is a highly efficient predator, and as such is probably the true villain, not cats for the demise of small birds.

I also note that as many of the birds in the Tokyo vicintity are much larger than cats (ducks, cranes, egrets) cats leave them strictly alone.

"Feral cats in a rural setting hunt for all their food. Domestic cats in a urban setting, let to run for part or all of a day will do the same when the opportunity presents itself. Predators predate. It is their nature. The only cat which never kills a bird is a cat kept indoors."

So will predatory birds, which are in a much better position to prey on smaller birds than cats are. Crows are omnivors and accept meat gladly. Japan is also home to many types of hawks, a type of bird which quickly adapts to urban environments. A well known suburb of Tokyo, Mitaka literally means "Three Hawks"

Large birds are not at danger from cats ; small birds are not solely the victims of feline predatation; avain predatation is also a major factor.

Perhaps the best way to keep a bird safe from any type of predators is to keep it safely locked indoors.

Dear Mike and others interested in accuracy of the bird kill estimate(s) cited. You may be wondering why not a single projection? The ornithologist has very reasonably...as we should demand of a serious scientist...put upper and lower boundaries out for us to consider because he realizes that estimates are of low precision. Counting dead birds is hard enough, given the size of the earth and rapid growth of cities. Extrapolation of rates from sample counts is based on assumptions about land use, building height averages, wind patterns, window reflectivity, native versus migratory bird demographics and migratory patterns, and so on. Perhaps it would be better to have said, for a lay audience, "at least" 10M or "up to" 10B to get his point across. Regardless, it is because of his openness about low precision that we should take him seriously.

There was an article on this in a recent issue of Environmental Building News, which is probably the best respected trade publication in the green building industry. So it is getting some attention, though probably not all it deserves.

As for the building mortality vs. windmill mortality issue: I wonder what the proportions are of small/prey birds vs. large/predatory birds in each case. As far as I know, raptors don't often hit buildlings, but they are often killed by windmills. Does anyone have any more definitive information on this issue?
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Some of the earliest wind farms were sited without adequate thought and public input. Altamount CA is the best example, as it is/was a major migration corridor or breeding area. About as smart as putting a windfarm at the peak of Eagle Mountain in PA (which has not happened but could if money over-rode common sense). The data are avaialble to keep wind farms away from major migration routes and key breeding habitats for raptors. We just need to use them.

Keep in mind that the mortality data from last year's technology do not well represent the potential from next year's. The radii of the turbine blades has so greatly increased that the revolutions per minute have lowered significantly. Extrapolations from past data are only valid if re-calibrated accordingly.

I guess I wouldn't lose much sleep over any so-called "window-crash bird mortality" figures; what if the houses with the large panes of glass weren't there? There would probably be a larger population of predators snatching up birds, which would likely have a similar impact on the bird numbers. And what if the occupants of those houses weren't putting out feed for those birds? The bird population would probably be lower.



The net effect of having people and small birds cohabitating an area is likely beneficial for the bird population. As long as bird populations remain constant or increase, there is little to be concerned with. Hand wringing over what a few would label as alarming statistics isn't worth the trouble.



John said, "it is because of his openness about low precision that we should take him seriously." Excuse me? It's such "openness" that make many of us question the science behind much of what is published these days. It seems that everyone has an agenda and bends the data to gain attention when it is undeserved.
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You only looked at half the equation with your analysis. Population equals recruitment minus mortality, averaged over the period of time roughly equal to the age of reproductive maturity. Usually a negative P over time happens from multiple factors: not just predataion for example. But put elevated window crashing on top of severe habitat loss (development) and predation (cats) and extirpation is a possibility if range is limited... or not. Passenger pigeons for example.

NPR story on bird-safe windows.
http://www.npr.org/templates/story/story.php?storyId=5076012

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Thank you for the reference link. It's a terrific article with case study of prototype preventive measures..

Wouldn't it be interesting if bird retinal sensitivities to the the electomagnetic spectrum were slightly skewed from the human, and a window coating could be made that was visible mainly to flying dinosaurs. Even better if it had some energy benefit!

We're just east of Seattle a 100 miles, urban growth has swamped us, all of the farms are going for housing, I'm supporting and annoying the NIMBYs by supporting windfarms proposed here as they'll tie up farm land for 20 to 25 years w/o houses on it. Our local land owners have gotten dollar signs in their eyes as developers are making it very nice to sell out. I wish windfarms were loud, dangerous and polluting like coal and natural gas, but they're not, as that would scare people, they're quiet, annoyingly individual, sigh, someones going to figure out how to put condos in a windfarm and it'll all be lost. No more open spaces...