They won't kill the same kind of birds, though. For example, there's a new rule raising the number of bald eagles which can be killed by wind turbines to 4,200 per year. I'm guessing that house cats kill few bald eagles.

It may still be a nonissue, of course, but the comparison with cats doesn't tell the whole story.

Fair point, I was just responding to the idea that wind turbines would kill all the birds, which isn't realistic. As a percentage of the bird population, it's negligible.

I don't see any reason why bald eagles would be more likely to be killed by turbines than other species of birds. If only 0.01% of birds are killed by turbines, then they would only kill 1 bald eagle a year out of thousands.

Regardless, this is more of a reason to invent solutions for repelling birds from turbines. Maybe we could come up with noises or lights that repel them. Or drones, or a water cannon robot. But I'm not certain it's even an issue.

The current rule is something like 1,200/year. There are about 143,000 bald eagles in the US. The 4,200 number is set at a level which they think the species can sustain. I don't know why bald eagles would be more likely to be killed by turbines, but apparently they are:

http://www.fws.gov/midwest/wind/wildlifeimpacts/index.html

"Not all bird species are equally vulnerable to wind turbines. Eagles appear to be particularly susceptible."

Not all birds fly the same way, in the same regions, at the same altitudes. Balds eagles tend to soar and hunt in places we like to put wind turbines. Small birds tend to move smaller distances, often in about 100m around a water source.

Thanks.

Wind turbines kill <this type of bird> is highly location specific; so again, saying wind turbines kill lots of bald eagles is also not telling the whole story.

And eagles may kill smaller birds, so the net might be positive? More sub-optimization.

...Eagles aren't generally bird hunters. Bald eagles for instance, eat mostly fish.

It's a nice thought though, just kill off the big birds, and watch the benefits "trickle down" to the little birds. /s

You're going to have to provide documentation of this.

Of what? The new rule allowing for 4,200 to be killed each year is a simple Google away. The conjecture that house cats don't kill many eagles is just common sense, and if that's what you're referring to then I assume you're just making a joke.

House cats should be just that, house cats. Their environmental impact is detrimental. Plus, all of the neighbor cats shit in my raised bed gardens and piss me off.

http://www.bbc.com/news/science-environment-21236690

It's not so bad. We've killed most the native predators, so cats are the only thing keeping populations under control. And like most predators, they generally target sick and weak prey. And the cats are just trying to help fertilize your garden!

> And the cats are just trying to help fertilize your garden!

Yes, that wonderful, fertile cat shit full of Toxoplasma and other parasites. What a great addition to my garden! Not to mention that wonderful feeling and smell when your sink your hands into cat shit while prepping a garden bed.

Your other point, in regards to keeping populations under control, is way off the mark. http://www.nature.com/ncomms/journal/v4/n1/full/ncomms2380.h...

Keep your cats indoors, people! They're great pals to have, but inside.

That study doesn't necessarily contradict anything I said. I agree that cats are now the largest predator species of birds, but we've killed most the other predators. It also credits unowned cats as doing more than half of the predation, so keeping owned cats indoors wouldn't fix it.

Per capita, or overall?

Overall.

As of 2012, the estimate is something like 225 thousand wind turbines around the world. The best estimates I could find for domestic cat populations is between 200-600 MILLION.

I have no idea why per capita estimates are relevant at all in this context. Wind turbines are vastly larger than cats and serve an entirely different purpose.

The point is birds are not going to go extinct even if we increase the number of turbines ten fold. It wouldn't even make a dent in the bird death rate, which cats are only a small part of.

Hm. Birds multiply by X every year in the spring. Yet each fall we have about the same number of birds as last year. Brutal fact: the fate of almost all birds is to be eaten. If not by cats, then other creatures that live in the cat niche too. Remember domestic cats are a tiny fraction of the world population.

Which world population?

Domestic cats surely dominate all other cats in population.

I didn't realize that to be concerned about something, their extinction had to be on the line. Then again if that is your standard, I can see why you keep talking about birds, instead of bats.

If it's not extinction, what's the issue? We accept that millions of birds die every year. They have to or the population would explode. Everything from cell towers to glass windows kills ridiculous amounts of birds, and no one cares. Why are wind turbines, which don't even make a dent in that, somehow special?

I don't see why the numbers would be significantly different on bat death rates than bird death rates.