gwynnie wrote: even more kamikaze birds [and]
Second point first. Anyone who balloons or skydives without knowing what's in that general area - be it high-voltage towers, windmills, whatever - is kind of asking for it. Balloons do drift, of course. I would say...as a general rule of thumb...if someone decides to plunge to the earth from way up...or do the Hindenburg thing...or pull a Mary Poppins and fly by umbrella...it's not really a windmill's fault if someone gets shmoonched by it.
If a silent windmill killed a skydiver...I think the family's lawsuit would get tossed. If I was a lawyer defending the windmill owner and the complaint was: it was too quiet? I'd argue...what should a windmill do...keep broadcasting a loud message: DON'T HIT THIS? Besides...there are way too many people.
Kamikaze birds... I don't know why they cause bird deaths, other than the obvious physics. I have no idea what the numbers are, but I doubt it's ever a big mound of birds at the base of those things. A few, maybe. I'd say it's probably the same issue as when birds hit buildings. They don't see
them. As strange as that may sound. Skyscraper...who could fail to see one? But...boomp! Another bird that will never fly again. We don't say: no more skyscrapers, 'cause they kill birds, do we. No.
Kamikaze...good term for it. Some of them must be.
I'm certainly no expert on either issue, birds or windmills. But I doubt that very quiet windmills would cause any more bird deaths. Because...probably the principal reason they fail to keep on flying is they don't see
the blade that hits them, or they hit. And...it may not necessarily be the case that sound up close is as many decibels as at a distance. I've never been near a big one, or studied the sound issue, so I don't know. But it seems to me possible that up close, the blades are actually quieter than at a distance. If so, making the blades quieter would presumably not
affect the bird strikes stats much.
I would guess that in terms of bird deaths, sound is not
the principal issue. It's visibility. That would certainly fit with birds hitting them, or getting hit, despite
they make noise.
Likewise, kamikaze deer bound out onto roads, like they are entirely care-free. Presumably their eyes are locked on the other side of the road, their destination, which - but for BANG! - they would reach. Cars make noise. So one would think...not now; car coming. But they don't see
it coming. I assume they are looking where they are bounding. I'm going over there
. A deer doesn't think: I may not make it. That would require a certain level of mental sophistication which they seem to lack.
Probably birds are similar. Doh-de-doh, I'm flying happily along - looking mostly where I'm going - I don't care what that 'whoosh whoosh' is - I've never heard a hawk or eagle that sounds like that, so what me worry - and then suddenly something is right in front of them, so fast they can't swerve, or it just - boof - knocks them out of the air. I don't think windmills should get the blame for it. Any more than a passenger airliner's engine swallowing a seagull should be blamed for the seagull's demise. Probably not too many seagulls make it all the way through the engine. At least...not intact. Do we blame the engine, or the airline, or the pilot? No. We blame the seagull. Stupid bird shouldn't have been there.
I'm sure it would be possible to rig the blades so they were more visible
to birds. Something like flashing lights on them. But there is no getting around the blades moving relatively fast, or the fact that birds will be birds.