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Comment by bz_bz_bz | Hacker News Reader

In terms of negative effects of wind farms on birds... reduced wind speed is truly the least of their concerns.

Wind farms do have meteorological impacts (e.g. onshore ones slightly dry the soil behind them). It is measurable but insignificant.

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Then again, in terms of direct threats to birds, ignoring climate change, things like powerlines (25 million birds a year in the US), and more significantly air pollution (200-2000 million), windows (2000 million) and cats (1000-4000 million) even very high estimates of 2 million a year including things like habitat destruction and extra powerlines (more direct estimates from collisions are around the 500k mark) from wind turbines make them in turn seem like the lesser of the problems.

Which is not to say it's not an important factor, especially as they affect very specific kind of birds disproportionately, but it's not like wind turbines are primarily bird-killing devices, and it's even possible they may be net benefits to birdkind by, say, reducing air pollution.

There was a study a few years back that saw radical reduction in bird strikes simply by painting a single blade a contrasting color.

I believe bird strikes went down when they made the windmills much bigger, and the angular velocity of the blades much lower. Not building them on open truss towers encouraging birds building nests under them also helped.

If you’re interested, here is some info about the study I mentioned:

https://group.vattenfall.com/press-and-media/newsroom/2022/b...

https://climate.mit.edu/ask-mit/do-wind-turbines-kill-birds

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