I've seen pictures of Altamont Pass wind farms. Lots of small, fast-turning propellers, as many as 7000 turbines running at any given time. Not very efficient. Newer turbines are much larger, about 300 feet tall, with huge slow-turning blades. Birds have no problem avoiding them. It's a matter of upgrading the equipment. Unfortunately it is the nature of most businesses to run their machines into the ground before buying anything new. Check out this photo of Altamont Pass, you can tell it's old technology because many of the towers are steel frame instead of modern tubular design. Altamont's turbines were built 20 years ago, long before the wind turbine efficiency revolutions of the early 1990's:

All those 7000 turbines generate only 625 megawatts. Now check out the highest tech available today, this is the Vestas V90: it has three blades of carbon fiber construction each 144 feet long, rising on a tubular steel tower between 300 to 500 feet all. A single V90 turbine generates 3.0 Megawatts of power. All those 7000 Altamont Pass propellers could be replaced by just 200 of these newer jumbo-sized (bird-safe) Towers of Power.