The HAWT are called fast runners. The reason they are called fast runners is the tip speed ratio (TSR) of this turbines are usually in between 5 and 8. This means the speed of the tip of the blade is 5 or 8 times faster than the wind speed. If a turbine operates at 10 mph wind speed, this means that the tip speed of the blade is in between 50 mph or 80 mph depending of the turbine design. While it may seam that the turbine is rotating slowly to the observer far ahead, it is different story for a bird flying nearby. The worst thing is that the flight path of the bird is usually 90 degrees to the turbine blade path. Thus while bird seams suicidal in the video shown below, the animal does not aware that something is coming with 50 or 80 mph speed from above just like guillotine. While they were evolving millions of years they never ever encountered a predator like this.
It is sad that the need of humans for energy increases proportionaly to the technological advancement. At the same time our population increases every second. We kill millions of animals by accidentally every year. Animals hit by cars, sea mammals and sharks are drowned in the fishing nets and ... Now we add another predator to the list called fast running HAWTs.
The solution to the problem? I do not know the answer to the problem that animals hit by cars or sea mammals or sharks drowned by fishing nets. But the answer for the killing the birds by the wind turbines could be VAWTs at the same scale and size of current HAWTs. These slow running VAWTs with their low TSR ("less than one") will never hit a bird so sneakily from the top like a guillotine.