The Myth That Wind Farms Are a Guillotine for Birds Is Being Debunked by Hard Data
(www.zmescience.com)
Birds can see more colors than us, at least the majority of them, we have 3 types of photoreceptor: red, green and blue, but they also have a 4th one that allow to see ultraviolet light; that means that bird see a wider range of colors than humans so i strongly doubt that they can't distinguish between light grey and white