I would be interested in seeing a scientific answer to this. We have a fairly large crowd of deer on our property, but they have limited range (about 750 acres, maybe). They also are limited in their diet, due to range, so I find it odd that the vast color range would be based on diet. I imagine that (just like humans) they may choose to eat one item or another even though several choices are available. That may explain it. Hopefully someone who knows for sure can enlighten us.