This is an interesting and according to the people I've spoken to about the topic whose knowledge I respect; badly missunderstood.
The best free rangers are fast. The colour that is supposed to aid camouflage doesn't play much of a role. All the ariel predators I'm told hunt on movement.
Sitting hens is a good example, I used to wonder how a couple of the tribes hens managed to not get taken by hawks because of the exposed natare of the sites they chose to sit at. Donk, and her mother Dink, Fray, Tan, Thunder and of course Cheepy prefered exposed site. Their colours ranged from almost pure white to black and white and about every shade of brown. They survived by keeping perfectly still and when they moved from their nests they moved to cover very quickly.
Of course, this may not help much when it comes to ground predators who may locate the hen by smell. I am told that some hens more used to feral sitting choose strong smelling foliage to help hide in. Rosemary and Thyme bushes are favorite in many warm climates.
So, it's movement that usually gives the hens away. Donk, who is black and white and sticks out like a sore thumb once you know where she is is virually invisable while she is still. She looks like an odd looking rock.
Fayoumies (probably my favourite breed) are just too fast for hawks and the feral ones will fly into trees when in danger.
It's speed and stillness that counts most.