My guineas are still young, and they are afraid of my chickens. I generally keep them in separate yards, but when the roosters got in the yard where the guineas were, they usually chase them.
Funny, I usually move the guineas back into their own little run before I let the geese into that yard to feed them. Yesterday I didn't take the guineas out first but fed them some scratch across the yard while the geese ate. The guneas finished first and ran full speed toward the geese (who are MUCH larger than the chickens!) as though they were going to try to ear with them. I'm glad they had the sense to stop short, since I imagine the geese would have nipped them.
But yes, my guineas right now are afraid of my chickens. Chickens are 5+ months old and guineas are probably still less than 3 months. I REALLY haveto set up that card file on the livestock I've been planning so I can keep tabs on breeding, medical care, ages, and all that