Amazing that others do not have Guineas that ruin plants, while they do not scratch like chickens, they tear off branches of my young trees, and peck at the stalks of new trees, creating deep punctures that are oozing. Also they try to make nests where my shrubs are and cause the shrubs to die off. They all got along with my chickens the first year and half, and there appeared some aggression around the time they started laying big 'ol nests of eggs. I am not sure what they actually do to the chickens, but after the attack, the first one died off and now the other one is looking like it might recover, but both were weak and not doing well. I do not see any wounds. A while back, when I caught up my guineas to cut their wings so they would not fly over the fence, they scratched me up pretty good flying up trying to get away from me, their nails on their claws are pretty sharp, so I can only imagine what harm they would inflict when purposely picking on another, like my chickens or dogs.