I thought her throat was cut. I have had to separate the ducks from the chickens to maintain peace. He is not agressive towards any of the other birds nor to me.
Ducks can be very aggressive, particularly if they perceive a threat.
I would also guess that the California pullets are more active and maybe aggressive acting than the other breeds you have, which could possibly explain why he goes after them. I would say separating them was the best solution all the way around. Our khaki drake goes and climbs on our white chinese goose when she is trying to lay. He shares 7 females with a crested rouen drake and still all 7 females have no feathers on their necks because of him. He does chase the male goose away from his girls though, so Colleen could have a good point.