Maybe not enough room? I had one duckling that was mean to everyone else for a while and then chilled out. She was smaller too so I think she was making up for her size by being mean so she didn't get picked on.
At 4 weeks I'd hang a romaine head in their brooder it will keep them busy for a while. Mine loved to nibble on it and it keeps them occupied also if you can which if you have snow you may not be able to but digging up some turf with the dirt attached [free of any kind of spray] and put in the brooder they will make mince meat out of it but it is so good especially for the chicks to help build up their immunity for when they go outside.Be sure to put out some grit when feeding anything besides their starter.
That's pretty typical, if you have blue kote you can easily cover that so they aren't drawn to it. Seems once one gets started they just keep it up. Lettuce won't hurt them at all. or chick blocks TSC has themThis is what it did to one of our Rouens :-(
TSC carries it and it's very safe to use anywhere except eye or mouth. it has gentian violet in it so it covers by making the wound or what ever your trying to disguise purple. cheap too. I finally found it with a dauber inside instead of the spray. you have to be very careful when using it because anything it touches will be purple for a long time or forever if you look at some of my clothes and towels. But it is wonderful for wounds for disguising wounds too. and for discouraging pecking because it totally throws off the duckling who has been pecking. works great for chickens too.
