I have 2, 1 week old Aylesbury ducklings and 3 1 day old the same. Obviously there is quite a big size difference but I was wondering if they could share the brooder or should I setup a separate one?
You may have to intervene since you have such young ones, you could always divide the brooder and let them all get to know each other better before putting the tiny ones in with the larger. Divide so they can all still see each other but the older can't pick on such tiny ones.