B.L.
Hi P.
My son is 11, but when he was 3, I worked at a daycare and he went with me. I will never forget the first time (and thankfully the last) that my son actually bit another child there-when we asked him why he did it, he told us that he didn't know.
First, does he see this behavior from the other kids at the daycare? How is it handled?
You listed time outs, etc. which are all good ideas, but is that what you are doing or the daycare? What does the daycare do in these instances? Maybe they can sit him in timeout when they see him do it after he's been told to stop. Where I worked, they did that, and if the action was repeated after the child got out of timeout, the next timeout happened in the director's office. If it happened a third time, the child had to call their parents and tell them what they did.
Also, maybe try offering incentives since taking things away isn't working. Make a chart and make a point of asking the daycare workers if he pushed or pulled hair, etc. that day. If he didn't, then he gets a star on his chart. If he goes a certain amount of time without acting like that then reward him with something that he likes to do like going to a movie or bowling or playing at the park. Maybe earning something for good behavior may work better for your son than losing priviledges for innappropriate behavior. I hope I was able to help. Good luck, I know it's frustrating when you know that they know better!