Is this normal chick behavior?

I have 11 new babies that I just got on Tuesday, they were hatched on Mon. In the group are Speckled Sussex, Silkies, and possibly, a RIR, White Rock, BO,EE, Barred Rock and Australorp (some of the breeds were from "assorted" group) Anyway, this is only my second time brooding chicks. My first batch was in March, and I had 8 then, with one duckling. In that group were mostly EE and 2 Blue Andalusians. This newest group seems much more friendly, and curious, as babies. With my other group, if I were to tap my finger on the ground, or in the feed, like a mama hen would, one or two would come running up to check it out. I always thought this was so cute. So I tried it with this new group. OMG! They act like a piranha going in for the kill! All but one or two attack my finger if I run it along their food tray! I mean crazy like! Not just, oh what is that?, more like "FINGER, MUST KILL FINGER!!!!!" And watch out if I actually peck and kick some of the food around in the tray! Is this normal? It seems to be a few of the Silkies and the Speckled Sussex that do it the most, but the little black ones (not sure what they are yet, possibly Australorp or JG), and the little yellow ones, (not sure what they are yet either, maybe BO, or WR), do it too. The only ones that don't seem as interested are a few of the other Silkies and the RIR. I have ground their food up, since I knew the Silkies would be small, and I have seen all eat at one time or another, so I don't think it is that they are starving. One of the SS that does it, even flares her wings sometimes when she goes after my finger. FYI, they also go after the food on the ground too, they are just going after my finger. Any ideas?
Thanks!

 

Good to know that it is all crazy food antics. I just thought it was weird that one of the SS even flared her feathers when going after my finger. Geesh, guess I'll have to be even more careful as they get older! I may come away from the feeder with battle wounds!