3 week old chicks fighting?

Hello all,

Total newbie with chickens here!
I have 4 three week old chicks (Light Sussex) hatched out by my broody Australorp cross. A couple of them have started to fight/flap around kicking up at each other every now and then - Momma chicken comes over and puts a stop to it.
Is this fighting between roosters, just sorting out the pecking order or something else?

Any advice would be gratefully accepted!!

 

Perhaps I should have added: -
I have 2 adult hens (Penelope and Nell) Penelope being the "top dog"
Nell hatched the chicks in the same coop as Penelope and they have continued to all live in harmony - Penelope showing some interest in the chicks and can occasionally be seen with one of the braver ones in tow looking for whatever she may scratch up out of the dirt. They are all given free range of the garden during the day and locked up safely within the coop at night.

Not sure if any of this is relevant!

Thanks again in advance for your input.

 

Oh thank you - that was my concern!
We would like to keep one of the girls - hoping that we have one!