Barred rock… one week old, aggressive?? Roo?

[sourland]

I would not consider the headspot on the chick in question as extra large.

And I'm not certain it is a barred rock.

 

[LaFleche]

And I'm not certain it is a barred rock.

This exactly.

I don't know which hatchery is providing Wilco with the chicks they sell, but if it is growing significantly bigger than the others of the same age it could very well be a Jersey Giant.