Everytime another compy comes near another, they get a boost. You can see the "+1, +3" etc etc. If you tame a bunch of these and put them in your house they're good for distracting players if you also have dimorphodons or onyc inside too
Breeding a high level compy army is a waste of your time so taming a metric f*ck ton is the way to go. Riding a slower animal while surrounded by your army feels pretty awesome and it's hilarious to whistle attack target on whatever irritates you.