I’ll bet they know each one by sight..when I was raising Angora Goats I could tell each one when out in the pasture. It got a lttle different when we hit 50, but it was with the kids that you’d have trouble recognizing...But then again I spent a lot of time with them....After our original flock of 18, hubby couldn’t tell them apart. He did the tractor, hay stuff and wasn’t with the animals as much as I was....He could tell the adult billy’s by their horns, but not the does......