Is one guinea pig a herd?

[Catherine]

I raised the five boys together at a time when I had a herd leader.  They all followed him and never challenged each other. It shouldn't have worked, but it did. 
They were always boys. They never really became boars. Boris is a big happy chubby piggie, but he would never accept another male. 
He seems content to live alone. We talk a lot and he can see me when I cook and do stuff in the kitchen. He is more bonded with me because he spent so little time with other guinea pigs.

Of course I made sure there was always plenty of food all the time.  There was also lots of room. I have an enclosure not a cage. If a piggie wants to take a walk he can. I have had a couple who wandered around a bit. The boys liked being together.