with guinea pigs is it true that the larger the herd the easier it is to...

[Melorious]

...introduce a new piggie? this tends to be true with females,

 

[white rabbit]

Guinea pigs are natually very social animals and I've read that they live much longer if they have at least one other one to live with. My mother would only have one at a time and they never lived long, no matter how well she cared for them, whereas people who have two or more tend to have happier guinea pigs that live longer. I don't think it necessarily matters how many guinea pigs there are when you introduce a new one, because they're social animals and tend to like each other. But I suppose the more there are, the more they can socialize.