I think he means they don't sit still that long in a group like that because their nature is skiddish and solitary. I'm not actually sure of the solitary but I know they are pretty skiddish and fast.
lol..I am NOW really interested in what Orin meant by "Not usually this long a time."
I thought he meant they are usually not housed together this long of a time. He separates them as juveniles into smaller groups of one female and one male.