I think they really do need to be kept in pairs like rats do. I started with one bunny and had to wait about a month before I could get the next one from the breeder (had to wait for the second litter to be weaned). It was AMAZING the difference in overall behavior of the first bunny after we got the second--it was SO obvious she was happier and her overall quality of living was much improved. Even though we gave her lots of love and attention every day, our human companionship was no replacement for bunny love.