Does Bunny need a Buddy?

I have a male bunny that was found at a Costco Parking Lot late in the evening last year. I thought it was a baby but, after having him a year he hasn't grown.
   
He lives in a 9' x14'x 9'high aviary (food and water are covered) along with my 3 cockatiels and 1 parakeet. I put in a dog igloo for him to sleep but he prefers to be under it. (it's lifted on top of block bricks).
   
Is it beneficial for him to have a buddy? I'll have to get him neutered. How do you know if he's wanting to be with his own kind? What is the life expectancy of a rabbit?
   
Thanks