Geese need emotional bonds, whether it's with other geese or other species. I started "goosing" 15 years ago when I rescued a goose who had been abandoned from the parking lot of a grocery store. He became deeply attached to me, and very lonely when I went to work or put him in the barn at night. The next spring, he actually fell in love with a white five-gallon bucket. (He was a white goose, about the same size). He had to sit by that bucket all the time, and made cooing sounds to it. This told me he was extremely happy and HAD to have a mate!
When I finally found Rosie, he went wild. I have never seen any being so full of joy. He has been a happy little goose ever since, and I have had them now all these years. We don't have ducks to be their friends, so I let them keep their first set of goslings (3 more geese thus added to the family). Every year, we sell or give away any babies, and the family remains the core group of 5. They graze on my lawn and take care of most of my mowing.
Ganders don't get mean when they have a mate, they merely get protective during breeding season. That isn't meanness, it's the survival instinct. They will bite if they perceive someone as a threat. To avoid that, don't do sudden, surprising movements when you're in their territory and don't walk in holding strange objects they're not used to without explaining and soothing them as you enter. Be especially careful in breeding season.
The more room the geese have, the less problems you will have, as nesting territory is often the issue. Respect their needs for space and their sensibilities, and you should do fine having two or more geese.
