While it's usually best to keep at least two birds, every bird is different. Canaries are solitary birds and usually prefer to be alone (especially the males). My cockatiel is an "only bird." I actually would like to have two birds, but my Buzzy is a rescue who had previously been kept in an overcrowded cage, and the other birds bullied him and pulled his feathers out. His neck is still bald, over two years after his rescue. Because of that, he does not like being around other birds. At all. He seems to prefer being around people, and he seems to enjoy having an entire cage (an entire room, really) all to himself. I spend about 4 hours with him every day on average (sometimes a little more, sometimes a little less), so he does get plenty of social interaction.