Cats do not get lonely like us: they are rather solitary animals who need socialization, not the opposite. (en.educhateur.com)
When researchers finally arrived, they found solitary animals, high up in the forest canopy, screened from the ground by dense vegetation, and seldom descending. (newscientist.com)
While dwarf hamsters of the same sex may get along, most hamsters are solitary animals so we recommend keeping only one hamster per cage. (pethouse.org)