 The aptly named "Anser atavus" (meaning "progenitor goose") from some 12 million years ago had even more plesiomorphies in common with swans.In addition, some goose-like birds are known from subfossil remains found on the Hawaiian Islands.Geese are monogamous, living in permanent pairs throughout the year; however, unlike most other permanently monogamous animals, they are territorial only during the short nesting season.