Barnacle goose were of the same nature as other birds. The question of the nature of barnacle geese also came up as a matter of Jewish dietary law in the Halakha, and Rabbeinu Tam (1100–71) determined that they were kosher (even if born of trees) and should be slaughtered following the normal prescriptions for birds. The mythical barnacle tree, believed in the Middle Ages to have barnacles that opened to reveal geese, may have a similar origin to the other legends already mentioned. Barnacle goose The barnacle goose ("Branta leucopsis") belongs to the genus "Branta" of black geese, which contains species with
Branta material and comparisms with other subfossil bones assigned to the genus "Branta" it was redescribed as "Branta rhuax" in 2013. It was another prehistoric Big Island form and remains known only from some parts of a single bird's skeleton, which were much damaged because the bird apparently died in a volcanic eruption, with the bones being found in an ash-filled depression under a lava flow. A presumed relation to the shelducks proposed by Lester Short in 1970 was generally considered highly unlikely due to that group's biogeography, but more recently, bones of a shelduck-like bird have been found on Kaua‘i.