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 thessaliensis Mammal Neogene stage MN12, 7.5-6.8 million years ago) deposit at Perivolaki in Thessaly, after which region the species was named. Both near-shore freshwater bodies and open grassland habitat were found in the Perivolaki area during MN12. The species provides further support for the distinctness of "Branta" from the "Anser" grey geese by that time. It also suggests that the present biogeography of Eurasian "Branta" - breeding at Arctic and wintering at Mediterranean latitudes - is a product of post-Miocene times, possibly due to range shifts during the ice age era. In this aspect it is notable that such a breeding-wintering