Rödhake, Erithacus rubecula, is ’robin’. I thought rödhake was simple to explain: röd is ‘red’ and haka is ‘chin’, but Hellquist thinks differently in Svensk etymologisk ordbok: haka ‘chin’ is closely related to hake ‘hook’ but there was another word hake, now only used in mässhake ‘chasuble’, from Old Swedish hakul ‘cloak’, with relatives in Old High German and Anglo-Saxon, of obscure origin but possibly originally meaning ‘animal skin’. Hekla, the Icelandic volcano is supposed to be a dervative of this.
Robin is short for Robin Redbreast, the personal name Robin being a diminutive of Robert.
The robin arrived here about a week ago, probably having spent the winter in Western Europe, showing off in a holly bush on an English Christmas card . In Sweden this role is occupied by a bullfinch on a Norway spruce.