What is the custom of ''feeding the wren'' or ''hunting the wren'' on December 26?

Where Im from in the west of Ireland its called Féile an Dreoilín..which translates as festival of the wren..and as far as i know it relates back to the story of the day all the birds gathered to see who could fly the highest and fastest..as the eagle soared high above all the other birds the wren hid in the tuft of feathers on top of his head..therefore being the bird that flew the fastest and highest...gaining the title "The Wren King"...and so people hunt the wren and go from door to door singing a song called "ó mo dreoilin" and collect money as a reward for capturing the wren king...its a custom that is dying out now, but was very popular in the 1940+...hope that helps!