None of these versions seem to explain why the wren would be hunted down, rather than exaulted. I recall a vague story from my youth that had to do with the capture (and eventual martyrdom) of St. Stephen. All of the creatures of the forest were sworn to secrecy, and it was the wren that broke tryst and betrayed St. Stephen. I'm sure that I'm not remembering this clearly, but perhaps someone knows a similar story?

Lucius