Bird from the Book of Kells. This looks like it could be a goose. The wild goose was the Celtic Christian symbol for the Holy Spirit. One could take this pose, put a peacock crest on it, and make the tail feathers long peacock feathers for a pretty image.
Chi-Rho from The Book of Kells, an illuminated manuscript Gospel book in Latin, containing the four Gospels of the New Testament, together with various prefatory texts and tables. It was created by Celtic monks ca.
The Book of Kells – Day One of Medieval Manuscripts