Because it’s fanastisch!

wikipedia
informs me its English incarnation goes under a variety of titles:

The King and the Mockingbird
The King and the Bird
The Curious Adventures of Mr. Wonderbird
The King and Mr. Bird
Mr Bird to the Rescue
Adventures of Mr. Wonderful

Wikipedia also informs me that, as of 1983, no full English subtitles version was available on VHS (remember good old VHS?). Glad to see wikipedia is, as ever, keeping its articles up to date. Don’t know if there’s an English DVD yet but you are strongly strongly encouraged to hunt one down/ petition whoever necessary to release one/ learn French in order to appeciate the sheer majesty of this film.

It may just be the best thing I’ve ever watched.