Michael portillo did a piece on the wild man when he walked the pilgrim route through france and spain!!
I think
One of the frustrating things about the folklore of northern Spain is that it's very hard to find sources – at least in English form - that have not been influenced to the point of obfuscation by the overlaying of formal religion. I know this is not really an uncommon factor universally, but the effect seems particularly, and frustratingly, noticeable in this region. Paradoxically, it may even be a reflection of the power of those underlying myths – the Catholic authorities having, over the centuries, gone to extreme efforts (extreme even for them) to suppress the independent thought of this more Celtic than Mediterranean region, with its mists and forests and mountains, and - at night time - a true country darkness. (There is in Vitoria-Gasteiz the capital of Euskadi / the Basque Country, a bar called Cerveceria Rivendell. Not being a massive LOTR fan – I have to say that’s it’s one place that the name really seems somehow not in the least out of place.)
What makes it doubly frustrating is that I think that it's there - but just not as accessible as, in the era of the internet, we tend to believe all information is. Sources tend to be either somewhat bare in detail, or strangled by formal religion. I'm hoping there are books in Spanish and Basque which simply haven't made it to translation yet - and when I was living in Barcelona for a few months some time back I regularly checked the bookshops for anything that looked likely, with no real success.*
In popular culture, there are tantalizing clues in Dolores Redondo’s popular Baztan Trilogy of novels (the movie versions were available on Netflix last time I was subscribed). And a few years back there was the movie
Errementari - which was kind of okay, but nor really what I was looking for.
I can’t help feeling, that in a world with books on everything, we’re still waiting for a thorough examination of the folklore of northern Spain.
*On an aside, I'd recommend a visit to the bookshop Altaïr, on Gran Via (de les Corts Catalanes, to give it it's full if largely unused name), to anyone visiting Barcelona. Fabulous place. They also publish their own stuff.