Overpreening?

My guess "moult", combined with the interesting property of most derived birds of not having complete feather coverage in their skin; it looks like it from the outside, but the actual feathers are all in defined lines. (Defined lines with no phylogenetic signal, alas.)
Of course, it could be a nervous disorder from being stuck in a cage with mousebirds, or just a really really truculent itch, but having watched the hoopoe in question preen like a mad thing having a good time, I think 'moult' is the correct explanation.