Because it sure ain't Schumann's. If you're familiar with with Wilco, I find the piano style and tempo to be uncannily reminiscent of Hummingbird:
I've just started work on a performance analysis of Fischer-Dieskau's 1976 recording of Ives' Ich Grolle Nicht setting, where DFD's phrasing borrows the structure of Schumann's setting rather than Ives' score. Mistakenly searching for Schubert and Ich Grolle Nicht, I discovered this gem.
My favorite moment of this performance? At 1:05, the mid-phrase terror that slips into the tenor's voice as he gets lost on a long tone during an inconvenient page-turn, and seems to be sight-reading.
I think it has all the makings of an undiscovered kitsch classic. Let's meme this to notoriety.