Masking problem

[Doc_Pit]

I usually figure out how to mask pretty much anything, but here I've hit a wall. 

Generally, I start with a B&W adjustment layer, using the various sliders, and combine that with other adjustments to get as close as I can to a white subject against a black background.  Couldn't find any combination of options that showed any promise.  Traditional tools like the magic wand, quick selection or color range are no match for the fine network of feathers against a background that, in places, is not very different in color or tone from the feathers themselves.  Is this just a "punt" situation?  Or is there a way to approach this?

[c.pfaffenbichler · Accepted solution]

The background being so similar in hue and luminance in various regions I am afraid extensive painting may be hard to avoid.