You've done a great job Vinz! I need to learn how to define the area an action takes place (masking) in spatial parameters. Darktable, that I am using has a masking feature that I can define by value or RGB channel value and one that I can use a paintbrush. The paintbrush is not as easy as Photoshop or GIMP, it's more like a path function. Given that I need it very seldom, I haven't learned it. In this photo, unfortunately the background green is similar to part of the plumage... so I left some noise in, not to detract from the clarity of the plumage.
Obviously, you can mask better 
Thanks!