The blacks look very good, but the yellows, on the crown and upper back have lost almost all their detail. I first thought they were blown, but a quick check in NX2 shows that they are not. Did you do any post processing in this area that would have pulled them back from the right edge of the histogram? In that case, they no longer register as blown, but you can't get the detail back if it was originally lost.
In a perfect world, I wish t the leaves didn't overlap the bird below.
Nice pose from the bird, I've always liked it when we can see the primaries of the folded wings cross each other. Too bad the FG leaves touch the goldfinch, and there is PP evidence near the head and neck. Some yellows are a bit bright especially on the back...I'd suggest selectively desaturating them a few points - you may find some hidden details in there ;-)
Sorry for some of the repetition...Randy was quicker typing his reply than me :-)
I assume not much crop since you did not use all the 400MM focal length. The shutter speed was plenty fast @ 1/800, did you run noise reduction on the bird too. Some applications smooth out the detail and make the subject look flat, others like Topaz do not. Regardless, I am sure you know noise reduction software needs to be config correctly too. If only the camera was a tad bit higher or left. I like the composition and habitat type environment.