Lovely to see, especially the Greenfinch, not many of them about.
A couple of things, if I may, as you've asked for critique.
Feeders are great for drawing birds in but not the best subject for a perch, being man made and they aslo tend to dominate the image and become the subject. Put a natural perch, a branch or similar next to the feeder, photograph the birds when they perch on it, before they jump to the feeder. You may only get a second, so be ready. Pre focusing on the perch will save you time, AF should pick up the bird far quicker when it lands that way. Experiment with perches and backgrounds, although you already seem to have a nice background.
I think you've oversharpened these considerably, the first Blue Tit is only a touch over sharpened and has some sharpening halos around it. Dialling the sharpening back a bit would look better I think and would make the better image of the 3. The second Blue Tit is slightly more over sharpened, it's actually noticeable on the feeder, as well as the bird. The bird just has a little too much texture, as well as a sharpening halo, particularly around the tail.
The Greenfinch, again, just a bit too heavy with the sharpening slider and is the most noticeably oversharpened of all 3, with significant haloing.
Please don't take this as a negative, it's not meant to be, sharpening can be a fine line between just right and just too much.
Colours, exposure etc all seem good to me.