Very nice work there, it looks like you have done well with the exposures - 4 is very well exposed. However looking at the Corella you can see that the white of the bird has lost the detail in the feathers = a tricky subject being all white. One thing I have had advised to me and I have found to work well (especially when combined with RAW shooting) is to underexpose when dealing with whites and bright light (and to underexpose when in the brigher parts of the day)usually by about -1 which will then help you preserve the whites. From there in editing you can go on to brighten the shot (or in RAW boost the exposure) to restor the brighness to the shot - and as you underexposed before there will be the details in the whites to show, whilst with normal or over exposing the whites lose the details.
Of the set I would say the last is the best because you have managed to preserve the details in the whites and not overexpose and you have a good close up with eye contact. It also (to me) does not feel too constricted either as the direction of focus is the lens - thus the viewer so the eye is not left looking for the space that the animals eye is following
After that I am very impressed with the bar removal you have done and I would be very interested to have a look at the original versions of the shots (if you still have them) to see what they looked like before and to have the details of how you removed the bars - something I have not mastered at all.
ps the first is a Lady Amherst (male)