Thanks for the comments and suggestions
Using a sony's ar7 iva ( based on the suggestions of all here when my d800 died, I bought the best lens I could afford sony 200-600 and then an affordable compatible mirrorless. Am pretty happy with going that route)
I believe that I used the crop setting on the camera so it should be about 24MP or so. I always shoot raw and have recently been playing with auto iso and manual but will go back to full manual since I seem to lose track of my iso and they have been running too high.
I had noticed much better pictures when I tend to a lower iso. But I do hand held and have to be careful of blur so use a fast shutter. Sometimes exposure is a problem depending on lighting etc.

Shooting in off angle harsh light (as you did here) is always going to be a challenge compared to morning or evening with softer light. I am a manual exposure guy myself, although many here will argue the affectiveness of various forms of auto exposure. Here, you are at a constant lighting condition, so you should be able to hone in your proper exposure. Here, the secret is going to be not to let those highlights get away from you. There are going to be several options that will allow you to do that, but with Sony gear, the use of Zebras is a great tool. If you are interested in learning about how to set them up with your Sony camera, use Youtube and search for "Sony" and "zebras" and it should take you to various sources such as Mark Smith and Mark Gailer.

Regarding your photoshop techniques and the difficulty associated with these types of images, I'll guarantee you, if you. have the right light as well as good sun angle, your post processing will be a hole lot easier. Good luck!

Iso was about 250 to 500, lens was 350 to 600, f = 1/13, speed = 1/1250 flexible spot metering,
It was the end of day, light was low and very contrasty, bird was very white, really wanted to get feather details, leaves were very dark orange

How do you approach setting exposure in the field and then how do you treat with photoshop.
I use the adobe bridge and change exposure, contrast, highlights, shadows, black, white, clarity and curve bars
I can use curves and levels and exposures and gradients in photoshop but prefer to do most everything on raw file in bridge. I don't like masking because my borders always look bad. As you can see here when I tone down the orange leaves i end up toning down birds bill. I could select the bill and saturate it more or less but again its really hard to accurately border it without making it look unnatural (at least in my hands) thanks for your comments. This is a brand new camera for me so I am learning how to hold it and focus properly and use back button focus and iso auto. I usually preferred manual with setting my iso manually and so far have not had too much luck with manual with auto iso since I then end up paying less attention to all my settings! Maybe it just takes time.

Thanks for your comment. I may need to learn how to use a flash to balance the light. I didnt think it would be effective at big distances but I have to admit I have NO experience in the benefits and limitations of flash. Often with birds, the sun is FREQUENTLY in the wrong place. Now if I could only control the birds or the sun I'd be okay! but often my location is restricted by what's allowed or not in the areas I am shooting. That's what makes shooting birds challenging and fun at the same time.