What a sweet photo!
Thanks for caring so much about your squirrels!
I give my wild squirrels a variety of unsalted nuts (some in shells, some not). Usually walnuts, pecans, hazelnuts, and almonds. Slices of ripe avocado (no seed or pit) - it's a great source of healthy fat and most squirrels love it. I also try to get them to eat vegetables like cauliflower, broccoli, green cabbage, etc. I occasionally buy a package of cubed sweet potato and butternut squash and they seem to like that. They also get fresh coconut chunks, some apple, a mandarin slice, and a few other pieces of fruit from time to time. I limit the amount of fruit they get due to the high sugar content. They like variety, so I do my best to change it up as often as I can & they always have plenty of fresh water.
I've also made homemade squirrel block for them (based on a recipe I found here on TSB). That wasn't a big hit, so I made Boo Balls and added quite a bit of almond butter. That went over better, but it's still hit or miss. Here are some recipes if you're interested:
https://thesquirrelboard.com/forums/...dly-Cook-Book) and this:
http://cliptomize.com/Clipbook/View/...ret=jf7yk2rk8p
In my experience, younger squirrels are more willing to try new foods. My wild mama squirrel has a new litter of babies (there are four or five of them and they're about ten weeks old), and I'm not giving them any nuts yet. I'm doing what I can to introduce them to healthy foods before they have a chance to become nut junkies. At least the babies seem to like the squirrel block I made!
I sometimes dust the nuts (and other food) with calcium carbonate powder to provide a bit of extra calcium (nuts are high in phosphorus). Wild squirrels can eat more nuts than those in captivity because they know how to balance their diets and are not solely dependent on humans for food. Like you, I use this as my guide:
https://thesquirrelboard.com/forums/...-Pet-Squirrels, but I'm more generous with the nuts and a few other items as they're wild squirrels.