Thank you so much! Osteo Form-SA is the calcium powder he left with me. It's typically for much larger animals so I'm to give him the tiniest pinch once daily.
As for his diet, believe it or not, Willow is the PICKIEST squirrel I've ever worked with (in his case, lived with). I think part of his good health stems from never having been caged in his life. He lives free in the house and I do believe that makes a difference. It wasn't easy for the first few years, but living alone, I managed, and he eventually calmed down and learned to be a house baby. That being said, I totally understand why that is not feasible for most squirrel parents to do. I totally get it and it can even be dangerous when they're young and mischievous.
As for food, his base diet is 2 Henry's Picky Blocks for breakfast with a leaf of Roman hearts - I've tried other greens but he just refuses to touch them, which is so frustrating. Aside from breakfast, he eats a seasonal variety of foods ranging from watermelon to pumpkin, cherries to snap peas, maple twigs to rose hips. He can be weird about grocery store produce (which makes me wonder what we're all eating), but when possible, we forage locally in safe, pesticide-free areas and also organic farmer's markets. He does eat an organic dried cranberry nearly every day - that's his candy after dinner. About 2 - 3 times per week he gets a hunk of organic avocado, meat only (no skin or pit). I do include a multivitamin hamster drop in his water. His water is always filtered water. A few times each month he gets to lick the tip of a spoon with a small amount of coconut oil. I make him flax meal pumpkin cookies and he eats a few of those per week. A dab of plain Greek yogurt a few times per week. A segment of cuties tangerine now and then. Oh, seeds! He gets a variety of seeds, but they are not the majority of his diet (maybe 1/8th of his diet) and seeds and nuts are always dusted with calcium. Nuts are mostly almonds with a treat of walnut or pecan, or chestnut now and then. He does get 5 fresh kabocha squash seeds daily (I deseed kabocha and freeze the seeds with a bit of the flesh on them then pull a few out each night for his breakfast. During spring and summer, he will eat a rose, magnolia, or camelia flower when we have access to them. He chews on elk antlers that I buy from reputable outlets. Pretty much, he eats a large variety but he decides for himself. I put out many items and he picks and chooses and goes through phases. He has been known to steal a Dorito or Nutter Butter from time to time