https://www.popularwoodworking.com/projects/the-way-wood-works-birch/

I found this, which might help you: Red Birch

Thank you. I’ve seen both of these in my research, but they don’t show me how red birch ages. I’m hoping someone here has a real life example. I’m looking for examples like this, but for red birch. https://www.woodmagazine.com/woodworking-tips/techniques/finishing/color-changing

Did you see this on Houzz? Houzz Question on Red Birch

This flooring web site says red birch darkens, but not like cherry does. Red Birch Flooring It does not offer any pictures for comparison.

Thank you. Yes. I’ve seen those, but they don’t show an example of natural red birch new and aged like I’m hoping to find. I was hoping someone has natural red birch in their home and can provide a side by side photo new and after time.

From Scherr's
https://www.scherrs.com/contents/en-us/d53_ColorShift.html

'Red' Birch is heartwood, 'Yellow' Birch is sapwood.