Mountain chickadee

I know Mt chicks have a striped cap, as opposed to the solid black cap of their Eastern relative, but I was surprised to see such a pronounced white eyebrow. So I looked it up to see if this is a sign of age, like our graying at the temples. Turns out it is quite the opposite! The white stripe fills in with dark feathers as the birds age. So this is a newly minted adult Rocky Mountain Chickadee!