Translation:Do you notice? That squirrel is already gray.
"Do you notice" just isn't used this way in English, so any translation will have problems.
"Did you see" would be the best fit in most (but not all) scenarios. However, we would then incorrectly assume that finnish also expresses this in past tense.
"Can you see" is a good suggested translation and they should except any reasonable variant.
Perhaps this is a reflection of my language region (although the inappropriate downvotes suggest others agree), but "Do you notice?" or "D'ya notice?" can't be used as stand alone sentences or interjections as "Huomaatteko?" is here. To my ears it sits calmly nestled at the front of a sentence, never excitedly in its own. Hence my suggestion of "Did you see?". Again, no translation will be perfect.
Osaatteko näyttä also (are you able to see) voida is more are you allowed / permitted.
Either way its stretching the the verb huomata to claim its can you see
How many different variations of a translation of "to notice" does DL beleive there to be