black squirrel in the 'hood

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I've seen black squirrels in Ann Arbor a few times in the past.  Once last year, there was one in our back yard.  Today I saw one across the street.  It was small, for a fox squirrel, but I don't think we have gray squirrels around here.  And sometimes fox squirrels are as small as the black one I saw.

I wonder what the color genetics are in squirrels.  I wonder if black is dominant or recessive, or if it's not that simple......

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