On our walk around we saw a couple squirrels. I got some movies of them (video 4). I had never seen a black squirrel.

A black squirrel isn't a separate species but a melanistic (darker) variation of the common Eastern gray squirrel or fox squirrel, caused by a genetic mutation for extra melanin, making them warmer in winter and common in northern areas like Michigan and Ontario. They behave just like gray squirrels but their dark fur offers camouflage in dense forests and better heat absorption in colder climates, making them a localized phenomenon.