Its hard to tell you how, but the Sugar Maple, a lot of times will be jet black on trunk where something has broke the bark and the sap has run down and soaked it over the years ,I can't think of another tree that does that .Probably sapsucker damage resulting in sap leaking down the trunk and a black fungus growing on the sap. If you see rows of holes in the trunk above the blackened area, that is probably what's going on. Here is a tree leaking sap. Maybe this will help.And when I'm tapping if I run up on a Silver Maple I tap it . We're lucky we probably have five hundred trees but I'm too old to start a Sugar operation,just do it as a hobby and get enough syrup for our use.
Here is another Pic of frequent visitor thats close to the house,He's eating a deer .