There are over 100 species of maple, but only a few are used to make syrup.
Sugar maple is most common, because it has a high concentration of sugar in its sap compared to other maples, like the invasive Norway maple. Norway maples require a higher ratio of sap to syrup, and they’re not usually tapped because they’re not profitable producers of maple syrup.
Scientists observe that red squirrels (Tamiasciurus hudsonicus) exclusively tap sugar maples in forests with sugar maples and red maples. Sugar maple sap has a higher concentration of sugar and carbohydrates, a bigger payoff for their efforts.
But in forests with no sugar maples available, the red squirrel will tap red maples.