The Union-Leader has a good story about UNH research project to study syrup from tree species other than maple. You can read it here.
Apparently this has been a thing for a while, although it’s new to me:
“Our biggest customers are people that are really intrigued by the fact you can get syrup from a lot of different types of trees,” Farrell said. “It’s definitely a niche market and probably always will be.”
Farrell said maple and walnut trees run at the same time, while beech trees can be tapped halfway through maple season when the ground thaws. Birch sap is harvested at the end of maple season.
Farrell said beech syrup has a deeper, bolder flavor than maple syrup while walnut syrup has buttery and nutty notes.
I once drank filtered sap from a black birch tree on our property – not boiled down, so it was very dilute. But it had an interesting sweet flavor.