Actually birch beer was a old Russian thing for centuries. They killed off whole forests of it over tapping for birch beer before anybody though of syrup. It's supposed to have some kind of health benifits also. Makes a different kind of syrup. The trees over there look like our paper birch.
By hanging on do you mean they look sick or is the bark sort of shaggy on them. The shaggy part is normal. I have a yellow birch that must be 4 feet across at the bottom. has to be the mommy to all the others in the woods. I put a tap in it and filled a 5 gallon pail a day off of it. All of them run well. I have paper and sweet birch but can't seem to get sap out of the sweet birch.