Q.River Birch – Need ID And Solution Of Damage
3-trunk River Birch tree about 16′ tall, just purchased and planted last fall, didn’t notice anything unusual when I purchased or planted it; or even over the winter. New sap/clear ooze seeping from one trunk. Scars are on two of the three trunks. Scars go all the way around each trunk. Thank you in advance.

Certified GKH Gardening Expert
Unfortunately, your photo did not come through. I will not be able to identify the issue in question. Commonly, insects or borers will cause this, but it can be bacterial as well.
Here is an article that will help you with the general care of the tree, in the meantime:
https://www.gardeningknowhow.com/ornamental/trees/birch/planting-river-birch-trees.htm

Certified GKH Gardening Expert
Did you do any pruning in late winter? That can cause oozing, which is normal. Wait till the leaves have emerged to prune.
Are the scars like woodpecker damage or insect borers all around or tree girdling?
Here is information on those:
https://www.gardeningknowhow.com/ornamental/trees/tgen/how-to-fix-girdled-trees.htm
https://www.gardeningknowhow.com/plant-problems/pests/animals/woodpecker-damage-trees.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/tree-borer-insects.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/what-is-tree-sap.htm