Thanks to all for commenting. Porcupine seems to be the consensus, though I do have pileated woodpeckers in the yard. I'll set up a game cam and do some searching. We've had a porcupine frequent our yard every summer and he/she has not been a problem, though last year he/she pruned our mulberry tree heavily and I don't want them in the apple trees.
Two 2x4 concrete block arches with three steam trays each
Tapping in Mount Vernon since 2016, 30 to 70 taps, 5/16" tube to 1.5 to 3.5 gallon buckets, some trees on collective gravity tubing to 5 gallon buckets.
Mostly sugar maples, a few reds on 200 year old homestead