Yellow Belllied Sapsucker
This time of year is ideal for sapsuckers. When it's freezing at night and above freezing in the day, the sap flows the most. (It's also a good time for making maple syrup).
The sapsucker opens up many holes in the tree that benefit him and other birds. We've seen red-belied woodpeckers, goldfinch, and chickadees eat either sap or insects from these holes.