Sapsuckers remove the outer layer of bark and bore into the cambium, causing the sap to ooze out of the tree, which they drink with their long tongues. Their habit is to return to the same tree over and over and this can cause significant damage to the tree. I liked the pattern so I snapped the photo, although at that time I had never actually seen a sapsucker. Since then I've learned to recognize their *mewing* calls and sometimes find them in my neighbors apple tree. Last spring I had a great look at one outside my office window in a blooming crabapple tree. The are very pretty birds that might easily be mistaken for a downy woodpecker. The yellow-bellied sapsucker has a white wing-stripe and dull yellow underparts that are good field marks.