Sap sucker diet
Sapsuckers are the only woodpeckers that don’t drill into trees looking for insects, but insects are a part of their diet. Often insects are drawn to their sap wells and the birds take advantage of them while using the brush like (think paint brush) structure on the end of their tongue to ingest the nutritious sap.
However, like many birds, they also enjoy fruits and berries which are a consistent part of their diet, especially in winter only xylem sap, mostly water, is what’s available. The insects attracted to their sapwells are especially important for adult birds to feed to their young; ornithologist have watched sap suckers dip these insects into sap before returning to their nest. Their bills, fortunately, are remarkably strong as males not only drill out nesting cavities but mark territory by hammering away on metal signs.