What is the functional role ascribed to the specialized tongue within the Picidae family?

To probe deep into tunnels to extract insects

The morphology of the tongue and bill works in concert as a sophisticated toolset for the wood-excavating lifestyle characteristic of the Picidae family. While the bill functions as a sturdy chisel to break through the wood surface, the tongue performs the delicate extraction work. It is described as being incredibly specialized, often featuring barbs at the tip. This structure allows the bird to efficiently probe deep into the tunnels and galleries created by insects within the wood, reaching and extracting prey that would otherwise be inaccessible. This highly adapted probing mechanism, along with the stiff tail brace and specialized feet, solidifies the anatomical blueprint for the entire family.