How are woodpeckers related to toucans?

Woodpeckers and toucans are related through their classification in the order Piciformes, a group of arboreal birds that share specific anatomical characteristics, most notably a zygodactylous foot (where two toes point forward and two point backward).123

Within this order, both families belong to the suborder Pici. Evolutionary studies indicate that these families are interrelated:3
* Shared Ancestry: Woodpeckers and barbets share a common ancestor, as do barbets and toucans.4
* Morphological Connections: While woodpeckers and toucans have evolved highly specialized, distinct features—such as the woodpecker's shock-absorbing skull and the toucan's large, serrated bill—they remain linked by their placement within the Pici suborder, which generally features feathered oil glands and specific skeletal structures.23
* Ecological Interaction: Their relationship is also functional; toucans often nest in natural tree cavities or in holes previously excavated by woodpeckers, as toucans do not excavate their own nesting sites.3