Woodpeckers are the most proficient builders in the avian world. Whether spotted, green or black woodpecker, they hammer away at trees to build more cavities than they actually need. Among those who benefit from this construction zeal are tits, pigeons, pygmy owls, squirrels and other animals that make their home in tree hollows. Searching for a mate sees the woodpecker peck away at amazing speeds, sometimes even on metal. In choosing their homes, great spotted woodpeckers are quite inventive. But woodpecker holes in insulated façades usually don’t go down well with the house’s owner or its animal squatters.