Using your beak to excavate a home in a pine tree takes a lot of time and hammering, as every red-cockaded woodpecker knows. These endangered woodpeckers (Picoides borealis, shown above) are the only bird that chooses living rather than dead trees for their excavations. The job is a big one, because each family member needs a roost of his/her own, requiring between 1 year and a decade to complete. Wood-decaying fungi can speed up the work, but only if they find their way into a wound in the bark. Do the woodpeckers and fungi have a symbiotic relationship, with the birds helping the fungi disperse while the fungi assist their excavations by softening the wood? To find out, scientists drilled 5.1-centimeter holes into the central wood of 60 pines in a forest in coastal North Carolina. The researchers screened off half the holes, but left the other 30 open. Twenty-six months later, woodpeckers had worked on 26 of these 30 cavities, the scientists report today in the Proceedings of the Royal Society B. And they’d brought along their assistants: the wood-decaying fungi. The scientists found that whereas only 27% of the trees had been infected with these organisms at the beginning of the experiment, now 75% were. The diversity of wood-decay fungi had also increased dramatically. These were similar to those the researchers found on the woodpeckers’ beaks, wings, and feet, and in cavities the birds excavated naturally—unlike those in the screened holes, which also had fewer types. Thus, red-cockaded woodpeckers and their fungi pals work together to re-engineer the forest—providing homes not only for themselves, but many species, such as songbirds, flying squirrels, insects, snakes, and amphibians, in need of a home inside a tree.