Mistletoe is a parasite: it roots into a branch and drinks from the tree it sits on. In 2012 David Watson and Matthew Herring reported what happened when they took every mistletoe out of seventeen patches of eucalypt woodland in southern Australia and watched them beside patches left alone. Three years on, the cleared woodlands had lost about a fifth of their bird species. The surprise was which birds. It was not mainly the ones that eat mistletoe that went missing but insect-eaters, and the authors’ best guess is the leaves: mistletoe drops a rich litter, and the ground under it feeds more insects. It takes its living from the tree and hands it on, a leaf at a time, to the floor.