On Nicobar Island, in the Indian Ocean, a most unusual hunting party is searching for food. Through the branches of the forest, the tiny Nicobar treeshrew scuttles about searching for insects. They’re followed by the racket-tailed drongo, a small bird that picks off juicy morsels flushed out by the foraging treeshrews. So far, this isn’t unusual – many distantly related animals forage together, either because they net more food or because they can watch out for predators.

But this alliance has a third an altogether more surprising member – a sparrowhawk. This bird of prey is five times larger than either of the other two species and can easily kill treeshrews. But it doesn’t – instead, it only deploys