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 its talons on other prey that are disturbed by its partners.
Predator and prey species don't usually fraternise with each other outside the confines of animated films, but this alliance is ...
