If you make loud hooting calls on Lord Howe Island, 300 miles off the coast of Australia, providence petrels fall from the sky. They are curious and still unafraid of humans who only arrived on the island around 200 years ago. The petrels are very ungainly on land and squabble with each other, but are very friendly towards people. Petrels have a tubenose, a structure that it shares with other ocean going birds and which is crucial to its survival on the open ocean. The tube channels air to a sense organ at the very base of the beak that can detect very faint odours. This is a rare ability amongst birds and enables the tubenoses to find floating food from very great distances. This is why cape petrels and sooty shearwaters come flocking when David Attenborough throws a bucket of smelly fish oil overboard. Not only can they smell fish oil or offal, they can also find shrimps and other small creatures. This is because when shrimp feed on floating plants, the plants give off a gas that smells a bit like rotting seaweed. The petrels can detect even the faintest whiff and that tells them where to find the shrimp.