A vampire bat that fails to find blood two or three nights in a row can starve to death. Well-fed roostmates then regurgitate part of their meal to feed it. The sharing isn't random: vampires give more to those who have helped them before. It is one of the best-documented examples of reciprocity among animals.
In 2022, a young tagged bar-tailed godwit flew from Alaska to Tasmania in about 11 days of nonstop flight, covering 13,560 km without eating, drinking or landing. Before departure, these birds pile on huge fat reserves and shrink their digestive organs, which are useless during the journey.
To escape rivals, a dung beetle rolls its ball of dung in a straight line. At night, it holds its course using the glowing band of the Milky Way. In a planetarium, researchers showed that beetles rolled straight under a starry sky but wandered aimlessly when the galaxy was switched off. It was the first animal known to navigate this way.