Hummingbirds, native to North and South America, are among the smallest and most agile birds in the world. Often barely larger than a thumb, they are the only bird species that can fly not only forwards, but also backwards or sideways. Their characteristic hovering flight makes that possible. However, hovering is extremely energy-demanding. In a genomic study published in the journal Science, an international team of scientists led by Prof. Michael Hiller at the LOEWE Centre for Translational Biodiversity Genomics (LOEWE-TBG) in Frankfurt, Germany, investigated the evolutionary adaptations of the metabolism that may have enabled the hummingbirds‘ unique flying abilities.