Chris Packham explores what enables birds of prey to rule the aerial roost. Their ability to dominate their fellow birds in terms of strength, manoeuvrability and phenomenal speed is down to a combination of anatomical and physiological adaptations. Chris explains the internal workings of the bald eagle's ratchet talons and how sharp eyes and a gyroscopic head enable the goshawk to keep its sight firmly fixed on both its prey and its surroundings as it tears through the undergrowth. New research reveals how pop-up feathers on the peregrine falcon's back act like pits on a golf ball to reduce drag — allowing it to reach 220mph.