Homing pigeons can find their way safely back home over distances of more than a thousand miles. Because birds donít have sat-nav, they have to rely on more natural navigation, such as using the position of the sun as a compass. (c) Alan D. Wilson, www.naturespicsonline.com" alt="Female Mallard in flight" />Itís been known for a while that birds also use the earthís magnetic field to help them find their way, but we donít know much about the actual way in which this works. Scientists have thought for a while that birds like pigeons might have iron-based molecules somewhere in their bodies that respond to the magnetic field. And now Gerta Fleissner and her colleagues at the University of Frankfurt might have found the elusive particles. The researchers found little particles of iron-based maghemite and magnetite in special parts of nerve cells known as sensory dendrites, which are found in the skin lining the upper beak of homing pigeons. Maghemite and magnetite are crystals containing iron oxide compounds, formed by the reaction of iron with oxygen. The researchers found that these dendrites are arranged in complex three-dimensional patterns. The scientists think that this allows birds to get their bearings in three-dimensional space, using the earthís magnetic field to work out where they are. Effectively, they have their own sat-nav in their beaks. Itís also been suggested that this system of nerve cells might also be found in other types of bird, and even some animals that navigate using the earthís magnetic field. And some scientists think that tiny magnetic particles like these could even be used for drug delivery or data storage in the future.