A young homing pigeon must learn quickly how to find its way home from the strange neighborhoods where humans insist on leaving it. At first the bird does this by relying on its crudest instincts, returning to its roost along a route full of youthful zigzags. Over time, though, it refines its methods. A mature pigeon takes a much simpler route, because it has drawn itself a more complex map.
Homing pigeons have been subjected to all kinds of research. The latest study used GPS devices, which the birds carried in little Teflon backpacks. Ingo Schiffner of the Queensland Brain Institute and Roswitha Wiltschko of Goethe-Universität Frankfurt studied pigeons at three different ages: juveniles (6 to 7 months old), yearlings (the same pigeons in their second year of life, after going through a training program), and older trained birds (at least two years of age).
Wearing their tracking harnesses, the birds were released from various sites that ranged from 3.2 to 23.5 kilometers away from their home loft in Frankfurt, Germany. Here are the routes some of the birds took when returning to their home (the square) from a release site 6.8 kilometers away (the triangle):
Attaching GPS devices to animals is currently trendy; there’s a whole new journal dedicated to the subject. But humans have a long history of rigging our technologies to pigeons. At the start of the 20th century, German apothecary Julius Neubronner designed and patented a little camera on a harness for homing pigeons to carry (he had previously used the birds to ferry prescriptions and drugs for his patients).
The German military toyed with using Neubronner’s pigeon-camera technology for reconnaissance during World War I. With the cameras hooked to timers, the birds could take pictures above enemy lines and carry them back home. These days we’re attaching our instruments to the accommodating birds not for the sake of spying on our enemies, but to decode the secrets of the pigeons themselves.
Images: Homing pigeons by Amanda Dague (via Flickr); figure from Schiffner and Wiltschko; pigeon cameras by Julius Neubronner (via Wikimedia Commons).
Schiffner, I., & Wiltschko, R. (2013). Development of the navigational system in homing pigeons: increase in complexity of the navigational map Journal of Experimental Biology DOI: 10.1242/jeb.085662