NZ scientists crack puzzle of pigeons

A pigeon's ability to find its way home from distant and unfamiliar locations, even after it has been drugged, has been explained for the first time by two New Zealand scientists.

Researchers found that homing pigeons returned home by a sort of ingrained GPS system, responding to markers on the Earth's magnetic field.

Scientists have shown that pigeons are sensitive to the magnetic field, but until now none have determined exactly how the birds use the field to work out their position.

Professor Michael Walker and Dr Cordula Mora of the University of Auckland reviewed the homing behaviour of pigeons returning to three lofts in Germany.

They mapped the birds' direction when they left home against the intensity of magnetic fields in the area.

Professor Walker, of the university's Maori Centre of Research Excellence, said researchers had often been puzzled by pigeons taking an indirect line home. The birds later established a course towards home and updated these courses en route.

He said their work found that pigeons could chart their course home from the outset by responding to local variations, or ripples, in the surface of the area's magnetic field. Even pigeons taken under anaesthesia to distant locations showed themselves adept at finding a way home.

Professor Walker said the study had strong significance because it provided evidence in support of a model for use of the Earth's magnetic field to determine the magnetic equivalents of latitude and longitude."[This is] a geomagnetic positioning system invented long before the GPS satellites were launched into space."

The study was published internationally this week in the Proceedings of the Royal Society journal.