Magnetic navigation – putting the cat among the pigeons
Pigeons are famed for their homing ability. Until now, scientists believed they detected the Earth’s magnetic field using iron rich nerves in their beaks. However, research published today in Nature shows that this is not the case. The study shows that iron-rich cells in the pigeon beak are in fact specialised white blood cells, called macrophages. This finding, which shatters the established dogma, puts the field back on course as the search for magnetic cells continues.
“The mystery of how animals detect magnetic fields, has just got more mysterious” said Dr David Keays who led the study. Dr Keays’s lab, based at the Research Institute of Molecular Pathology in Vienna, worked together with Dr Shaw from the University of Western Australian and Dr Mark Lythgoe from the UCL Centre for Advanced Biomedical Imaging. Together they employed state-of-the-art imaging techniques to visualise and map the location of iron rich cells in the pigeon beak.
“We had hoped to find nerves with magnetic crystals” said Dr Keays “but unexpectedly we found thousands of macrophages, each filled with tiny balls of iron.” Macrophages are a type of white blood cell that play a vital role in defending against infection and re-cycling iron from red blood cells, “but they’re unlikely to be involved in magnetic sensing“ explained Dr Keays.
The search for the actual mechanism that allows migratory birds, and many other animals, to respond to the Earth's magnetic field and navigate around their environment remains an intriguing puzzle to be solved.
“We have no idea how big the puzzle is or what the picture looks like, but today we’ve been able to remove those pieces that just didn’t fit“ said Dr Keays.
(Courtesy of Michael Sinclair-Jones, University of Western Australia)
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The paper „Clusters of iron-rich cells in the upper beak of pigeons are macrophages not magnetosensitive neurons“ was published online in Nature on April 11, 2012 (doi:10.1038/nature11046).
Dr Heidemarie Hurtl
Phone: +43 1 79730 3625
Dr David Keays
Institute of Molecular Pathology, Vienna
Phone: +43 1 79730-3530