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Pigeons’ homing skill not down to iron-rich beak cells

11 April 2012

The theory that pigeons’ famous skill at navigation is down to iron-rich magnetic nerve cells in their beaks has been disproved by a new study published in Nature. (PDF)

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 continued: “We had hoped to find magnetic nerve cells, 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 as they do not produce electrical signals unlike nerve cells. “We found a startling diversity in the location and number of iron-rich cells in the pigeon beak. Some birds had just 200, while others had over 100,000” said Dr Keays, “it just didn’t make sense that these cells were the bird’s sat-nav system”.

Dr Keays’s lab, based at the Institute of Molecular Pathology in Vienna, worked together with Dr Shaw from the University of Western Australia, and Drs Lythgoe and Riegler from the UCL Centre for Advanced Biomedical Imaging in London.

“We employed state-of-the-art imaging techniques to visualise and map the location of iron-filled cells in the pigeon beak” said Dr Mark Lythgoe.

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.

Image: State-of-the-art imaging techniques were used to create detailed maps of the pigeon beak. The yellow structures were imaged using micro-computed tomography (microCT), which is used to capture dense structures like bone. The purple structures were produced with magnetic resonance imaging (MRI), showing the external soft tissues.

“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.

Video: A series of anatomical landmarks were used to align the histology with the MRI image. Video: State-of-the-art imaging at the UCL Centre for Advanced Biomedical Imaging revealed detailed MRI maps of the pigeon beak.
 
  • For more information or to speak to Dr David Keays, Institute of Molecular Pathology, Vienna, phone +43(1) 79730-3530, email: keays@imp.ac.at
  • To contact Dr Mark Lythgoe, Director, UCL Centre for Advanced Biomedical Imaging, email: m.lythgoe@ucl.ac.uk
  • Alternatively, please contact Clare Ryan, UCL Media Relations, phone: 07797 565 056, email: clare.ryan@ucl.ac.uk, Out of hours: + 44 (0)7917 271364.
  • ‘Clusters of iron-rich cells in the upper beak of pigeons are macrophages not magnetosensitive neurons’ is published online in Nature today. Copies are available from UCL Media Relations.
 

Media Coverage:

Science News:

Pigeon navigation finding called off-course.

New Scientist:

Mystery of bird navigation system still unsolved.

International Business Times:

Pigeons Aren’t Led By Their Beaks? New Study Ruffles Some Feathers.

Page last modified on 14 oct 13 20:30