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Several migratory animal species use the magnetic field of the earth to navigate during migration. In particular, this includes birds which migrate nocturnally, some species of fish, and the North American monarch butterfly. These species are less able to use visual navigation. However, there is debate about the mechanism by which this internal compass works.


The two leading theories of magnetoreception can be categorised as a magnetite-based system which has been found to be involved most significantly in bacteria.The second, more complex proposed mechanism suggests that select biological molecules can generate radical pairs which are sensitive to the Earth’s magnetic field [1]. Suggested by Thorsten Ritz et al. [2], this was posited as a theoretical model that has since been inspiration for several in vivo studies.

Behavioural experiments by Wolfgang and Roswitha Wiltschko in the European robin model seems to complement this proposed mechanism of the radical pair mechanism of the avian compass [3]. However, though theoretically compelling, this mechanism still lacks the conclusive empirical biological evidence of the fundamental understanding of the mechanism behind the avian compass.

Research team

University of Surrey

Brendan Howlin profile image

Professor Brendan Howlin

Professor of Computational Chemistry

Youngchan Kim profile image

Dr Youngchan Kim

Lecturer in Quantum Biology

Johnjoe McFadden profile image

Professor Johnjoe McFadden

Professor of Molecular Genetics, Associate Dean (International)

External collaborators

Jose Jimenez

Dr Jose Jimenez Zarco

Senior Lecturer in Synthetic Biology - Imperial College London

Dr Alex Jones

Principal Research Scientist - National Physical Laboratory

Dr Daniel Kattnig

Senior Lecturer - University of Exeter

Professor Alexandra Olaya-Castro

Professor of Physics - University College London


[1] Hore PJ, Mouritsen H. The radical-pair mechanism of magnetoreception. Annual review of biophysics. 2016 Jul 5;45:299-344.

[2] Ritz T, Adem S, Schulten K. A model for photoreceptor-based magnetoreception in birds. Biophysical journal. 2000 Feb 1;78(2):707-18.

[3] Ritz T, Wiltschko R, Hore PJ, Rodgers CT, Stapput K, Thalau P, Timmel CR, Wiltschko W. Magnetic compass of birds is based on a molecule with optimal directional sensitivity. Biophysical journal. 2009 Apr 22;96(8):3451-7.

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