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SUBTLE SIGNAL. “The problem for a bird wanting to use a magnetic map is that the average change in magnetic field intensity is only c. 3 nT/km on the North-South axis: The geomagnetic field changes c. 30,000 nT from one of the magnetic poles to the magnetic equator, which are c. 10,000km apart. Likewise, magnetic inclination changes only c. 0.009°/km along the North-South axis (a 90° change over 10,000km).” https://lnkd.in/eUbuD-a View in LinkedIn

MULTIFACTORIAL. “One thing is for sure; the natural map sense of birds is multifactorial. It relies on input from olfaction and vision and possibly also from magnetic sensing and maybe even from hearing. Pigeons with opaque lenses that prevented them from detecting any local visual landmarks can return to within c. 5 km of their loft.” https://lnkd.in/eUbuD-a View in LinkedIn

RADICAL PAIR. “When the Radical Pair Model was put forward, applying radio-frequency magnetic fields in the MHz range was suggested as a diagnostic tool. The respective experiments supported the model: adding such fields to the geomagnetic field disrupted magnetic compass orientation in several species of birds.” http://rsif.royalsocietypublishing.org/content/12/103/20141103.full View in LinkedIn

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NEW TOOLS. “Despite a wealth of behavioural evidence that provides compelling support for magnetic field perception in animals, the cellular and molecular basis for this sense remains to be discovered and characterized. The reasons why the location, structure and function of magnetoreceptor cells have remained hidden to this point are many, but with the advent of new characterization methods and innovative experimental approaches many research tools now exist for resolving this long-standing biological question.” http://rsif.royalsocietypublishing.org/content/12/110/20150499.full View in LinkedIn

CHEMICAL SPIN. “These properties of the avian magnetic compass remained enigmatic until the Radical Pair Model provided a possible explanation. The model, described in detail by Ritz et al. proposes that the avian magnetic compass is based on spin-chemical processes in specialized photopigments.” http://rsif.royalsocietypublishing.org/content/12/103/20141103.full View in LinkedIn

STELLAR VS COMPASS. “The brain region Cluster N is necessary for magnetic compass orientation behavior, but not for star and Sun compass orientation. The trigeminal nerve is neither necessary nor sufficient for magnetic compass orientation in European robins.” https://lnkd.in/eUbuD-a View in LinkedIn

TWO MECHANISMS. “On the basis of current scientific evidence, iron-mineral-based magnetoreception and radical-pair-based magnetoreception mechanisms seem to exist in birds, but they seem to be used for different purposes.” https://lnkd.in/eUbuD-a View in LinkedIn

QUANTUM CHEMISTRY. “A light-sensitive molecule (D) absorbs light and uses the light energy to transfer an electron to an acceptor (A); thereby, a radical pair is produced. If this radical pair is long-lived (>1 μs), then it can, depending on the spin of the electrons, exist in one of two states—a singlet state (spins antiparallel) or a triplet state (spins parallel). It is known from chemistry that singlet and triplet states have different chemical properties; thus, they often result in different chemical end products. Earth-strength magnetic fields can theoretically affect this statistical equilibrium and thereby modulate a presently unknown biochemical pathway.” https://lnkd.in/eUbuD-a View in LinkedIn