Editing Magnetoreception (section)

==== In birds ====

[[Homing pigeon]]s use magnetic fields as part of their complex [[Animal navigation|navigation]] system.<ref>{{cite journal |last1=Walcott |first1=C. |year=1996 |title=Pigeon homing: observations, experiments and confusions |journal=[[Journal of Experimental Biology]] |volume=199 |issue=Pt 1 |pages=21–27 |doi=10.1242/jeb.199.1.21 |pmid=9317262 |bibcode=1996JExpB.199...21W }}</ref> [[William Tinsley Keeton|William Keeton]] showed that time-shifted homing pigeons (acclimatised in the laboratory to a different time-zone) are unable to orient themselves correctly on a clear, sunny day; this is attributed to time-shifted pigeons being unable to compensate accurately for the movement of the sun during the day. Conversely, time-shifted pigeons released on overcast days navigate correctly, suggesting that pigeons can use magnetic fields to orient themselves; this ability can be disrupted with magnets attached to the birds' backs.<ref>{{cite journal |last=Keeton |first=W. T. |year=1971 |title=Magnets interfere with pigeon homing |journal=[[PNAS]] |volume=68 |issue=1 |pages=102–106 |pmc=391171 |doi=10.1073/pnas.68.1.102 |pmid=5276278 |bibcode=1971PNAS...68..102K |doi-access=free }}</ref><ref name="Gould, J. L. 1984">{{cite journal |last1=Gould |first1=J. L. |year=1984 |title=Magnetic field sensitivity in animals |journal=[[Annual Review of Physiology]] |volume=46 |pages=585–598 |doi=10.1146/annurev.ph.46.030184.003101 |pmid=6370118 }}</ref> Pigeons can detect magnetic anomalies as weak as 1.86 [[Gauss (unit)|gauss]].<ref name="ReferenceA">{{cite journal |last1=Mora |first1=C. V. |last2=Davison |first2=M. |last3=Wild |first3=J. M. |last4=Walker |first4=M. M. |year=2004 |title=Magnetoreception and its trigeminal mediation in the homing pigeon |journal=[[Nature (journal)|Nature]] |volume=432 |issue=7016 |pages=508–511 |doi=10.1038/nature03077 |pmid=15565156 |bibcode=2004Natur.432..508M |s2cid=2485429 }}</ref>

For a long time the [[Trigeminal nerve|trigeminal]] system was the suggested location for a magnetite-based magnetoreceptor in the pigeon. This was based on two findings: First, magnetite-containing cells were reported in specific locations in the upper beak.<ref name="Fleissner2003" /> However, the cells proved to be immune system [[macrophage]]s, not [[neuron]]s able to detect magnetic fields.<ref name="Treiber2012" /><ref name="Engels 20180124">{{cite journal |last1=Engels |first1=Svenja |last2=Treiber |first2=Christoph Daniel |last3=Salzer |first3=Marion Claudia |last4=Michalik |first4=Andreas |last5=Ushakova |first5=Lyubo v|last6=Keays |first6=David Anthony |last7=Mouritsen |first7=Henrik |last8=Heyers |first8=Dominik |display-authors=3 |date=1 August 2018 |title=Lidocaine is a nocebo treatment for trigeminally mediated magnetic orientation in birds |journal=[[Journal of the Royal Society Interface]] |volume=15 |issue=145 |pages=20180124 |doi=10.1098/rsif.2018.0124 |pmc=6127160 |pmid=30089685}}</ref> Second, pigeon magnetic field detection is impaired by sectioning the trigeminal nerve and by application of [[lidocaine]], an anaesthetic, to the olfactory mucosa.<ref>{{cite journal |last1=Wiltschko |first1=Roswitha |last2=Schiffner |first2=Ingo |last3=Fuhrmann |first3=Patrick |last4=Wiltschko |first4=Wolfgang |date=September 2010 |title=The Role of the Magnetite-Based Receptors in the Beak in Pigeon Homing |journal=[[Current Biology]] |volume=20 |issue=17 |pages=1534–1538 |doi=10.1016/j.cub.2010.06.073 |pmid=20691593 |bibcode=1996CBio....6.1213A |s2cid=15896143 |doi-access=free }}</ref> However, lidocaine treatment might lead to unspecific effects and not represent a direct interference with potential magnetoreceptors.<ref name="Engels 20180124" /> As a result, an involvement of the trigeminal system is still debated. In the search for magnetite receptors, a large iron-containing organelle (the [[cuticulosome]]) of unknown function was found in the inner ear of pigeons.<ref>{{cite journal |last1=Lauwers |first1=Mattias |last2=Pichler |first2=Paul |last3=Edelman |first3=Nathaniel Bernard |last4=Resch |first4=Guenter Paul |last5=Ushakova |first5=Lyubov |last6=Salzer |first6=Marion Claudia |last7=Heyers |first7=Dominik |last8=Saunders |first8=Martin |last9=Shaw |first9=Jeremy |display-authors=3 |date=May 2013 |title=An Iron-Rich Organelle in the Cuticular Plate of Avian Hair Cells |journal=[[Current Biology]] |volume=23 |issue=10 |pages=924–929 |doi=10.1016/j.cub.2013.04.025 |pmid=23623555  |bibcode=1996CBio....6.1213A|s2cid=9052155 |doi-access=free }}</ref><ref>{{cite journal |last1=Nimpf |first1=Simon |last2=Malkemper |first2=Erich Pascal |last3=Lauwers |first3=Mattias |last4=Ushakova |first4=Lyubov |last5=Nordmann |first5=Gregory |last6=Wenninger-Weinzierl |first6=Andrea |last7=Burkard |first7=Thomas R |last8=Jacob |first8=Sonja |last9=Heuser |first9=Thomas |display-authors=3 |date=15 November 2017 |title=Subcellular analysis of pigeon hair cells implicates vesicular trafficking in cuticulosome formation and maintenance |journal=[[eLife]] |volume=6 |doi=10.7554/elife.29959 |pmc=5699870 |pmid=29140244 |doi-access=free }}</ref> Areas of the pigeon brain that respond with increased activity to magnetic fields are the posterior [[vestibular nuclei]], [[dorsal thalamus]], [[hippocampus]], and [[Avian pallium|visual hyperpallium]].<ref>{{cite journal |last1=Wu |first1=L.-Q. |last2=Dickman |first2=J. D. |year=2011 |title=Magnetoreception in an avian brain in part mediated by inner ear lagena |journal=[[Current Biology]] |volume=21 |issue=5 |pages=418–23 |doi=10.1016/j.cub.2011.01.058 |pmid=21353559 |pmc=3062271 |bibcode=2011CBio...21..418W }}</ref>

[[Chicken|Domestic hens]] have iron mineral deposits in the sensory [[dendrites]] in the upper beak and are capable of magnetoreception.<ref name="Falkenberg2010" /><ref name="Wiltschko et al., 2007">{{cite journal |last1=Wiltschko |first1=Wolfgang |last2=Freire |first2=Rafael |last3=Munro |first3=Ursula |last4=Ritz |first4=Thorsten |last5=Rogers |first5=Lesley |last6=Thalau |first6=Peter |last7=Wiltschko |first7=Roswitha |title=The magnetic compass of domestic chickens, ''Gallus gallus'' |journal=[[Journal of Experimental Biology]] |volume=210 |issue=13 |date=1 July 2007 |doi=10.1242/jeb.004853 |pages=2300–2310 |pmid=17575035 |bibcode=2007JExpB.210.2300W |s2cid=9163408 |hdl=10453/5735 |hdl-access=free }}</ref> Beak trimming causes loss of the magnetic sense.<ref name="Freire et al., 2011">{{cite journal |last1=Freire |first1=R. |last2=Eastwood |first2=M. A. |last3=Joyce |first3=M. |year=2011 |title=Minor beak trimming in chickens leads to loss of mechanoreception and magnetoreception |journal=[[Journal of Animal Science]] |volume=89 |issue=4 |pages=1201–1206 |doi=10.2527/jas.2010-3129 |pmid=21148779 }}</ref>