Editing Earth's magnetic field (section)

== Biomagnetism ==
{{Main|Magnetoreception}}
Animals, including birds and turtles, can detect the Earth's magnetic field, and use the field to navigate during [[Bird migration|migration]].<ref>{{cite journal |last1=Deutschlander |first1=M. |last2=Phillips |first2=J. |last3=Borland |first3=S. |year=1999 |title=The case for light-dependent magnetic orientation in animals |journal=Journal of Experimental Biology |volume=202 |issue=8 |pages=891–908 |doi=10.1242/jeb.202.8.891 |pmid=10085262 |bibcode=1999JExpB.202..891D }}</ref> Some researchers have found that cows and wild deer tend to align their bodies north–south while relaxing, but not when the animals are under high-voltage power lines, suggesting that magnetism is responsible.<ref name='Burda2009'>{{cite journal |doi=10.1073/pnas.0811194106 |title=Extremely low-frequency electromagnetic fields disrupt magnetic alignment of ruminants |year=2009 |last1=Burda |first1=H. |last2=Begall |first2=S. |last3=Cerveny |first3=J. |last4=Neef |first4=J. |last5=Nemec |first5=P. |journal=Proceedings of the National Academy of Sciences |volume=106 |issue=14 |pages=5708–13 |bibcode=2009PNAS..106.5708B |pmid=19299504 |pmc=2667019|doi-access=free }}</ref><ref name='Nature summary'>{{cite journal |doi=10.1038/458389a |title=Biology: Electric cows |year=2009 |journal=Nature |volume=458 |page=389 |pmid=<!--none--> |issue=7237 |bibcode=2009Natur.458Q.389. |doi-access=free }}</ref> Other researchers reported in 2011 that they could not replicate those findings using different [[Google Earth]] images.<ref>{{cite journal |last1=Hert |first1=J |last2=Jelinek |first2=L |last3=Pekarek |first3=L |last4=Pavlicek |first4=A |year=2011 |title=No alignment of cattle along geomagnetic field lines found |journal=Journal of Comparative Physiology |volume=197 |issue=6 |pages=677–682 |arxiv=1101.5263 |doi=10.1007/s00359-011-0628-7 |pmid=21318402 |s2cid=15520857}} [https://link.springer.com/article/10.1007%2Fs00359-011-0628-7]</ref>

Very weak electromagnetic fields disrupt the magnetic compass used by European robins and other songbirds, which use the Earth's magnetic field to navigate. Neither power lines nor cellphone signals are to blame for the electromagnetic field effect on the birds;<ref>{{Cite journal|last1=Engels|first1=Svenja|last2=Schneider|first2=Nils-Lasse|last3=Lefeldt|first3=Nele|last4=Hein|first4=Christine Maira|last5=Zapka|first5=Manuela|last6=Michalik|first6=Andreas|last7=Elbers|first7=Dana|last8=Kittel|first8=Achim|last9=Hore|first9=P. J.|date=2014-05-15|title=Anthropogenic electromagnetic noise disrupts magnetic compass orientation in a migratory bird|journal=Nature|language=En|volume=509|issue=7500|pages=353–356|doi=10.1038/nature13290|pmid=24805233|issn=0028-0836|bibcode=2014Natur.509..353E|s2cid=4458056|url=https://ora.ox.ac.uk/objects/uuid:5ce377b5-9608-4b88-8f50-3f1476ec6999}}</ref> instead, the culprits have frequencies between 2&nbsp;kHz and 5&nbsp;MHz. These include AM radio signals and ordinary electronic equipment that might be found in businesses or private homes.<ref>{{cite web |url=https://spectrum.ieee.org/electric-field-disruption-magnetic-compass-birds-hints-quantum-action |title=Electromagnetic Interference Disrupts Bird Navigation, Hints at Quantum Action |first=Jeremy |last=Hsu |work=IEEE Spectrum |date=9 May 2014 |access-date=31 May 2015}}</ref>