Editing Bird migration (section)

===Orientation and navigation===
[[File:Bar-tailed Godwit migration.jpg |thumb |300px |The routes of satellite tagged [[bar-tailed godwit]]s migrating north from [[New Zealand]]. This species has the longest known non-stop migration of any species, up to {{convert|10200|km|nmi|round=50|abbr=on}}.]]
{{Main |Animal navigation}}
[[Animal navigation|Navigation]] is based on a variety of senses. Many birds have been shown to use a sun compass. Using the Sun for direction involves the need for making compensation based on the time. Navigation has been shown to be based on a combination of other abilities including the ability to detect magnetic fields ([[magnetoreception]]), use visual landmarks as well as [[olfactory navigation|olfactory cues]].<ref name=walraffpigeon>{{cite book |last=Walraff |first=H. G. |year=2005 |title=Avian Navigation: Pigeon Homing as a Paradigm |publisher=Springer}}</ref>

Long-distance migrants are believed to disperse as young birds and form attachments to potential breeding sites and to favourite wintering sites. Once the site attachment is made they show high site-fidelity, visiting the same wintering sites year after year.<ref>{{cite book |last1=Ketterson |first1=E. D. |last2=Nolan | first2=V. Jr. |year=1990 |chapter=Site attachment and site fidelity in migratory birds: experimental evidence from the field and analogies from neurobiology |title=Bird Migration |editor=E. Gwinner |publisher=Springer |pages=117–129 |chapter-url=http://www.indiana.edu/~kettlab/ellen/pubs/KettersonNolan1990.pdf |archive-url=https://web.archive.org/web/20090614142136/http://www.indiana.edu/%7Ekettlab/ellen/pubs/KettersonNolan1990.pdf |archive-date=2009-06-14 |url-status=dead}}</ref>

The ability of birds to navigate during migrations cannot be fully explained by endogenous programming, even with the help of responses to environmental cues. The ability to successfully perform long-distance migrations can probably only be fully explained with an accounting for the cognitive ability of the birds to recognize habitats and form mental maps. [[Satellite tracking (animal migration)|Satellite tracking]] of day migrating raptors such as ospreys and honey buzzards has shown that older individuals are better at making corrections for wind drift.<ref name = migrating>{{cite journal |author1=Thorup, Kasper |author2=Thomas Alerstam |author3=Mikael Hake |author4=Nils Kjelle |year=2003 |title=Bird orientation: compensation for wind drift in migrating raptors is age dependent |journal=[[Proceedings of the Royal Society B]] |volume=270 |pages=S8–S11 |doi=10.1098/rsbl.2003.0014 |pmid= 12952622 |pmc=1698035 |issue=Suppl 1}}</ref> Birds rely for navigation on a combination of innate biological senses and experience, as with the two [[Electromagnetism|electromagnetic]] tools that they use. A young bird on its first migration flies in the correct direction according to the Earth's [[magnetic field]], but does not know how far the journey will be. It does this through a [[radical pair mechanism]] whereby chemical reactions in special [[biological pigment|photo pigments]] sensitive to short wavelengths are affected by the field. Although this only works during daylight hours, it does not use the position of the Sun in any way. With experience, it learns various landmarks and this "mapping" is done by [[magnetite]]s in the [[trigeminal system]], which tell the bird how strong the field is. Because birds migrate between northern and southern regions, the magnetic field strengths at different [[latitude]]s let it interpret the radical pair mechanism more accurately and let it know when it has reached its destination.<ref>{{cite journal |last=Wiltschko |first=W. |author2=U. Munro |author3=H. Ford |author4=R. Wiltschko |year=2006 |title=Bird navigation: what type of information does the magnetite-based receptor provide? |journal=[[Proceedings of the Royal Society B]] |volume=273 |pages=2815–20 |doi=10.1098/rspb.2006.3651 |pmid=17015316 |issue=1603 |pmc=1664630}}</ref> There is a neural connection between the eye and "Cluster N", the part of the forebrain that is active during migrational orientation, suggesting that birds may actually be able to ''see'' the magnetic field of the Earth.<ref>{{cite journal |last1=Heyers |first1=D. |last2=Manns |first2=M. |others=Luksch. H; Güntürkün, O; Mouritsen, H. |year=2007 |title=A Visual Pathway Links Brain Structures Active during Magnetic Compass Orientation in Migratory Birds |journal=PLOS ONE |volume=2 |issue=9 |page=e937 |doi=10.1371/journal.pone.0000937 |pmid=17895978 |pmc=1976598 |bibcode=2007PLoSO...2..937H |editor1-last=Iwaniuk |editor1-first=Andrew|doi-access=free }}</ref><ref>{{cite journal |last=Deutschlander |first=M. E. |author2=Phillips, J. B. |author3=Borland, SC |year=1999 |title=The case for light-dependent magnetic orientation in animals |journal=Journal of Experimental Biology |volume=202 |pages=891–908 |url=http://jeb.biologists.org/cgi/reprint/202/8/891 |issue=8 |doi=10.1242/jeb.202.8.891 |pmid=10085262|bibcode=1999JExpB.202..891D |url-access=subscription }}</ref>