Editing Bird migration (section)

==Nocturnal migratory behaviour ==

During nocturnal migration ("nocmig"<ref>{{cite web |title=Nocmig: A beginner's guide |url=https://www.bto.org/community/blog/nocmig-beginners-guide |publisher=[[British Trust for Ornithology]] |access-date=8 March 2022 |language=en |date=3 December 2019}}</ref>), many birds give nocturnal flight calls, which are short, contact-type calls.<ref name=":02">{{Cite journal |last=Farnsworth |first=Andrew |date=2005-07-01 |title=Flight calls and their value for future ornithological studies and conservation research |journal=The Auk |volume=122 |issue=3 |pages=733–746 |doi=10.1642/0004-8038(2005)122[0733:FCATVF]2.0.CO;2 |s2cid=85954703 |issn=0004-8038|doi-access=free }}</ref> These likely serve to maintain the composition of a migrating flock, and can sometimes encode the sex of a migrating individual,<ref>{{Cite journal |last1=Griffiths |first1=Emily T. |last2=Keen |first2=Sara C. |last3=Lanzone |first3=Michael |last4=Farnsworth |first4=Andrew |date=2016-06-10 |title=Can Nocturnal Flight Calls of the Migrating Songbird, American Redstart, Encode Sexual Dimorphism and Individual Identity? |journal=PLOS ONE |volume=11 |issue=6 |pages=e0156578 |doi=10.1371/journal.pone.0156578 |pmid=27284697 |pmc=4902225 |bibcode=2016PLoSO..1156578G |issn=1932-6203|doi-access=free }}</ref> and to avoid collision in the air.<ref name=":02"/> Nocturnal migration can be monitored using weather radar data,<ref>{{Cite journal |last1=Farnsworth |first1=Andrew |last2=Van Doren |first2=Benjamin M. |last3=Hochachka |first3=Wesley M. |last4=Sheldon |first4=Daniel |last5=Winner |first5=Kevin |last6=Irvine |first6=Jed |last7=Geevarghese |first7=Jeffrey |last8=Kelling |first8=Steve |date=2016-04-01 |title=A characterization of autumn nocturnal migration detected by weather surveillance radars in the northeastern USA |journal=Ecological Applications |volume=26 |issue=3 |pages=752–770 |doi=10.1890/15-0023 |pmid=27411248 |bibcode=2016EcoAp..26..752F |s2cid=44942398 |issn=1939-5582}}</ref> allowing ornithologists to estimate the number of birds migrating on a given night, and the direction of the migration.<ref>{{Cite journal |last1=Dokter |first1=Adriaan M. |last2=Liechti |first2=Felix |last3=Stark |first3=Herbert |last4=Delobbe |first4=Laurent |last5=Tabary |first5=Pierre |last6=Holleman |first6=Iwan |date=2011-01-06 |title=Bird migration flight altitudes studied by a network of operational weather radars |journal=Journal of the Royal Society Interface |volume=8 |issue=54 |pages=30–43 |doi=10.1098/rsif.2010.0116 |issn=1742-5689 |pmid=20519212 |pmc=3024816}}</ref> Future research includes the automatic detection and identification of nocturnally calling migrant birds.<ref>{{Cite journal |last1=Salamon |first1=Justin |last2=Bello |first2=Juan Pablo |last3=Farnsworth |first3=Andrew |last4=Robbins |first4=Matt |last5=Keen |first5=Sara |last6=Klinck |first6=Holger |last7=Kelling |first7=Steve |date=2016-11-23 |title=Towards the Automatic Classification of Avian Flight Calls for Bioacoustic Monitoring |journal=PLOS ONE |volume=11 |issue=11 |pages=e0166866 |doi=10.1371/journal.pone.0166866 |pmid=27880836 |pmc=5120805 |bibcode=2016PLoSO..1166866S |issn=1932-6203|doi-access=free }}</ref>

Nocturnal migrants land in the morning and may feed for a few days before resuming their migration. These birds are referred to as ''passage migrants'' in the regions where they occur for a short period between the origin and destination.<ref>{{cite journal |last=Schmaljohann |first=Heiko |author2=Felix Liechti |author3=Bruno Bruderer |year=2007 |title=Songbird migration across the Sahara: the non-stop hypothesis rejected! |journal=[[Proceedings of the Royal Society B]] |volume=274 |issue=1610 |pages=735–739 |doi=10.1098/rspb.2006.0011 |pmc=2197203 |pmid=17254999}}</ref>

Nocturnal migrants minimize depredation, avoid overheating and can feed during the day.<ref name="LincolnInf-A001" /> One cost of nocturnal migration is the loss of sleep. Migrants may be able to alter their quality of sleep to compensate for the loss.<ref>{{cite journal |last=Rattenborg |first=N. C. |author2=Mandt, B. H. |author3=Obermeyer, W. H. |author4=Winsauer, P. J. |author5=Huber, R. |year=2004 |title=Migratory Sleeplessness in the White-Crowned Sparrow (Zonotrichia leucophrys gambelii) |journal=PLOS Biol. |volume=2 |issue=7 |page=e212 |doi=10.1371/journal.pbio.0020212 |pmc=449897 |pmid=15252455 |doi-access=free }}</ref>