Editing Bird migration (section)

==Short-distance and altitudinal migration==
[[File:Cedar Waxwing-27527-1.jpg |right |thumb |[[Cedar waxwing]]]]
{{Main |Altitudinal migration}}
Many long-distance migrants appear to be genetically programmed to respond to changing day length. Species that move short distances, however, may not need such a timing mechanism, instead moving in response to local weather conditions. Thus mountain and moorland breeders, such as [[wallcreeper]] ''Tichodroma muraria'' and [[white-throated dipper]] ''Cinclus cinclus'', may move only altitudinally to escape the cold higher ground. Other species such as [[Merlin (bird)|merlin]] ''Falco columbarius'' and [[Eurasian skylark]] ''Alauda arvensis'' move further, to the coast or towards the south. Species like the chaffinch are much less migratory in [[Great Britain|Britain]] than those of continental Europe, mostly not moving more than 5&nbsp;km in their lives.<ref>{{cite web |url=http://sounds.bl.uk/environment/british-wildlife-recordings/022m-w1cdr0001384-0700v0 |title=British Wildlife Recordings: Chaffinch |publisher=British Library |access-date=10 April 2014 |archive-date=13 April 2014 |archive-url=https://web.archive.org/web/20140413155213/http://sounds.bl.uk/environment/british-wildlife-recordings/022m-w1cdr0001384-0700v0 |url-status=dead }}</ref>

Short-distance passerine migrants have two evolutionary origins. Those that have long-distance migrants in the same family, such as the [[common chiffchaff]] ''Phylloscopus collybita'', are species of southern hemisphere origins that have progressively shortened their return migration to stay in the northern hemisphere.<ref>Cocker, 2005. p. 378</ref>

Species that have no long-distance migratory relatives, such as the [[waxwing]]s ''Bombycilla'', are effectively moving in response to winter weather and the loss of their usual winter food, rather than enhanced breeding opportunities.<ref name=CockerWaxwing>Cocker, 2005. p. 326</ref>

In the tropics there is little variation in the length of day throughout the year, and it is always warm enough for a food supply, but altitudinal migration occurs in some tropical birds. There is evidence that this enables the migrants to obtain more of their preferred foods such as fruits.<ref>{{cite journal |url=http://www.aliceboyle.net/My%20Articles/Boyle%20et%20al%202011_EvolEcol.pdf |title=Why do some, but not all, tropical birds migrate? A comparative study of diet breadth and fruit preference |author1=Boyle, W. A. |author2=Conway, C. J. |author3=Bronstein, J. L. |journal=Evolutionary Ecology |year=2011 |volume=25 |issue=1 |pages=219–236 |doi=10.1007/s10682-010-9403-4 |bibcode=2011EvEco..25..219B |s2cid=7516649}}</ref>

Altitudinal migration is common on mountains worldwide, such as in the [[Himalayas]] and the [[Andes]].<ref>{{cite web |url=http://www.groms.de/groms/work25/vortrag/KREFT.PDF |title=The Fourth Dimension: An Overview of Altitudinal Migration |publisher=25th Annual Bonn Convention, Berlin |date=23 June 2004 |access-date=27 March 2013 |author=Kreft, Stefan}}</ref> [[Dusky grouse]] in Colorado migrate less than a kilometer away from their summer grounds to winter sites which may be higher or lower by about 400 m in altitude than the summer sites.<ref>{{cite journal|author1=Cade, Brian S.|author2=Hoffman, Richard W.|year=1993|title=Differential Migration of Blue Grouse in Colorado|journal=The Auk|volume=110|issue=1|pages=70–77|doi=10.1093/auk/110.1.70|doi-broken-date=1 November 2024}}</ref>

Many bird species in arid regions across southern Australia are nomadic; they follow water and food supply around the country in an irregular pattern, unrelated to season but related to rainfall. Several years may pass between visits to an area by a particular species.<ref name="FindingOzBirds">{{Cite book |url=https://books.google.com/books?id=OquSAwAAQBAJ&q=nomadism+birds+australia&pg=PR14 |title=Finding Australian Birds : a Field Guide to Birding Locations. |last=Rohan. |first=Clarke |date=2014 |publisher=CSIRO Publishing |isbn=978-1-4863-0084-6 |oclc=880410149 |page=xiv}}</ref>