Editing Songbird (section)

==Description==
The song in this clade is essentially territorial, because it communicates the identity and whereabouts of an individual to other birds, and also signals sexual intentions. Sexual selection among songbirds is highly based on mimetic vocalization. Female preference has shown in some populations to be based on the extent of a male's song repertoire. The larger a male's repertoire, the more females a male individual attracts.<ref name="ByersKroodsma2008">{{cite journal |doi=10.1016/j.anbehav.2008.10.003 |title=Female mate choice and songbird song repertoires |journal=Animal Behaviour |volume=77 |issue=1 |pages=13–22 |year=2009 |last1=Byers |first1=Bruce E |last2=Kroodsma |first2=Donald E |s2cid=53146576 }}</ref> It is not to be confused with bird calls that are used for alarms and contact and are especially important in birds that feed or migrate in flocks. While almost all living birds [[Bird vocalization|give calls]] of some sort, well-developed songs are only given by a few lineages outside the songbirds. And still, not all songbirds proffer a call that is distinctly melodious. Songbirds do, however, possess a highly developed vocal organ, the [[Syrinx (bird anatomy)|syrinx]], that enables their sonorous activity. This organ, also known as a song box, can be found where the windpipe meets diverging bronchial tubes which lead to the lungs. The organ is a solid, bony structure lined with a film of membranes which air passes through as the songbird calls. While the song boxes of songbirds vary in size and intricacy, this does not necessarily determine the songbird's ability to voice their song. Researchers believe this has more to do with the length of the windpipe.<ref>{{Cite web|title=Songbird {{!}} bird|url=https://www.britannica.com/animal/songbird|access-date=2020-12-02|website=Encyclopedia Britannica|language=en}}</ref> 
[[File:Turdus-migratorius-003.ogg|left|thumb|The [[American robin]], like most thrushes, has a complex near continuous song, consisting of discrete units often repeated and spliced by a string of pauses.]]
Other birds (especially non-passeriforms) sometimes have [[Bird vocalization|songs]] to attract mates or hold territory, but these are usually simple and repetitive, lacking the variety of many oscine songs. The monotonous repetition of the [[common cuckoo]] or [[little crake]] can be contrasted with the variety of a [[nightingale]] or [[marsh warbler]]. However, although many songbirds have songs that are pleasant to the human ear, this is not invariably the case. Many members of the [[Corvus (genus)|crow]] family ([[Corvidae]]) communicate with croaks or screeches, which sound harsh to humans. Even these, however, have a song of sorts, a softer twitter that is given between courting partners. And even though some [[parrot]]s (which are not songbirds) can be taught to repeat human speech, [[Bird vocalization|vocal mimicry]] among birds is almost completely restricted to songbirds, some of which (such as the [[lyrebird]]s or the aptly named [[mockingbird]]s) excel in imitating the sounds of other birds or even environmental noises.<ref>{{cite web |last1=Fleming |first1=Kaitlin |title=The Northern Mockingbird: Nature's Copycat |url=https://fsuornithology.wordpress.com/2011/12/11/the-northern-mockingbird-natures-copycat/ |website=FSU ornithology: the bird blogs |date=11 December 2011 |access-date=18 June 2018}}</ref>

The birds from higher altitudes have evolved thicker downs (also known as jackets) to protect themselves from colder temperatures. Their feathers have outer and inner portions, with the lower down being fluffier and warmer to provide increased warmth.<ref>{{Cite journal|last1=Barve|first1=Sahas|last2=Ramesh|first2=Vijay|last3=Dotterer|first3=Toni M.|last4=Dove|first4=Carla J.|title=Elevation and body size drive convergent variation in thermo-insulative feather structure of Himalayan birds|journal=Ecography|year=2021|volume=44|issue=5|pages=680–689|language=en|doi=10.1111/ecog.05376|issn=1600-0587|doi-access=free|bibcode=2021Ecogr..44..680B }}</ref>