What is Bird sound?
[[File:Blackbird, singing.JPG|thumb|right|Male [[blackbird]] singing.]] '''Bird sounds''' include bird songs, calls and any other noises they make for [[communication]]. Birds do a lot of communicating, mostly to other birds of the same species. == Bird song == Bird songs are for other members of the same [[species]]. The functions are partnership, [[wikt:mating|mating]] and [[territory]] ownership. According to one expert source, the primary function is as a keep-off signal to other males of the same species.<ref>Attenborough's Wonder of Song. BBC tv. [https://www.bbc.co.uk/iplayer/episode/m00134jr/attenboroughs-wonder-of-song]</ref> Depending on the species, bird songs may differ for different [[functions]]. In general, bird songs are only used by [[Passeriformes]], the [[songbird]]s. It is one of their typical [[adaptations]]. Bird song may have evolved through [[sexual selection]]. Experiments suggest the quality of bird song may be a good indicator of [[fitness]].<ref>{{cite journal|author=Read A.W. and D.M. Weary|year=1990|title=Sexual selection and the evolution of bird song: a test of the Hamilton-Zuk hypothesis|journal=Behavioral Ecology and Sociobiology|volume=26|issue=1|pages=47–56|url=https://dx.doi.org/10.1007/BF00174024|doi=10.1007/BF00174024|s2cid=25177326|access-date=2014-10-19|archive-date=2019-09-24|archive-url=https://web.archive.org/web/20190924155251/https://link.springer.com/article/10.1007/BF00174024|url-status=dead}}</ref> Experiments also suggest that [[parasites]] and diseases may directly affect song characteristics such as song rate. This also acts as a reliable indicator of health.<ref>{{cite journal|author=Garamszegi L.Z. |display-authors = etal |year= 2004|title=Immune challenge mediates vocal communication in a passerine bird: an experiment|journal=Behavioral Ecology|volume=15|issue=1|pages= 148–157|doi=10.1093/beheco/arg108}}</ref><ref>{{cite journal|author=Redpath S.M. |display-authors = etal |year= 2000|title=Do male hoots betray parasite loads in tawny owls?|journal=Journal