Editing Bird (section)

== Threats and conservation ==
{{Main|Bird conservation}}
{{See also|Late Quaternary prehistoric birds|List of extinct birds|Raptor conservation}}
[[File:California-Condor3-Szmurlo edit.jpg|thumb|right|upright|alt=Large black bird with featherless head and hooked bill|The [[California condor]] once numbered only 22 birds, but conservation measures have raised that to over 500 today.]]

Human activities have caused population decreases or [[extinction]] in many bird species. Over a hundred bird species have gone extinct in historical times,<ref>{{cite book |last1=Fuller |first1=Errol |year=2000 |title=Extinct Birds |edition=2nd |publisher=[[Oxford University Press]] |location=Oxford & New York |isbn=0-19-850837-9}}</ref> although the most dramatic human-caused avian extinctions, eradicating an estimated 750–1800 species, occurred during the human colonisation of [[Melanesia]]n, [[Polynesia]]n, and [[Micronesia]]n islands.<ref>{{cite book |last1=Steadman |first1=D. |year=2006 |title=Extinction and Biogeography in Tropical Pacific Birds |publisher=University of Chicago Press |isbn=978-0-226-77142-7}}</ref> Many bird populations are declining worldwide, with 1,227 species listed as [[threatened species|threatened]] by [[BirdLife International]] and the [[IUCN]] in 2009.<ref>{{cite news |title=BirdLife International announces more Critically Endangered birds than ever before |work=BirdLife |publisher=[[BirdLife International]] |date=14 May 2009 |url=http://www.birdlife.org/news/pr/2009/05/red_list.html |access-date=15 May 2009 |archive-date=17 June 2013 |archive-url=https://web.archive.org/web/20130617183344/http://www.birdlife.org/news/pr/2009/05/red_list.html }}</ref><ref>{{cite news|url=http://news.bbc.co.uk/2/hi/science/nature/8045971.stm |first=Mark |last=Kinver |title=Birds at risk reach record high |work=BBC News Online |date=13 May 2009 |access-date=15 May 2009}}</ref> There have been long-term declines in North American bird populations, with an estimated loss of 2.9 billion breeding adults, about 30% of the total, since 1970.<ref>{{cite web |title=Nearly 3 Billion Birds Gone |url=https://www.birds.cornell.edu/home/bring-birds-back/ |website=CornellLab |access-date=5 May 2024}}</ref><ref>{{cite web |title=Vanishing: More Than 1 in 4 Birds Has Disappeared in the Last 50 Years
|first=Gustave |last=Axelson |date=19 September 2019 |url=https://www.allaboutbirds.org/news/vanishing-1-in-4-birds-gone/ |website=All About Birds |access-date=5 May 2024}}</ref>

The most commonly cited human threat to birds is [[Habitat destruction|habitat loss]].<ref>{{cite book |editor-last1=Norris |editor-first1=K |editor-last2=Pain |editor-first2=D |year=2002 |title=Conserving Bird Biodiversity: General Principles and their Application |publisher=Cambridge University Press |isbn=978-0-521-78949-3}}</ref> Other threats include overhunting, accidental mortality due to collisions with [[bird-skyscraper collisions|buildings]] or [[bird strike|vehicles]], [[long-line fishing]] [[bycatch]],<ref>{{Cite journal | doi=10.1016/0006-3207(91)90031-4 | last1=Brothers | first1=N. P. | year=1991 | title=Albatross mortality and associated bait loss in the Japanese longline fishery in the southern ocean | journal=Biological Conservation | volume=55 | issue=3| pages=255–268 | bibcode=1991BCons..55..255B }}</ref> pollution (including [[oil spill]]s and pesticide use),<ref>{{cite journal | last1=Wurster | first1=D. | last2=Wurster | first2=C. |author-link2=Charles Frederick Wurster| last3=Strickland | first3=W. | date=July 1965 | title=Bird Mortality Following DDT Spray for Dutch Elm Disease | journal=Ecology | volume=46 | issue=4| pages=488–499 | doi =10.2307/1934880 | jstor=1934880 | bibcode=1965Ecol...46..488W }}; {{cite journal | doi=10.1126/science.148.3666.90 | title=Bird Mortality after Spraying for Dutch Elm Disease with DDT | year=1965 | last1=Wurster | first1=C.F. | last2=Wurster | first2=D.H. | last3=Strickland | first3=W.N. | journal=Science | volume=148 | issue=3666 | pages=90–91 | pmid=14258730 | bibcode=1965Sci...148...90W }}</ref> competition and predation from nonnative [[invasive species]],<ref>{{cite journal | last1=Blackburn | first1=T. | last2=Cassey | first2=P. | last3=Duncan | first3=R. | last4=Evans | first4=K. | last5=Gaston | first5=K. | date=24 September 2004 | title=Avian Extinction and Mammalian Introductions on Oceanic Islands | journal=[[Science (journal)|Science]] | volume=305 | issue=5692| pages=1955–1958 | doi=10.1126/science.1101617 | pmid=15448269| bibcode=2004Sci...305.1955B }}</ref> and [[Climate change and birds|climate change]].

Governments and [[conservation biology|conservation]] groups work to protect birds, either by passing laws that [[In-situ conservation|preserve]] and [[ecological restoration|restore]] bird habitat or by establishing [[Ex-situ conservation|captive populations]] for reintroductions. Such projects have produced some successes; one study estimated that conservation efforts saved 16 species of bird that would otherwise have gone extinct between 1994 and 2004, including the [[California condor]] and [[Norfolk parakeet]].<ref>{{cite journal | doi=10.1017/S0030605306000950 | last1=Butchart | first1=S. | last2=Stattersfield | first2=A. | last3=Collar | first3=N | year=2006 | title=How many bird extinctions have we prevented? | journal=Oryx | volume=40 | issue=3 | pages=266–79 | doi-access=free }}</ref>

Human activities have allowed the expansion of a few temperate area species, such as the [[barn swallow]] and [[European starling]]. In the tropics and sub-tropics, relatively more species are expanding due to human activities, particularly due to the spread of crops such as rice whose expansion in south Asia has benefitted at least 64 bird species, though may have harmed many more species.<ref>{{Cite journal |last1=Sundar |first1=K. S. Gopi |last2=Subramanya |first2=S. |date=2010 |title=Bird use of rice fields in the Indian subcontinent |journal=Waterbirds |volume=33 |issue=Special Issue 1 |pages=44–70 |doi=10.1675/063.033.s104 }}</ref>