Editing Orca (section)

==Behaviour==
[[File:Orca 2.jpg|thumb|right|Orcas, like this one near Alaska, commonly [[Whale surfacing behaviour|breach]], often lifting their entire bodies out of the water.|alt=A killer whale leaping out of the water is about to land on its back.]]
Day-to-day orca behaviour generally consists of [[foraging]], travelling, resting and socializing. Orcas frequently engage in [[Whale surfacing behavior|surface behaviour]] such as breaching (jumping completely out of the water) and tail-slapping. These activities may have a variety of purposes, such as courtship, communication, dislodging [[parasite]]s, or [[Play (animal behavior)|play]]. [[Spyhopping]] is a behaviour in which a whale holds its head above water to view its surroundings.{{sfn|Carwardine|2001|p=64}} Resident orcas swim alongside [[porpoise]]s and other [[dolphin]]s.<ref name="OCR 11-2019">{{cite news |last=Connelly |first=Laylan |title=Videos show killer whales frantically hunting for dolphins off San Clemente |publisher=[[Orange County Register|The OCR]] |url=https://www.ocregister.com/2019/07/30/videos-show-killer-whales-in-a-frantic-hunt-for-dolphins-off-san-clemente/ |date=July 30, 2019 |access-date=November 24, 2019 |archive-date=December 10, 2019 |archive-url=https://web.archive.org/web/20191210204422/https://www.ocregister.com/2019/07/30/videos-show-killer-whales-in-a-frantic-hunt-for-dolphins-off-san-clemente/ |url-status=live }}</ref>

Orcas will engage in [[surplus killing]], that is, killing that is not designed to be for food. As an example, a BBC film crew witnessed orca in [[British Columbia]] playing with a male [[Steller sea lion]] to exhaustion, but not eating it.<ref>{{Cite web|url=https://www.youtube.com/watch?v=3f-FsAUcqMs|title=Orcas Kill, But Not Just for Food (2:06)|website=YouTube|date=April 19, 2022|language=en|access-date=2 June 2023|archive-date=June 2, 2023|archive-url=https://web.archive.org/web/20230602121314/https://www.youtube.com/watch?v=3f-FsAUcqMs|url-status=live}}</ref>

Some orcas have been observed swimming with dead [[Salmon hat|salmon on their heads]], resembling hats.<ref>{{cite web | title=Why orcas wear dead salmon as 'hats' remains a mystery, scientists say | website=CBC | date=November 30, 2024 | url=https://www.cbc.ca/news/canada/british-columbia/orca-dead-salmon-hat-1.7397920 | access-date=December 1, 2024}}</ref>

===Social structure===
Orcas have complex societies. Only [[elephant]]s and [[higher primate]]s live in comparably complex [[social structure]]s.{{sfn|Heimlich|Boran|2001|p=35}} Due to orcas' complex social bonds, many marine experts have concerns about how humane it is to keep [[Captive killer whales|them in captivity]].<ref>{{cite web |url=http://www.keepwhaleswild.org/ |title=Keep Whales Wild |publisher=Keep Whales Wild |date=January 14, 2011 |access-date=February 16, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20101216065407/http://www.keepwhaleswild.org/ |archive-date=December 16, 2010 }}</ref>

Resident orcas in the eastern North Pacific live in particularly complex and stable social groups. Unlike any other known mammal social structure, resident whales live with their mothers for their entire lives. These family groups are based on [[matriline]]s consisting of the eldest female (matriarch) and her sons and daughters, and the descendants of her daughters, etc. The average size of a matriline is 5.5 animals. Because females can reach age 90, as many as four generations travel together. These matrilineal groups are highly stable. Individuals separate for only a few hours at a time, to mate or forage. The permanent separation of an individual from a resident matriline has only been recorded once, in the case of an orca named [[Luna (orca)|Luna]].{{sfn|NMFS|2005|p=12}}

[[File:Transient Orcas (3727711709).jpg|thumb|A pair of orcas in the [[Pacific Northwest]]]]
Closely related matrilines form loose aggregations called pods, usually consisting of one to four matrilines. Unlike matrilines, pods may separate for weeks or months at a time.{{sfn|NMFS|2005|p=12}} [[DNA]] testing indicates resident males nearly always mate with females from other pods.{{sfn|NMFS|2005|p=39}} Clans, the next level of resident social structure, are composed of pods with similar dialects, and common but older maternal heritage. Clan ranges overlap, mingling pods from different clans.{{sfn|NMFS|2005|p=12}} The highest association layer is the community, which consists of pods that regularly associate with each other but share no maternal relations or dialects.<ref>{{cite book|last1=Ford|first1= J. K. B.|last2=Ellis|first2= G. M.|last3=Balcomb|first3= K. C.|year=1999|title=Killer Whales: The Natural History and Genealogy of ''Orcinus orca'' in British Columbia and Washington State|publisher=University of British Columbia Press|page=25|isbn=978-0774804691}}</ref>

Transient pods are smaller than resident pods, typically consisting of an adult female and one or two of her offspring. Males typically maintain stronger relationships with their mothers than other females. These bonds can extend well into adulthood. Unlike residents, extended or permanent separation of transient offspring from natal matrilines is common, with juveniles and adults of both sexes participating. Some males become "rovers" and do not form long-term associations, occasionally joining groups that contain reproductive females.{{sfn|NMFS|2005|p=13}} As in resident clans, transient community members share an acoustic repertoire, although regional differences in vocalizations have been noted.{{sfn|NMFS|2005|p=14}}

As with residents and transients, the lifestyle of these whales appears to reflect their diet; fish-eating orcas off Norway have resident-like social structures, while mammal-eating orcas in Argentina and the [[Crozet Islands]] behave more like transients.{{sfn|Ford|Ellis|Balcomb|2000|p=27}}

Orcas of the same sex and age group may engage in physical contact and synchronous surfacing. These behaviours do not occur randomly among individuals in a pod, providing evidence of "friendships".<ref>{{cite journal|author=Weiss|first1= M. N.|display-authors=etal|year=2021|title=Age and sex influence social interactions, but not associations, within a killer whale pod|journal=Proceedings of the Royal Society B: Biological Sciences|volume=288|issue=1953|doi=10.1098/rspb.2021.0617|pmid=34130498|pmc=8206696|hdl=10871/125706|hdl-access=free}}</ref><ref>{{cite journal|author=Lesté-Lasserre|first1=Christa|date=June 17, 2021|title=Killer whales form killer friendships, new drone footage suggests|journal=Science|url=https://www.science.org/content/article/killer-whales-form-killer-friendships-new-drone-footage-suggests|access-date=June 18, 2021|archive-date=December 5, 2022|archive-url=https://web.archive.org/web/20221205121706/https://www.science.org/content/article/killer-whales-form-killer-friendships-new-drone-footage-suggests|url-status=live}}</ref>

===Vocalizations===
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{{See also|Whale vocalization{{!}}Whale sound}}
Like all [[cetaceans]], orcas depend heavily on underwater sound for orientation, feeding, and communication. They produce three categories of sounds: clicks, whistles, and pulsed calls. Clicks are believed to be used primarily for navigation and discriminating prey and other objects in the surrounding environment, but are also commonly heard during social interactions.<ref name=noaa/>

Northeast Pacific resident groups tend to be much more vocal than transient groups in the same waters.{{sfn|NMFS|2005|p=20}} Residents feed primarily on [[Chinook salmon|Chinook]] and [[Chum salmon|chum]] salmon, which are insensitive to orca calls (inferred from the audiogram of Atlantic salmon). In contrast, the [[marine mammal]] prey of transients hear whale calls well and thus transients are typically silent.{{sfn|NMFS|2005|p=20}} Vocal behaviour in these whales is mainly limited to surfacing activities and milling (slow swimming with no apparent direction) after a kill.<ref>{{cite journal|last1=Deeck|first1= V. B.|last2=Ford|first2= J. K. B.|last3=Slater|first3= P. J. B.|year=2005|title=The vocal behaviour of mammal-eating killer whales: communicating with costly calls|journal=Animal Behaviour|volume=69|issue=2|pages=395–405|doi=10.1016/j.anbehav.2004.04.014|s2cid=16899659}}</ref>

All members of a resident pod use similar calls, known collectively as a [[dialect]]. Dialects are composed of specific numbers and types of discrete, repetitive calls. They are complex and stable over time.<ref>{{cite journal|author=Foote|first1= A. D.|last2=Osborne|first2= R. W.|last3=Hoelzel|first3= A.|year=2008|title=Temporal and contextual patterns of killer whale (''Orcinus orca'') call type production|journal=Ethology|volume=114|issue=6|pages=599–606|doi=10.1111/j.1439-0310.2008.01496.x|bibcode= 2008Ethol.114..599F}}</ref> Call patterns and structure are distinctive within matrilines.<ref name=vocal/> Newborns produce calls similar to their mothers, but have a more limited repertoire.{{sfn|NMFS|2005|p=14}} Individuals likely learn their dialect through contact with pod members.<ref>{{cite journal|last1=Filatova|first1= Olga A.|last2=Fedutin|first2= Ivan D.|last3=Burdin|first3= Alexandr M.|last4=Hoyt|first4= Erich|year=2007|url=http://russianorca.com/Doc/Science/structure_repert.pdf|title=The structure of the discrete call repertoire of killer whales ''Orcinus orca'' from Southeast Kamchatka|journal=Bioacoustics|volume=16|pages=261–280|doi=10.1080/09524622.2007.9753581|issue=3|bibcode= 2007Bioac..16..261F|s2cid=56304541|access-date=February 23, 2010|archive-date=July 15, 2011|archive-url=https://web.archive.org/web/20110715214729/http://russianorca.com/Doc/Science/structure_repert.pdf|url-status=live}}</ref> Family-specific calls have been observed more frequently in the days following a calf's birth, which may help the calf learn them.<ref>{{cite journal|url=http://www.coloradocollege.edu/dept/ev/Research/Faculty/OVALItems/pdf_Papers/SpongCalvesPaper.pdf |archive-url=https://web.archive.org/web/20110527060306/http://www.coloradocollege.edu/dept/ev/Research/Faculty/OVALItems/pdf_Papers/SpongCalvesPaper.pdf |archive-date=May 27, 2011 |last1=Weiß |first1=Brigitte M. |journal=The Journal of the Acoustical Society of America |volume=119 |last2=Ladich |issue=1 |first2=Friedrich |last3=Spong |first3=Paul |last4=Symonds |first4=Helena |year=2006 |pmid=16454316 |title=Vocal behaviour of resident killer whale matrilines with newborn calves: The role of family signatures |doi=10.1121/1.2130934 |pages=627–635 |bibcode=2006ASAJ..119..627W |url-status=dead }}</ref> Dialects are probably an important means of maintaining group identity and cohesiveness. Similarity in dialects likely reflects the degree of relatedness between pods, with variation growing over time.{{sfn|NMFS|2005|pp=15–16}} When pods meet, dominant call types decrease and subset call types increase. The use of both call types is called biphonation. The increased subset call types may be the distinguishing factor between pods and inter-pod relations.<ref name=vocal>{{cite journal|author=Kremers|first1= D.|last2=Lemasson|first2= A.|last3=Almunia|first3= J.|last4=Wanker|first4= R.|year=2012|title=Vocal sharing and individual acoustic distinctiveness within a group of captive orcas (''Orcinus orca'')|journal=Journal of Comparative Psychology|volume=126|issue=4|pages=433–445|doi=10.1037/a0028858|pmid=22866769}}</ref>

Dialects also distinguish types. Resident dialects contain seven to 17 (mean = 11) distinctive call types. All members of the North American west coast transient community express the same basic dialect, although minor regional variation in call types is evident. Preliminary research indicates offshore orcas have group-specific dialects unlike those of residents and transients.{{sfn|NMFS|2005|pp=15–16}}

Norwegian and Icelandic [[herring]]-eating orcas appear to have different vocalizations for activities like hunting.<ref>{{cite journal|author=Simon|first1= M.|last2=McGregor|first2= P. K.|last3=Ugarte|first3= F.|year=2007|title=The relationship between the acoustic behaviour and surface activity of killer whales (''Orcinus orca'') that feed on herring (''Clupea harengus'')|journal=Acta Ethologica|volume=10|issue=2|pages=47–53|doi=10.1007/s10211-007-0029-7|s2cid=29828311}}</ref> A population that live in [[McMurdo Sound]], [[Antarctica]] have 28 complex burst-pulse and whistle calls.<ref>{{Cite web|url=https://newatlas.com/science/smallest-killer-whale-large-musical-repertoire/|title=The smallest killer whale has a large musical repertoire|last=Szondy|first=David|date=February 26, 2020|website=New Atlas|language=en-US|url-status=live|access-date=February 27, 2020|archive-date=February 27, 2020|archive-url=https://web.archive.org/web/20200227234559/https://newatlas.com/science/smallest-killer-whale-large-musical-repertoire/}}</ref>

===Intelligence===
{{Main|Cetacean intelligence}}
Orcas have the second-heaviest brains among marine mammals<ref name=spear>{{cite news|last=Spear|first= Kevin|url=https://www.orlandosentinel.com/2010/03/06/killer-whales-how-smart-are-they/ |title=Killer whales: How smart are they?|archive-url=https://web.archive.org/web/20150908001401/http://articles.orlandosentinel.com/2010-03-06/news/os-seaworld-killer-whale-brains-20100302_1_killer-whales-orcas-dolphin-or-porpoise |archive-date=September 8, 2015 |work=Orlando Sentinel|date= March 7, 2010|url-status=live|access-date= March 7, 2010}}</ref> (after [[sperm whale]]s, which have the largest brain of any animal).<ref>{{Cite news|last=Dunham|first=Will|date=2017-10-16|title=Big and brilliant: complex whale behavior tied to brain size|language=en|work=Reuters|url=https://www.reuters.com/article/us-science-whales-idUSKBN1CL30I|access-date=2020-12-23|archive-date=July 19, 2021|archive-url=https://web.archive.org/web/20210719045118/https://www.reuters.com/article/us-science-whales-idUSKBN1CL30I|url-status=live}}</ref> Orcas have more [[grey matter|gray matter]] and more cortical neurons than any mammal, including humans.<ref>{{Cite journal |last1=Ridgway |first1=Sam H. |last2=Brownson |first2=Robert H. |last3=Van Alstyne |first3=Kaitlin R. |last4=Hauser |first4=Robert A. |date=2019-12-16 |editor-last=Li |editor-first=Songhai |title=Higher neuron densities in the cerebral cortex and larger cerebellums may limit dive times of delphinids compared to deep-diving toothed whales |journal=PLOS ONE |language=en |volume=14 |issue=12 |pages=e0226206 |doi=10.1371/journal.pone.0226206 |issn=1932-6203 |pmc=6914331 |pmid=31841529 |bibcode=2019PLoSO..1426206R |doi-access=free }}</ref> They can be [[Animal training|trained]] in captivity and are often described as intelligent,<ref name=cbs2010/>{{sfn|Carwardine|2001|p=67}} although defining and measuring "intelligence" is difficult in a species whose environment and behavioural strategies are very different from those of humans.{{sfn|Carwardine|2001|p=67}} Orcas imitate others, and seem to deliberately teach skills to their kin. Off the [[Crozet Islands]], mothers push their calves onto the beach, waiting to pull the youngster back if needed.{{sfn|Heimlich|Boran|2001|p=45}}{{sfn|Baird|2002|pp=61–62}} In March 2023, a female orca was spotted with a newborn [[pilot whale]] in [[Snæfellsnes]].<ref>{{cite news | url=https://www.theguardian.com/environment/2023/mar/10/killer-whale-orca-adopts-abducts-pilot-whale-calf-aoe | title='Extraordinary' sighting of orca with baby pilot whale astounds scientists | newspaper=The Guardian | date=March 10, 2023 | last1=Weston | first1=Phoebe }}</ref>

[[File:Orca with iceball cropped.JPG|thumb|An orca plays with a ball of ice, soon after a researcher threw a snowball at the whale.]]
People who have interacted closely with orcas offer numerous [[Anecdotal evidence|anecdotes]] demonstrating the whales' curiosity, playfulness, and ability to solve problems. Alaskan orcas have not only learned how to steal fish from [[Longline fishing|longlines]], but have also overcome a variety of techniques designed to stop them, such as the use of unbaited lines as decoys.{{sfn|Obee|Ellis|1992|p=42}} Once, fishermen placed their boats several miles apart, taking turns retrieving small amounts of their catch, in the hope that the whales would not have enough time to move between boats to steal the catch as it was being retrieved. The tactic worked initially, but the orcas adapted quickly and split into groups.{{sfn|Obee|Ellis|1992|p=42}}

In other anecdotes, researchers describe incidents in which wild orcas playfully tease humans by repeatedly moving objects the humans are trying to reach,<ref name=BF>{{Cite journal |year=2005 |title=Killer whale games |journal=Blackfish Sounder |volume=13 |page=5 |url=http://www.killerwhale.org/BFS/BFS_13.pdf |archive-url=https://web.archive.org/web/20071011062137/http://www.killerwhale.org/BFS/BFS_13.pdf |archive-date=October 11, 2007 |url-status=dead}}</ref> or suddenly start to toss around a chunk of ice after a human throws a snowball.<ref>Pitman, Robert L. [http://www.livescience.com/animals/090206-nhm-killer-whale-snowball.html Scientist Has 'Snowball Fight' With a Killer Whale] {{Webarchive|url=https://web.archive.org/web/20200915041640/https://www.livescience.com/3284-scientist-snowball-fight-killer-whale.html |date=September 15, 2020 }}. ''Live Science'', February 6, 2009. Retrieved March 7, 2010</ref>

The orca's use of dialects and the passing of other learned behaviours from generation to generation have been described as a form of [[animal culture]].<ref>{{Cite journal |doi=10.1371/journal.pbio.0050139 |last=Marino |first=Lori |title=Cetaceans Have Complex Brains for Complex Cognition |journal=[[PLOS Biology]] |year=2007 |page=e139 |volume=5 |issue=e139 |pmid=17503965 |pmc=1868071 |display-authors=etal |doi-access=free }}</ref>

{{blockquote|The complex and stable vocal and behavioural cultures of [[Sympatry|sympatric]] groups of killer whales (''Orcinus orca'') appear to have no parallel outside humans and represent an independent evolution of cultural faculties.<ref name=rendell>{{cite journal|last1=Rendell|first1= Luke|first2=Hal|last2= Whitehead|url=http://whitelab.biology.dal.ca/lr/bbs.htm|title=Culture in whales and dolphins|journal=Behavioral and Brain Sciences|year=2001|volume=24|issue=2|pages=309–324|access-date=March 7, 2010|pmid=11530544|doi=10.1017/S0140525X0100396X|s2cid=24052064|archive-date=May 30, 2010|archive-url=https://web.archive.org/web/20100530054246/http://whitelab.biology.dal.ca/lr/bbs.htm|url-status=live}}</ref>}}