Editing Orca (section)

==Life cycle==
[[File:091201 south georgia orca 5227 (4173390858).jpg|thumb|Adult female orca with calf near [[South Georgia and the South Sandwich Islands|South Georgia]]]]
Female orcas begin to mature at around the age of 10–13 and reach peak fertility around 20,<ref>{{cite web |title=Postreproductive female killer whales reduce socially inflicted injuries in their male offspring|url=https://www.sciencedirect.com/science/article/pii/S0960982223008242|date=7 August 2023|access-date=20 February 2025}}</ref><ref name=Reproduction>{{cite journal |last1=Ward |first1=Eric J. |last2=Holmes |first2=Elizabeth E. |last3=Balcomb |first3=Ken C. |title=Quantifying the effects of prey abundance on killer whale reproduction |journal=Journal of Applied Ecology |date=June 2009 |volume=46 |issue=3 |pages=632–640 |doi=10.1111/j.1365-2664.2009.01647.x|doi-access=free |bibcode=2009JApEc..46..632W }}</ref> experiencing periods of [[polyestrous]] cycling separated by non-cycling periods of three to 16 months. Females can often breed until age 40, followed by a rapid decrease in fertility.<ref name=Reproduction /> Orcas are among the few [[Menopause#Other animals|animals that undergo menopause]] and live for decades after they have finished breeding.<ref>{{cite journal |last1=Bowden |first1=D. M. |last2=Williams |first2=D. D. |title=Aging |journal=Advances in Veterinary Science and Comparative Medicine |date=1984 |volume=28 |pages=305–341 |pmid=6395674 |doi=10.1016/B978-0-12-039228-5.50015-2 |isbn=9780120392285}}</ref><ref>{{cite book|title=Physiological Basis of Aging and Geriatrics|edition= Fourth|first1=Paola S.|last1= Timiras|publisher= CRC Press|date= 2013| page= 161}}</ref> The lifespans of wild females average 50 to 80 years.<ref name="nationalgeographic.com">{{cite web |title=Orcas don't do well in captivity. Here's why. |url=https://www.nationalgeographic.com/animals/2019/03/orcas-captivity-welfare/ |website=Animals |access-date=31 May 2020 |language=en |date=25 March 2019 |archive-date=June 6, 2020 |archive-url=https://web.archive.org/web/20200606082028/https://www.nationalgeographic.com/animals/2019/03/orcas-captivity-welfare/ |url-status=dead }}</ref> Some are claimed to have lived substantially longer: [[Granny (orca)|Granny (J2)]] was estimated by some researchers to have been as old as 105 years at the time of her death, though a biopsy sample indicated her age as 65 to 80 years.{{sfn|Carwardine|2001|p=26}}<ref name=King>{{Cite news|url=http://www.king5.com/news/local/oldest-southern-resident-killer-whale-considered-dead/381349614|title=Oldest Southern Resident killer whale considered dead|last=TEGNA|newspaper=KING|language=en-US|access-date=January 3, 2017|archive-date=January 3, 2017|archive-url=https://web.archive.org/web/20170103094218/http://www.king5.com/news/local/oldest-southern-resident-killer-whale-considered-dead/381349614|url-status=live}}</ref><ref name="Orcazine">{{cite web|url=http://orcazine.com/granny-j2/|title=Orca Granny: was she really 105?|last=Podt|first=Annemieke|language=en-US|access-date=September 11, 2017|date=December 31, 2016|archive-date=October 15, 2018|archive-url=https://web.archive.org/web/20181015152227/http://orcazine.com/granny-j2/|url-status=live}}</ref> It is thought that orcas held in captivity tend to have shorter lives than those in the wild, although this is subject to scientific debate.<ref name="nationalgeographic.com"/><ref name=robeck>{{cite journal |last1=Robeck |first1=Todd R. |last2=Willis |first2=Kevin |last3=Scarpuzzi |first3=Michael R. |last4=O'Brien |first4=Justine K. |title=Comparisons of life-history parameters between free-ranging and captive killer whale (''Orcinus orca'') populations for application toward species management |url=https://academic.oup.com/jmammal/article/96/5/1055/920547|journal=Journal of Mammalogy |pages=1055–1070 |language=en |doi=10.1093/jmammal/gyv113 |date=29 September 2015 |volume=96 |issue=5 |pmid=26937049 |pmc=4668992 |archive-date=April 23, 2019 |archive-url=https://web.archive.org/web/20190423085700/https://academic.oup.com/jmammal/article/96/5/1055/920547 |url-status=dead }}</ref><ref>{{cite journal |last1=Jett |first1=John |last2=Ventre |first2=Jeffrey |title=Captive killer whale (''Orcinus orca'') survival |journal=Marine Mammal Science |pages=1362–1377 |language=en |doi=10.1111/mms.12225 |date=2015 |volume=31|issue=4 |bibcode=2015MMamS..31.1362J }}</ref>

Males mate with females from other pods, which prevents [[inbreeding]]. [[Gestation period|Gestation]] varies from 15 to 18 months.{{sfn|NMFS|2005|p=33}} Mothers usually calve a single offspring about once every five years. In resident pods, births occur at any time of year, although winter is the most common. Mortality is extremely high during the first seven months of life, when 37–50% of all calves die.{{sfn|NMFS|2005|p=35}} [[Weaning]] begins at about 12 months of age, and is complete by two years. According to observations in several regions, all male and female pod members participate in the care of the young.{{sfn|Heimlich|Boran|2001|p=35}}

Males sexually mature at the age of 15, but do not typically reproduce until age 21. Wild males live around 29 years on average, with a maximum of about 60 years.{{sfn|Carwardine|2001|p=26}} One male, known as [[Old Tom (killer whale)|Old Tom]], was reportedly spotted every winter between the 1840s and 1930 off [[New South Wales]], Australia, which would have made him up to 90 years old. Examination of his teeth indicated he died around age 35,<ref>Mitchell, E. and Baker, A. N. (1980). Age of reputedly old Killer Whale, ''Orcinus orca'', 'Old Tom' from Eden, Twofold Bay, Australia, in: W. F. Perrin and A. C. Myrick Jr (eds.): Age determination of toothed whales and sirenians, pp. 143–154 Rep. Int. Whal. Comm. (Special Issue 3), cited in [https://web.archive.org/web/20061014152551/http://www.t-d-e.org/knowkillerwhale.php Know the Killer Whale], The Dolphin's Encyclopaedia. Retrieved January 27, 2010</ref> but this method of age determination is now believed to be inaccurate for older animals.<ref>Olesiuk, Peter F.; Ellis, Graeme M. and Ford, John K. B. (2005). [http://www.pac.dfo-mpo.gc.ca/science/species-especes/cetacean-cetaces/CRP-publications/Olesiuk%20et%20al.%202005%20KW%20Pop%20Dyn.pdf Life History and Population Dynamics of Northern Resident Killer Whales (''Orcinus orca'') in British Columbia] {{webarchive|url=https://web.archive.org/web/20110419074348/http://www.pac.dfo-mpo.gc.ca/science/species-especes/cetacean-cetaces/CRP-publications/Olesiuk%20et%20al.%202005%20KW%20Pop%20Dyn.pdf |date=April 19, 2011 }}, Research Document 2005/045, Canadian Science Advisory Secretariat, Fisheries and Oceans Canada. p. 33. Retrieved January 27, 2010</ref> One male known to researchers in the [[Pacific Northwest]] (identified as J1) was estimated to have been 59 years old when he died in 2010.<ref>[http://www.whaleresearch.com/orca_ID.html How Southern Resident Killer Whales are Identified] {{webarchive|url=https://web.archive.org/web/20091128230801/http://www.whaleresearch.com/orca_ID.html |date=November 28, 2009 }}, Center for Whale Research. Retrieved March 23, 2012</ref> Orcas are unique among cetaceans, as their caudal sections elongate with age, making their heads relatively shorter.{{sfn|Heptner|Nasimovich|Bannikov|Hoffmann|1996|p=681}}

[[Infanticide (zoology)|Infanticide]], once thought to occur only in captive orcas, was observed in wild populations by researchers off British Columbia on December 2, 2016. In this incident, an adult male killed the calf of a female within the same pod, with the adult male's mother also joining in the assault. It is theorized that the male killed the young calf in order to mate with its mother (something that [[Infanticide in carnivores|occurs in other carnivore species]]), while the male's mother supported the breeding opportunity for her son. The attack ended when the calf's mother struck and injured the attacking male. Such behaviour matches that of many smaller dolphin species, such as the [[bottlenose dolphin]].<ref>{{Cite web | url=http://www.cbc.ca/news/canada/british-columbia/killer-whale-infanticide-1.4586867 | title='Horrified' scientists first to see killer whale infanticide &#124; CBC News | access-date=March 22, 2018 | archive-date=March 23, 2018 | archive-url=https://web.archive.org/web/20180323025412/http://www.cbc.ca/news/canada/british-columbia/killer-whale-infanticide-1.4586867 | url-status=live }}</ref>