Editing California sea lion

{{Short description|Species of carnivore}}
{{Good article}}
{{Speciesbox
| fossil_range = [[Pleistocene]]– Recent<ref>{{Cite web|url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=96087|title=Fossilworks: Zalophus californianus|access-date=2022-01-26|archive-date=2023-03-29|archive-url=https://web.archive.org/web/20230329070358/http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=96087|url-status=live}}</ref>
| image = Sea Lions At La Jolla Cove - 32.jpg
| image_caption = Male
| image2 = California sea lion in La Jolla (70568).jpg
| image2_caption = Female<br />Both in [[La Jolla, California]]
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 11 November 2021">{{cite iucn |author=Aurioles-Gamboa, D. |author2=Hernández-Camacho, J. |date=2015 |title=''Zalophus californianus'' |volume=2015 |page=e.T41666A45230310 |doi=10.2305/IUCN.UK.2015-4.RLTS.T41666A45230310.en |access-date=11 November 2021}}</ref>
| genus = Zalophus
| species = californianus
| authority = ([[René-Primevère Lesson|Lesson]], 1828)
| range_map = Zalophus californianus distribution.png
| range_map_caption = 
{{align|left|{{color box|#3B1BC6}} breeding range}}<br />
{{align|left|{{color box|#53A8DE}} total range}}
}}

The '''California sea lion''' ('''''Zalophus californianus''''') is a coastal [[eared seal]] native to western [[North America]]. It is one of six species of [[sea lion]]s. Its natural habitat ranges from [[southeast Alaska]] to central [[Mexico]], including the [[Gulf of California]]. California sea lions are [[Sexual dimorphism|sexually dimorphic]]; males are larger than females, and have a thicker neck, and a protruding [[sagittal crest]]. They mainly [[Hauling-out|haul out]] on sandy or rocky beaches, but they also frequent manmade environments such as [[marina]]s and [[Wharf|wharves]]. California sea lions feed on a number of species of fish and squid, and are preyed on by [[orca]]s and [[great white shark]]s.

California sea lions have a [[Polygyny in animals|polygynous]] breeding pattern. From May to August, males establish [[territory (animal)|territories]] and try to attract females with which to mate. Females are free to move in between territories, and are not coerced by males. Mothers nurse their pups in between foraging trips. California sea lions communicate with numerous vocalizations, notably with [[Bark (sound)|barks]] and mother-pup [[contact call]]s. Outside their breeding season, California sea lions spend much of their time at sea, but they come to shore to [[Moulting|molt]].

California sea lions are particularly [[Animal cognition|intelligent]], can be trained to perform various tasks and display limited fear of humans if accustomed to them. Because of this, California sea lions are a popular choice for public display in [[zoo]]s, [[circus]]es and [[oceanarium]]s, and are [[United States Navy Marine Mammal Program|trained by the United States Navy for certain military operations]]. The [[International Union for Conservation of Nature]] (IUCN) lists the species as [[Least Concern]] due to its abundance.  To protect fish, the US states of [[Oregon]] and [[Washington (state)|Washington]] engage in annual kill quotas of California sea lions.

==Taxonomy==
[[File:Zalophus californianus J. Smit.jpg|thumb|left|Lithography by [[Joseph Smit]].]]
The California sea lion was [[Species description|described]] by [[René Primevère Lesson]], a French naturalist, in 1828. It is grouped with other sea lions and [[fur seal]]s in the family [[Otariidae]]. Otariids, also known as eared seals, differ from [[true seals]] in having external ear flaps, and proportionately larger foreflippers and pectoral muscles. Along with the [[Galapagos sea lion]] and the extinct [[Japanese sea lion]], the California sea lion belongs to the genus ''[[Zalophus]]'', which derives from the Greek words ''za'', meaning "intensive", and ''lophus,'' meaning "crest".<ref>{{cite book |last1=Allen |first1=Sarah G. |last2=Mortenson |first2=Joe |last3=Webb |first3=Sophie |year=2011 |title=Field Guide to Marine Mammals of the Pacific Coast: Baja, California, Oregon, Washington, British Columbia |publisher=[[University of California Press]] |page=403 |isbn=978-0520265455}}</ref> This refers to the protruding [[sagittal crest]] of the males, which distinguishes members of the genus.<ref name=Perrin>{{cite book |last1=Heath |first1=Carolyn B. |last2=Perrin |first2=William F. |year=2008 |contribution=California, Galapagos and Japanese Sea Lions ''Zalophus californianus'', ''Z. wollebaeki'' and ''Z. japonicus'' |pages=[https://archive.org/details/encyclopediamari00perr/page/n204 170]–75 |title=Encyclopedia of Marine Mammals |publisher=Elsevier Science |url=https://archive.org/details/encyclopediamari00perr |url-access=limited |editor1-last=Perrin |editor1-first=William F. |editor2-last=Würsig |editor2-first=Bernd |editor3-last=Thewissen |editor3-first=J.G.M. |edition=2nd |isbn=978-0123735539}}</ref>

Traditionally, the Galapagos sea lion and Japanese sea lion were classified as [[subspecies]] of the California sea lion. However, a genetic study in 2007 found that all three are in fact separate species.<ref>{{cite journal |last1=Wolf |first1=Jochen B.W. |last2=Tautz |first2=Diethard |last3=Trillmich |first3=Fritz |year=2007 |title= Galápagos and Californian sea lions are separate species: Genetic analysis of the genus ''Zalophus'' and its implications for conservation management |journal=[[Frontiers in Zoology]] |volume=4 |page=20 |doi=10.1186/1742-9994-4-20 |pmid=17868473 |pmc=2072946 |doi-access=free }}</ref> The [[Lineage (evolution)|lineages]] of the California and Japanese sea lion appear to have [[Genetic divergence|split off]] 2.2 million years ago during the [[Pliocene]].<ref>{{cite journal |last1=Sakahira |first1=F. |last2=Niimi |first2=M. |year=2007 |title=Ancient DNA analysis of the Japanese sea lion (''Zalophus californianus japonicus'' Peters, 1866): preliminary results using mitochondrial control-region sequences |journal=[[Zoological Science]] |volume=24 |issue=1 |pages=81–85 |pmid=17409720 |doi=10.2108/zsj.24.81|s2cid=10824601 }}</ref> The California sea lion differs from the Galapagos sea lion in its greater [[sexual dimorphism]].<ref name=Perrin/> The [[Steller sea lion]] is the closest extant relative of the ''Zalophus'' sea lions, being a [[sister taxon]].<ref name=populations/>

==Appearance, physiology, and movement==
[[File:Zalophus californianus 01.JPG|thumb|left|California sea lion skeleton]]

Being sexually dimorphic, California sea lions differ in size, shape, and coloration between the sexes. Males can grow up to {{convert|2.5|-|2.7|m|ft|abbr=on}} long and weigh around {{convert|350|kg|lb|abbr=on}}, while females are typically around {{convert|2.1|m|ft|abbr=on}} and weigh around {{convert|100|kg|lb|abbr=on}}.<ref name=Perrin/> The heaviest recorded male weighed {{Cvt|660|kg|lb}}.<ref>{{cite book |last1=Stapp |first1=Darby C. |title=Journal of Northwest Anthropology: Volume 49 Number 2 |date=1 September 2015 |publisher=Northwest Anthropology |isbn=978-1-5174-9639-5 |pages=193 |url=https://books.google.com/books?id=tJlWDwAAQBAJ |language=en}}</ref> Females and juveniles have a tawny brown [[Coat (animal)|pelage]],<ref name=Perrin/> although they may be temporarily light gray or silver after [[Moulting|molting]].<ref name=Audubon/> The pelage of adult males can be anywhere from light brown to black, but is typically dark brown.<ref name=Perrin/> The face of adult males may also be light tan in some areas. Pups have a black or dark brown pelage at birth.<ref name=Audubon/> Although the species has a slender build, adult males have robust necks, chests, and shoulders.<ref name=Audubon>{{cite book |last1=Reeves |first1=Randall R. |last2=Stewart |first2=Brent S. |last3=Clapham |first3=Phillip J. |last4=Powell |first4=James A. |year=2002 |title=National Audubon Society Guide to Marine Mammals of the World |publisher=Alfred A. Knopf |pages=[https://archive.org/details/guidetomarinemam00folk/page/90 90–93] |isbn=978-0375411410 |url-access=registration |url=https://archive.org/details/guidetomarinemam00folk/page/90 }}</ref> Adult males also have a protruding crest which gives them a "high, domed forehead";<ref name=eared/> it is tufted with white hairs.<ref name=Perrin/> They also have manes, which are less developed than those of adult male [[South American sea lion|South American]] and Steller sea lions.<ref name=eared>{{cite book |last1=Lavigne |first1=David M. |last2=Harwood |first2=John |year=2001 |contribution=Eared seal species |title=The Encyclopedia of Mammals |editor-first=MacDonald |editor-last=David |publisher=[[Oxford University Press]] |page=171 |edition=2nd |isbn=978-0760719695}}</ref> Both sexes have long, narrow muzzles.<ref name=Audubon/>

As an otariid, the California sea lion relies on its foreflippers to propel itself when swimming. This form of [[aquatic locomotion]], along with its streamlined body, effectively reduces [[Drag (physics)|drag]] underwater. Its foreflipper movement is not continuous; the animal glides in between each stroke.<ref name=Feldkamp>{{cite journal |last=Feldkamp |first=S.D. |year=1987 |title=Swimming in the California sea lion: morphometrics, drag and energetics |journal=[[The Journal of Experimental Biology]] |volume=131 |pages=117–135 |pmid=3694112 |url=http://jeb.biologists.org/content/131/1/117.full.pdf |issue=1|doi=10.1242/jeb.131.1.117|doi-access=free }}</ref> The flexibility of its spine allows the California sea lion to bend its neck backwards far enough to reach its hindflippers. This allows the animal to make dorsal turns and maintain a streamlined posture.<ref>{{cite journal |last1=Fish |first1=Frank E. |last2=Hurley |first2=Jenifer |last3=Costa |first3=Daniel P. |year=2003 |title=Maneuverability by the sea lion ''Zalophus californianus'': turning performance of an unstable body design |journal=[[The Journal of Experimental Biology]] |volume=206 |pages=667–674 |doi=10.1242/jeb.00144 |url=http://jeb.biologists.org/content/206/4/667.full.pdf |pmid=12517984 |issue=Pt 4|s2cid=12066187|doi-access=free}}</ref> When moving on land, the California sea lion is able to turn its hindflippers forward and walk on all fours. It moves the foreflippers in a [[Transverse plane|transverse]], rather than a [[Sagittal plane|sagittal]], fashion. In addition, it relies on movements of its head and neck more than its hindflippers for terrestrial locomotion.<ref>{{cite journal |last=English |first=Arthur Wm. |year=1976 |title=Limb movements and locomotor function in the California sea lion (''Zalophus californianus'') |journal=[[Journal of Zoology]] |volume=178 |issue=3 |pages=341–364 |doi= 10.1111/j.1469-7998.1976.tb02274.x}}</ref> California sea lions may travel at speeds of around {{convert|10.8|km/h|mph|abbr=on}},<ref name=Lowry/> and can dive at depths of {{convert|274|m|ft|abbr=on}} and for up to 9.9 minutes, though most dives are typically {{convert|80|m|ft|abbr=on}} and last less than 3 minutes.<ref>{{cite journal |last1=Feldkamp |first1=Steven D. |last2=DeLong |first2=Robert L. |last3=Antonelis |first3=George A. |year=1989 |title=Diving patterns of California sea lions, ''Zalophus californianus'' |journal=[[Canadian Journal of Zoology]] |volume=67 |issue=4 |pages=872–883 |doi=10.1139/z89-129|url=https://zenodo.org/record/1235911 }}</ref>

[[File:Lion de mer Amnéville 01.jpg|thumb|right|California sea lion swimming underwater]]
California sea lions have [[color vision]], though it is limited to the blue-green area of the [[Visible spectrum|color spectrum]]. This is likely an adaptation for living in marine coastal habitats.<ref>{{cite journal |last1=Griebel |first1=U. |last2=Schmid |first2=A. |year=1992 |title=Color vision in the California sea lion (''Zalophus californianus'') |journal=[[Vision Research]] |volume=32 |issue=3 |pages=477–482 |pmid=1604834 |doi=10.1016/0042-6989(92)90239-F|s2cid=40123080 }}</ref> Sea lions have fairly acute underwater hearing, with a hearing range of 0.4–32 [[hertz|kHz]].<ref>{{cite journal |last1=Reichmuth |first1=Colleen |last2=Southall |first2=Brandon L. |year=2012 |title=Underwater hearing in California sea lions (Zalophus californianus): Expansion and interpretation of existing data |journal=Marine Mammal Science |volume=28 |issue=2 |pages=358–363 |doi=10.1111/j.1748-7692.2011.00473.x |bibcode=2012MMamS..28..358R |url=http://pinnipedlab.ucsc.edu/publications/pub_146_2011.pdf |access-date=2012-06-08 |archive-url=https://web.archive.org/web/20130513041331/http://pinnipedlab.ucsc.edu/publications/pub_146_2011.pdf |archive-date=2013-05-13 |url-status=dead }}</ref> California sea lions rely on their [[whiskers]] or vibrissae for touch and detection of vibrations underwater. Compared to the [[harbor seal]], the California sea lion's vibrissae are smoother and less specialized and thus perform less when following hydrodynamic trails, although they still perform well.<ref>{{cite journal|author=Gläser, N.|year=2011|title=Hydrodynamic trail following in a California sea lion (''Zalophus californianus'')|journal=Journal of Comparative Physiology A|volume=197|issue=2|pages=141–51|pmid=20959994|doi=10.1007/s00359-010-0594-5|s2cid=22267851|display-authors=etal}}</ref>

==Ecology==
===Range and habitat===
[[File:Santa-Barbara-Island-Sea-Lion-Rookery.jpg|thumb|left|California sea lion rookery on Santa Barbara island]]
The California sea lion ranges along the western coast and islands of [[North America]], from [[southeast Alaska]] to central [[Mexico]]. [[Mitochondrial DNA]] sequences in 2009 have identified five distinct California sea lion populations: the U.S. or Pacific Temperate stock, the Western [[Baja California Peninsula|Baja California]] or Pacific Tropical stock, and the Southern, Central, and Northern [[Gulf of California]] stocks.<ref name=populations>{{cite journal |last1=Schramm |first1=Yolanda |last2=Mesnick |first2=S. L. |last3=de la Rosa |first3=J. |last4=Palacios |first4=D. M. |last5=Lowry |first5=M. S. |last6=Aurioles-Gamboa |first6=D. |last7=Snell |first7=H. M. |last8=Escorza-Treviño |first8=S. |year=2009 |title=Phylogeography of California and Galápagos sea lions and population structure within the California sea lion |journal=Marine Biology |volume=156 |issue=7 |pages=1375–1387 |doi=10.1007/s00227-009-1178-1 |bibcode=2009MarBi.156.1375S |s2cid=86062338 |issn=0025-3162 |url=http://swfsc.noaa.gov/uploadedFiles/Divisions/PRD/Programs/Coastal_Marine_Mammal/Zc%20Gentics_Schramm%20et%20al.pdf}}</ref> The U.S. stock breeds mainly in the [[Channel Islands of California|Channel Islands]], although some breeding sites may be established in [[northern California]], and females are now commonly found there.<ref name="iucn status 11 November 2021" /> The Western Baja California stock mainly breeds near [[Punta Eugenia]] and at [[Isla Santa Margarita]]. The above-mentioned stocks are separated by the Ensenada Front. The stocks of the Gulf of California live in the shallow waters of the north (Northern stock), the [[tidal island]]s near the center (Central stock), and the mouth of the bay (Southern stock). The stock status of the California sea lions at the deep waters of the central bay has not been analyzed.<ref name=populations/>

Vagrants can reach the north-western Pacific such as on the [[Commander Islands]].<ref>Commander Islands Nature and Biosphere Reserve. [http://komandorsky.ru/zalophus-californianus-lesson.html California sea lion Zalophus californianus Lesson, 1828]. Retrieved on August 24, 2017</ref> Although several otariinae have been recorded around the Japanese archipelago in recent years, their exact origins are unclear.<ref>[http://svrsh1.kahaku.go.jp/marmam/?p=4354 鹿児島県薩摩川内市で種不明アシカ出現] {{Webarchive|url=https://archive.today/20160602094922/http://svrsh1.kahaku.go.jp/marmam/?p=4354 |date=2016-06-02 }}- 海棲哺乳類情報データベース</ref>

[[File:Zalophus californianus2.jpg|thumb|right|California sea lions in [[Santa Cruz, California|Santa Cruz]], California]]
During the breeding season, California sea lions gather on both sandy and rocky shores. On warm days, they lie closer to the water. At night or in cool weather, they travel farther inland or to higher elevations.<ref name=Audubon/> Non-breeding individuals may gather at [[marina]]s, [[Wharf|wharves]], or even navigational [[buoy]]s. California sea lions can also live in [[fresh water]] for periods of time, such as near [[Bonneville Dam]], nearly {{convert|150|mi|}} up the [[Columbia River]].<ref name=WDFW>{{cite web |title=Columbia River Sea Lion Management: Restoring balance between predators and salmon |publisher=Washington Department of Fish & Wildlife |url=http://wdfw.wa.gov/conservation/sealions/ |access-date=23 May 2012 |archive-url=https://web.archive.org/web/20171021212903/http://wdfw.wa.gov/conservation/sealions/ |archive-date=21 October 2017 |url-status=dead |df=dmy-all }}</ref> In 2004, a healthy California sea lion was found sitting on a road in [[Merced County]], California, almost a hundred miles upstream from the [[San Francisco Bay]] and half a mile from the [[San Joaquin River]].<ref name=Merced>{{cite news |last=Kay |first=Jane |title=When good fishing trips go bad: Sea lion swims the Delta – lands on Merced County farm road |newspaper=[[San Francisco Chronicle]] |date=10 February 2012 |url=http://www.sfgate.com/default/article/When-good-fishing-trips-go-bad-Sea-lion-swims-2798458.php |access-date=3 July 2012}}</ref>

===Diet and predation===
California sea lions feed on a wide variety of [[Marine life|seafood]], mainly [[squid]] and [[fish]], and sometimes [[clam]]s. Commonly eaten fish and squid species include [[salmon]], [[hake]], [[Pacific whiting]], [[anchovy]], [[herring]], [[Shortraker rockfish|rockfish]], [[lamprey]], [[Squaliformes|dogfish]], and [[Opalescent inshore squid|market squid]].<ref>{{cite web |title=Sea Lion Diet |publisher=Southwest Fisheries Science Center |url=http://swfsc.noaa.gov/textblock.aspx?Division=PRD&ParentMenuId=148&id=1252 |access-date=2 September 2007}}</ref> They mostly forage near mainland coastlines, the [[continental shelf]], and [[seamount]]s. They may also search along the ocean bottom.<ref name=Audubon/> California sea lions may eat alone or in small to large groups, depending on the amount of food available. They sometimes cooperate with other predators, such as [[dolphin]]s, [[porpoise]]s, and [[seabird]]s, when hunting large schools of fish.<ref>{{cite book |last=Riedman |first=M. |year=1991 |title=The Pinnipeds: Seals, Sea lions, and Walruses |url=https://archive.org/details/pinnipedssealsse0000ried |url-access=registration |publisher=[[University of California Press]] |page=[https://archive.org/details/pinnipedssealsse0000ried/page/168 168] |isbn=978-0520064980}}</ref> California sea lions sometimes follow dolphins and [[Kleptoparasitism|exploit their hunting efforts]].<ref name=Perrin/> Adult females feed between {{convert|10|–|100|km|mi|abbr=on}} from shore.<ref name=Lowry>{{cite journal |year=1999 |title=Market squid (''Loligo opalescens'') in the diet of California sea lions (''Zalophus californianus'') in southern California (1981–1995) |url=http://www.calcofi.ucsd.edu/newhome/publications/CalCOFI_Reports/v40/pdfs/Vol_40_Lowry___Carretta.pdf |journal=Reports of California Cooperative Oceanic Fisheries Investigations |volume=40 |pages=196–207 |last1=Lowry |first1=M.S. |last2=Carretta |first2=J.V. |url-status=dead |archive-url=https://web.archive.org/web/20130412155231/http://www.calcofi.ucsd.edu/newhome/publications/CalCOFI_Reports/v40/pdfs/Vol_40_Lowry___Carretta.pdf |archive-date=2013-04-12 }}</ref> Adult males may forage as far as {{convert|450|km|mi|abbr=on}} from shore when water temperatures rise.<ref>{{cite journal |last1=Weise |first1=Michael J. |last2=Costa |first2=Daniel P. |last3=Kudela |first3=Raphael M. |year=2006 |title=Movement and diving behavior of male California sea lion (''Zalophus californianus'') during anomalous oceanographic conditions of 2005 compared to those of 2004 |journal=[[Geophysical Research Letters]] |volume=33 |issue=22 |pages=L22S10 |doi=10.1029/2006GL027113 |bibcode=2006GeoRL..3322S10W |doi-access=free }}</ref> They also have learned to feed on [[Rainbow trout|steelhead]] and salmon below [[fish ladder]]s at Bonneville Dam and at other locations where fish must queue in order to pass through dams and locks that block their passage.

California sea lions are preyed on by [[orca]]s and large [[shark]]s. At [[Monterey Bay]], California sea lions appear to be the more common food items for transient mammal-eating orcas pods.<ref>{{cite web |last1=Ternullo |first1=Richard |last2=Black |first2=Nancy |title=Predation Behavior of Transient Killer Whales in Monterey Bay, California |publisher=Monterey Bay Whale Watch |access-date=23 May 2012 |url=http://www.montereybaywhalewatch.com/Features/KillerWhalePredation0210.htm}}</ref> The California sea lions may respond to the dorsal fin of a killer whale and remain vigilant, even when encountering resident fish-eating pods.<ref>{{cite journal |last1=Baird |first1=Robin W. |last2=Stacey |first2=Pam J. |year=1989 |title=Observations on the reactions of sea lions, ''Zalophus californianus'' and ''Eumetopias jubatus'', to killer whales, ''Orcinus orca''; evidence of "prey" having a "search image" for predators |journal=[[Canadian Field-Naturalist]] |volume=103 |issue=3 |pages=426–428 |doi=10.5962/p.356188 |url=http://www.cascadiaresearch.org/robin/sealionkwCFN.pdf |access-date=23 May 2012}}</ref> California sea lions are also common prey for [[great white shark]]s. They have been found with scars made by attacks from both great white sharks and [[shortfin mako shark]]s. Sharks attack California sea lions by ambushing them while they are resting at the surface.<ref>{{cite web |last1=Harris |first1=Jeffrey D. |last2=Melin |first2=Sharon R. |last3=DeLong |first3=Robert L. |title=Shark-inflicted Lesions on California Sea Lions (''Zalophus californianus'') at San Miguel Island, California: a New Phenomenon |publisher=National Marine Mammal Laboratory – Alaska Fisheries Science Center |access-date=23 May 2012 |url=ftp://ftp.afsc.noaa.gov/posters/pHarrisJ01_shark-inflicted-lesions.pdf |archive-url=https://wayback.archive-it.org/all/20120712153430/ftp://ftp.afsc.noaa.gov/posters/pHarrisJ01_shark-inflicted-lesions.pdf |url-status=dead |archive-date=12 July 2012 }}</ref> California sea lions that are attacked in the hindquarters are more likely to survive and make it to the shore.<ref>{{cite book |last1=Long |first1=Douglas J. |last2=Hanni |first2=Krista D. |last3=Pyle |first3=Peter |last4=Roletto |first4=Jan |last5=Jones |first5=Robert E. |last6=Bandar |first6=Raymond |year=1995 |contribution=White Shark Predation on Four Pinniped Species in Central California Waters: Geographic and Temporal Patterns Inferred from Wounded Carcasses |pages=263–274 |title=Great White Sharks: The Biology of Carcharodon carcharias |editor1-last=Klimley |editor1-first=A. Peter |editor2-last=Ainley |editor2-first=David G. |publisher=[[Academic Press]] |isbn=978-0124150317}}</ref>
{{Clear}}

==Life history==
===Reproductive behavior and parenting===
[[File:Sea lion beach.jpg|thumb|California sea lion rookery]]
California sea lions breed gregariously between May and August, when they arrive at their breeding [[Rookery|rookeries]]. When establishing a [[Territory (animal)|territory]], the males will try to increase their chances of reproducing by staying on the rookery for as long as possible. During this time, they will [[Fasting|fast]], relying on a thick layer of fat called [[blubber]] for energy. Size and patience allow a male to defend his territory more effectively; the bigger the male, the more blubber he can store and the longer he can wait. A male California sea lion usually keeps his territory for around 27 days. Females have long [[parturition]] intervals, and thus the males do not establish their territories until after the females give birth. Most fights occur during this time. After this, the males rely on ritualized displays (vocalizations, head-shaking, stares, bluff lunges, and so on) to maintain their territorial boundaries. Since temperatures can reach over {{convert|30|C|F|0|abbr=on}} during this time, males must include water within their territories. Some territories are underwater, particularly those near steep cliffs.<ref name=Odell>{{cite book |last=Odell |first=D.K.|contribution=The Fight to Mate: Breeding strategy of California sea lions |pages=172–173 |title=The Encyclopedia of Mammals |editor-last=MacDonald |editor-first=David |publisher=[[Oxford University Press]] |edition=2nd |year=2001 |isbn=978-0760719695}}</ref> California sea lions that fail to establish a territory are driven out to sea or gather at a nearby beach.<ref name=Perrin/>
[[File:Sea lion mother and pup.jpg|thumb|left|California sea lion mother with pup]]
Before mating begins, females gather into "milling" groups of 2–20 individuals. The females in these groups will mount each other as well as the males. These groups begin to disintegrate as the females begin to mate.<ref name=Perrin/> The territorial and mating system of the California sea lion has been described as similar to a [[Lek (biology)|lek]] system, as females appear to choose their mates while moving through different territories.<ref>{{cite journal |last1=García-Aguilar |first1=M.C. |last2=Aurioles-Gamboa |first2=D. |year=2003 |title=Breeding season of the California sea lion (''Zalophus californianus'') in the Gulf of California, Mexico |journal=Aquatic Mammals |volume=29 |issue=10 |pages=67–76 |doi=10.1578/016754203101024086}}</ref> They avoid males that are too aggressive or energetic. Males are usually unable to prevent females from leaving their territories,<ref name=Perrin/> particularly in water.<ref name=Flatz/> Mating may occur outside the rookeries, between non-territorial males and females, as the latter move to and from the mating site. In some rookeries, [[copulation (zoology)|copulation]] may be monopolized by a few males, while at others, a single male may sire no more than four pups.<ref name=Flatz>{{cite journal |last1=Flatz |first1=Ramona |last2=González-Suárez |first2=Manuela |last3=Young |first3=Julie K. |last4=Hernández-Camacho |first4=Claudia J. |last5=Immel |first5=Aaron J. |last6=Gerber |first6=Leah R.|author-link6=Leah Gerber |year=2012 |title=Weak Polygyny in California Sea Lions and the Potential for Alternative Mating Tactics |journal=[[PLoS ONE]] |volume=7 |issue=3 |page=e33654 |doi=10.1371/journal.pone.0033654 |editor-last=Fenton |editor-first=Brock|bibcode = 2012PLoSO...733654F |pmid=22432039 |pmc=3303858|doi-access=free }}</ref>

Female California sea lions have a 12-month reproductive cycle, consisting of a 9-month actual [[gestation]] and a 3-month [[delayed implantation]] of the fertilized egg before giving birth in June or July. Interbirth intervals are particularly long for this species, being 21 days for sea lions off California and more than 30 days for sea lions in the Gulf of California.<ref name=Flatz/> Females remain with their pups onshore for 10 days and nurse them. After this, females will go on foraging trips lasting as long as three days, returning to nurse their pups for up to a day. Pups left onshore tend to gather in nurseries to socialize and play.<ref name=Audubon/> When returning from a trip, females call their pups with distinctive calls to which the pups will reply in kind. A mother and pup can distinguish each other's calls from those of other mothers and pups. At first, reunions largely depend on the efforts of the mothers. However, as pups get older, they get more involved in reunions.<ref>{{cite journal |last1=Gisiner |first1=Robert |last2=Schusterman |first2=Ronald J. |year=1991 |title=California sea lion pups play an active role in reunions with their mothers |journal=[[Animal Behaviour (journal)|Animal Behaviour]] |volume=41 |issue=2 |pages=364–66 |doi=10.1016/S0003-3472(05)80488-9|s2cid=53149333 }}</ref> Older pups may sometimes join their mothers during their foraging trips.<ref name=Audubon/> Adult male California sea lions play no role in raising pups, but they do take more interest in them than adult males of other otariid species; they have even been observed to help shield swimming pups from predators.<ref name=Walker/> Pups are weaned by a year but can continue to suckle for another year.<ref name=Perrin/>

===Communication===
[[File:California sea lions chasing a boat.webm|thumb|Barking California sea lions pursuing a boat]]
California sea lions communicate with a range of vocalizations. The most commonly used one is their characteristic [[Bark (utterance)|bark]]. Territorial males are the loudest and most continuous callers, and barks are produced constantly during the peak of the breeding season. California sea lions bark especially rapidly when excited. The barks of territorial and non-territorial males sound similar, although those of the former are deeper. Males may bark when threatening other males or during courtship. The only other vocalization made by territorial males is a "prolonged hoarse grunt sound" made when an individual is startled by a human. This vocalization is also made by groups of non-reproductive males.<ref name=Peterson>{{cite journal |last1=Peterson |first1=Richard S. |last2=Bartholomew |first2=George A. |year=1969 |title=Airborne vocal communication in the California sea lion, ''Zalophus californianus'' |journal=[[Animal Behaviour (journal)|Animal Behaviour]] |volume=17 |issue=1 |pages=17–24 |doi=10.1016/0003-3472(69)90108-0}}</ref>

Female California sea lions are less vocal. Their barks, high-pitched and shorter than those made by males, are used in aggressive situations. Other aggressive vocalizations given by females include the "squeal", the "belch", and the "growl". The sound a female California sea lion gives when calling her pups is called a "pup-attraction call", described as "loud" and "brawling". Pups respond with a "mother-response call", which is similar in structure. Pups will also bleat or bark when playing or in distress.<ref name=Peterson/> California sea lions can produce vocalizations underwater. These include "whinny" sounds, barks, buzzings, and clicks.<ref>{{cite journal |last1=Schusterman |first1=Ronald J. |last2=Gentry |first2=Roger |last3=Schmook |first3=James |year=1966 |title=Underwater Vocalization by Sea Lions: Social and Mirror Stimuli |journal=[[Science (journal)|Science]] |volume=154 |issue=3748 |pages=540–542 |doi= 10.1126/science.154.3748.540|pmid=5916951 |bibcode = 1966Sci...154..540S |s2cid=26768330 }}</ref>

===Nonbreeding activities===
Outside the breeding season, males migrate to the northern ends of the species range to feed, while females forage near the breeding rookeries.<ref name=Perrin/> California sea lions can stay at sea for as long as two weeks at a time. They make continuous dives, returning to the surface to rest. California sea lions may travel alone or in groups while at sea and [[Hauling-out|haul-out]] between each sea trip. Adult females and juveniles molt in autumn and winter; adult males molt in January and February. California sea lions in the Gulf of California do not migrate; they stay in the Gulf of California year-round.<ref name=Flatz/>

==Intelligence and trainability==
[[File:US Navy 030213-N-3783H-011 Zak, a 375-pound California sea lion, leaps back into the boat after a harbor-patrol training mission.jpg|thumb|250px|left|Zak, a {{convert|375|lb|kg|0|abbr=on|adj=on}} California sea lion of the Navy leaps back into the boat after a harbor-patrol training mission.]]
Marine biologist Ronald J. Schusterman and his research associates have studied the California sea lions' cognitive ability. They have discovered that California sea lions are able to recognize relationships between [[Stimulus (psychology)|stimuli]] based on similar functions or connections made with their peers, rather than only the stimuli's common features.<ref>{{cite journal |last1=Schusterman |first1=Ronald J. |last2=Kastak |first2=David |year=1993 |title=A California sea lion (''Zalophus californianus'') is capable of forming equivalence relations |journal=Psychological Record |volume=43 |issue=4 |pages=823–839 |issn=0033-2933 |url=http://pinnipedlab.ucsc.edu/publications/pub_080_1993.pdf |doi=10.1007/BF03395915 |s2cid=147715775 |access-date=2012-05-30 |archive-url=https://web.archive.org/web/20130513041845/http://pinnipedlab.ucsc.edu/publications/pub_080_1993.pdf |archive-date=2013-05-13 |url-status=dead }}</ref> California sea lions have demonstrated the ability to understand simple syntax and commands when taught an artificial [[sign language]]. However, California sea lions rarely used the signs semantically or logically.<ref>{{cite journal |last1=Gisiner |first1=R. |last2=Schusterman |first2=R.J. |year=1992 |title=Sequence, syntax, and semantics: Responses of a language-trained sea lion (''Zalophus californianus'') to novel sign combinations |journal=Journal of Comparative Psychology |volume=106 |pages=78–91 |url=http://pinnipedlab.ucsc.edu/publications/pub_077_1992.pdf |doi=10.1037/0735-7036.106.1.78 |access-date=2012-05-30 |archive-url=https://web.archive.org/web/20181119152347/https://pinnipedlab.ucsc.edu/publications/pub_077_1992.pdf |archive-date=2018-11-19 |url-status=dead }}</ref> In 2011, a California sea lion named Ronan was recorded bobbing her head in synchronization to musical rhythms.<ref>{{cite news |url=http://news.ucsc.edu/2013/04/sea-lion-beat.html |work=[[University of California, Santa Cruz]] |title=Sea lion defies theory and keeps the beat |first=Tim |last=Stephens |date=1 April 2013 |access-date=12 April 2013}}</ref>
This "[[Entrainment (biomusicology)|rhythmic entrainment]]" was previously seen only in humans, parrots and other birds possessing vocal mimicry.<ref>{{cite journal|author1=Cook, F. |author2=Rouse, A. |author3=Wilson, M. |author4=Reichmuth, M. |s2cid=34580113 |year=2013|title=A California sea lion (''Zalophus californianus'') can keep the beat: motor entrainment to rhythmic auditory stimuli in a non vocal mimic|journal=Journal of Comparative Psychology|doi=10.1037/a0032345|pmid=23544769|volume=127|issue=4 |pages=412–27}}</ref>
[[File:California Sea Lion Show.ogv|thumb|right|Captive California sea lion performing]]
[[File:Sea lion, Central Park Zoo.jpg|thumb|A California sea lion at [[Central Park Zoo]]. It has climbed to the edge of its tank awaiting feeding, showing awareness of its regular feeding time.]]
Because of their intelligence and trainability, California sea lions have been used by [[circus]]es and [[marine mammal park]]s to perform various tricks such as throwing and catching balls on their noses, running up ladders, or honking horns in a musical fashion. Trainers reward their animals with fish, which motivates them to perform. For ball balancing, trainers toss a ball at a California sea lion so it may accidentally balance it or hold the ball on its nose, thereby gaining an understanding of what to do. A California sea lion may go through a year of training before performing a behavior for the public. However, its memory allows it to perform a behavior even after three months of resting.<ref name=Walker>{{cite book |last=Nowak |first=Ronald M. |year=2003 |title=Walker's Marine Mammals of the World |publisher=[[Johns Hopkins University Press]] |pages=80–83 |isbn=978-0801873430}}</ref> Some organizations, such as the [[Humane Society of the United States]] and [[World Animal Protection]], object to using California sea lions and other marine mammals for entertainment, claiming the tricks are "exaggerated variations of their natural behaviors" and distract the audience from the animal's unnatural environment.<ref>{{cite web |title=The Case Against Marine Mammals in Captivity |publisher=[[Humane Society of the United States]] and [[World Animal Protection]] |page=3 |url=http://www.humanesociety.org/assets/pdfs/marine_mammals/case_against_marine_captivity.pdf |access-date=30 May 2012 |archive-date=30 September 2018 |archive-url=https://web.archive.org/web/20180930105929/http://www.humanesociety.org/assets/pdfs/marine_mammals/case_against_marine_captivity.pdf |url-status=dead }}</ref>

The California sea lion is used in [[Military animal|military applications]] by the [[U.S. Navy Marine Mammal Program]], including detecting [[naval mine]]s and enemy divers. In the [[Persian Gulf]], the animals can swim behind divers approaching a US naval ship and attach a [[Clamp (tool)|clamp]] with a rope to the diver's leg. Navy officials say California sea lions can do this in seconds, before the enemy realizes what happened.<ref>{{cite news |url=https://www.usatoday.com/news/world/iraq/2003-02-16-sealions-usat_x.htm |work=[[USA Today]] |title=Sea lions called to duty in Persian Gulf |first=Donna |last=Leinwand |date=17 February 2003 |access-date=28 April 2010}}</ref> Organizations like [[PETA]] believe that such operations put the animals in danger.<ref>{{cite web|author=Kreider, R.|date=May 31, 2011|title=The Real Navy Seals – and Sea Lions and Dolphins and Whales|work=ABC News|access-date=July 30, 2013|url=https://abcnews.go.com/Blotter/navy-sea-lions-dolphins-find-mines/story?id=13693585}}</ref> However, the Navy insists that California sea lions are removed once their mission is complete.<ref>{{cite web|title=Frequently Asked Questions|publisher=U.S. Navy Marine Mammal Program|access-date=July 30, 2013|url=http://www.public.navy.mil/spawar/Pacific/71500/Pages/faqs.aspx|archive-url=https://web.archive.org/web/20130619231851/http://www.public.navy.mil/SPAWAR/PACIFIC/71500/Pages/faqs.aspx|archive-date=June 19, 2013|url-status=dead|df=mdy-all}}</ref>

==Status==
[[File:Sealions on Pier 39, SF, CA, jjron 26.03.2012.jpg|thumb|Hundreds of California sea lions bask on Pier 39 in San Francisco, where they are welcomed as a [[tourist attraction]]. |alt=Photo of sea lions crowded together on dock]]
The [[International Union for Conservation of Nature|IUCN]] lists the California sea lion as Least Concern due to "its large and increasing population size."<ref name="iucn status 11 November 2021" /> The estimated population is 238,000–241,000 for the U.S. or Pacific Temperate stock, 75,000–85,000 for the Western Baja California or Pacific Tropical stock, and 31,393 for the population in the Gulf of California.<ref name=populations/> Off the [[Pacific coast of the United States]], California sea lions are so numerous that they are close to [[carrying capacity]], while the Gulf of California population declined by 20% by 2008. California sea lions may be killed when in conflict with [[Fisherman|fishermen]], by [[poaching]], and by entanglements in human-made garbage. They are also threatened by pollutants like [[DDT]] and [[Polychlorinated biphenyl|PCB]] which accumulate in the marine food chain.<ref name="iucn status 11 November 2021" />
[[File:100-Shooting Sea Lions.jpg|thumb|Shooting California sea lions, ca. 1870s]]

In the United States, the California sea lion is protected on the federal [[Marine Mammal Protection Act of 1972|Marine Mammal Protection Act]] (MMPA), passed in 1972, which outlaws hunting, killing, capture, and harassment of the animal. In 1994 an amendment to the Act allowed for the possibility of limited lethal removal of pinnipeds preying on endangered salmonids should the level of predation be documented to have a significant adverse impact on the decline or recovery of ESA-listed salmonids.<ref>{{Cite web|url=http://www.gpo.gov/fdsys/pkg/USCODE-2012-title16/pdf/USCODE-2012-title16-chap31-subchapII-sec1389.pdf|title=16 U.S.C. § 1389}}</ref> Applications have been granted for removal of several individual California sea lions at Ballard Locks<ref>{{Cite web|url=http://www.gpo.gov/fdsys/pkg/FR-1996-03-26/pdf/96-7184.pdf#page=1|title=61 Fed. Reg. 13153 (March 26, 1996)}}</ref> and at the Bonneville Dam, where up to 92 California sea lions can be killed each year for a 5-year period.<ref>{{cite web |title=NOAA authorizes states to remove California sea lions that threaten protected salmon |publisher=[[National Oceanic and Atmospheric Administration]] |access-date=17 October 2013 |url=http://www.nwr.noaa.gov/publications/news_releases/2012/2012_0315.pdf |archive-url=https://web.archive.org/web/20131022135316/http://www.nwr.noaa.gov/publications/news_releases/2012/2012_0315.pdf |archive-date=22 October 2013 |url-status=dead }}</ref>  Wildlife officials have unsuccessfully attempted to ward off the sea lions using [[bomb]]s, [[rubber bullet]]s and [[Bean bag round|bean bags]].<ref name=warrant>{{cite web |author=Haight, A. |date=9 March 2010 |title=Sea lion death warrants |publisher=[[KATU]] |access-date=9 June 2012 |url=http://www.katu.com/outdoors/featured/87172472.html |url-status=dead |archive-url=https://web.archive.org/web/20130510204327/http://www.katu.com/outdoors/featured/87172472.html |archive-date=10 May 2013 }}</ref> Efforts to chase sea lions away from the area have also proven ineffective.<ref>{{cite web |title=Columbia River Sea Lion Management: Restoring balance between predators and salmon |publisher=Washington State Department of Fish & Wildlife |url=http://wdfw.wa.gov/conservation/sealions/ |access-date=23 May 2012 |archive-url=https://web.archive.org/web/20171021212903/http://wdfw.wa.gov/conservation/sealions/ |archive-date=21 October 2017 |url-status=dead  }}</ref>
Critics have objected to the killing of the California sea lions, pointing out that the level of mortality permitted as a result of recreational and commercial fisheries in the river and as part of the operation of [[Hydroelectricity|hydroelectric dams]] pose a greater threat to the salmon.<ref>{{cite web |title=Bonneville Dam Sea Lions Under Siege |publisher=[[The Humane Society of the United States]] |access-date=17 October 2013 |url=http://www.humanesociety.org/issues/fisheries/timelines/bonneville_dam_sea_lions_under_siege.html |archive-date=18 October 2013 |archive-url=https://web.archive.org/web/20131018010205/http://www.humanesociety.org/issues/fisheries/timelines/bonneville_dam_sea_lions_under_siege.html |url-status=dead }}</ref>

These animals exploit more human-made environments like docks for haul-out sites. Many docks are not designed to withstand the weight of several resting California sea lions which cause major tilting and other problems. Wildlife managers have used various methods to control the animals and some city officials have redesigned docks so they can better withstand them.<ref>{{cite web|author=French, C.|date=April 10, 2013|title=Sea Lions Take Over Ventura Docks|publisher=the Log.com|access-date=August 17, 2013|url=http://www.thelog.com/Local/Article/Sea-Lions-Take-Over-Ventura-Docks}}</ref><ref>{{cite web|author=Bruscas, A.|date=July 27, 2012|title=Shocking new idea for sea lion control|publisher=The Daily World.com|access-date=August 17, 2013|url=http://thedailyworld.com/sections/news/local/shocking-new-idea-sea-lion-control.html|url-status=dead|archive-url=https://web.archive.org/web/20130921054643/http://thedailyworld.com/sections/news/local/shocking-new-idea-sea-lion-control.html|archive-date=September 21, 2013}}</ref>

===2015 Californian shore sea lions pups crisis===
In January and February 2015, 1450 malnourished or sick California sea lion pups were found along stretches of the California coast, and estimations give a higher number of dead pups. The [[National Oceanic and Atmospheric Administration]] has pointed to unprecedentedly warm Pacific coastal waters, related to [[Pacific decadal oscillation]] and [[El Niño]], as the likely cause. Elevated water temperatures reduced the abundance of anchovies, sardines and mackerel, principal components of the California sea lion pup diet during nursery season.<ref name=TSB>{{Cite news|title=Sick, starving sea lion pups wash up in record numbers on California coast|url=http://www.sacbee.com/news/local/environment/article12965981.html|access-date=12 March 2015|date=2015-03-07|newspaper=The Sacramento Bee|last1=Hecht|first1=Peter}}</ref> This caused many California sea lion pups to starve, while others died when they took to open waters in search of food at too early an age.<ref>{{cite web|title=More Than 100 Sick Sea Lion Flooded On California Coastline  |url=http://newstonight.co.za/content/more-100-sick-sea-lion-flooded-california-coastline|access-date=12 March 2015}}</ref>
Several months earlier, in the summer of 2014, [[Cassin's auklet#2014 summer mass death in US|a large number of Cassin's auklet chicks died]] during the fledging period due to similar circumstances brought about by elevated water temperatures.<ref>{{cite web|title=Mass Death of Seabirds in Western U.S. Is 'Unprecedented'|url=http://news.nationalgeographic.com/news/2015/01/150123-seabirds-mass-die-off-auklet-california-animals-environment/|archive-url=https://web.archive.org/web/20150126090147/http://news.nationalgeographic.com/news/2015/01/150123-seabirds-mass-die-off-auklet-california-animals-environment|url-status=dead|archive-date=January 26, 2015|website=news.nationalgeographic.com/|access-date=12 March 2015|date=2015-01-24}}</ref>

===Oregon and Washington state governments annual killings===
In November 2018, the State of Oregon obtained a permit to kill 93 California sea lions per year below Willamette Falls. Under a similar program, Oregon and Washington had killed over 150 California sea lions on the Columbia River by January 2019. In both cases, the purpose was to protect the local populations of fish (such as trout or salmon) from predation by the sea lions.<ref>{{cite news |last1=GILLIAN FLACCUS |title=Oregon begins killing sea lions after relocation fails |url=https://apnews.com/7e0991fa9f7f404e904bb271999b6e59 |access-date=10 January 2019 |work=Associated Press |date=10 January 2019 |quote=In a similar program, Oregon and Washington have already killed more than 150 sea lions below the Bonneville Dam on the Columbia River to protect threatened and endangered salmon.}}</ref><ref>{{cite web |title=California Sea Lion Management: Restoring balance between predators and salmon |publisher=[[Oregon Department of Fish and Wildlife]] |access-date=17 October 2013 |url=http://www.dfw.state.or.us/fish/SeaLion/ |archive-date=17 October 2013 |archive-url=https://web.archive.org/web/20131017233114/http://www.dfw.state.or.us/fish/SeaLion/ |url-status=dead }}</ref> In August 2020, the federal government authorized the states of Oregon, Washington, and Idaho as well as six [[Indian tribes in the United States|regional tribes]] to cull sea lions that preyed upon endangered species of fish in the [[Columbia River]] basin, allowing for the killing of up to 540 California sea lions and 176 Steller sea lions over the following five years.<ref>{{Cite web |date=<!-- 3:04 PM PDT --> August 14, 2020 |title=U.S. allows killing sea lions eating at-risk Northwest salmon |url=https://www.kgw.com/article/tech/science/environment/us-allows-killing-sea-lions-eating-at-risk-northwest-salmon/281-a8855794-eb91-4bca-87f3-03b47d20b843 |access-date=2023-11-05 |website=kgw.com |language=en-US}}</ref> Between 2020 and April 2023, Oregon killed 99 sea lions as part of this program.<ref>{{Cite web |date=<!-- 4:45 PM PDT --> April 11, 2023 |title=Battle over endangered fish has led Oregon to cull sea lions |url=https://www.kgw.com/article/tech/science/environment/oregon-killing-sea-lions-endangered-salmon-fish/283-6b208fa4-d642-411b-9574-d6096dbfdf73 |access-date=2023-11-05 |website=kgw.com |language=en-US}}</ref>

==References==
{{Reflist|30em}}

==External links==
{{Portal|Animals|Mammals|Marine life}}
*{{Commons-inline|Category:Zalophus californianus|Zalophus californianus}}
*[https://web.archive.org/web/20171021212903/http://wdfw.wa.gov/conservation/sealions/ WDFW Fact Sheet on sea lions]
*[https://web.archive.org/web/20130412164854/http://www.nwd-wc.usace.army.mil/tmt/agendas/2006/0405_SEALS.pdf USACE information on sea lion deterrents]
*[http://www.mnh.si.edu/mna/image_info.cfm?species_id=421 Smithsonian Institution – North American Mammals: Zalophus californianus]
*[http://cetus.ucsd.edu/voicesinthesea_org/species/pinnipeds/caSeaLion.html Voices in the Sea - Sounds of the California Sea Lion] {{Webarchive|url=https://web.archive.org/web/20140709235836/http://cetus.ucsd.edu/voicesinthesea_org/species/pinnipeds/caSeaLion.html |date=2014-07-09 }}
* {{SealifePhotos|255003}}

{{Carnivora|C1.}}

{{Taxonbar|from=Q379732}}
{{Authority control}}

[[Category:Zalophus]]
[[Category:Pinnipeds of North America]]
[[Category:Western North American coastal fauna]]
[[Category:Mammals of Canada]]
[[Category:Mammals of Mexico]]
[[Category:Mammals of the United States]]
[[Category:Fauna of the Western United States]]
[[Category:Fauna of Gulf of California islands]]
[[Category:Fauna of California]]
[[Category:Fauna of the San Francisco Bay Area]]
[[Category:Mammals described in 1828]]
[[Category:Taxa named by René Lesson]]
[[Category:Articles containing video clips]]
[[Category:Least concern biota of the United States]]
[[Category:Least concern biota of North America]]
[[Category:Biota of the Temperate Northern Pacific]]