Editing California sea lion (section)

==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/>