Editing Northern elephant seal (section)

==Social behavior and reproduction==
[[File:Northern elephant seal bulls in Ano Nuevo State Park.PNG|thumb|Two males confront one another at [[Año Nuevo State Park]] in California.]]
[[File:Northern elephant seals fighting.webm|thumb|Male elephant seals fighting for mates]]
Northern elephant seals return to their terrestrial [[Habitat|breeding ground]] in December and January, with the bulls arriving first. The bulls haul out on isolated or otherwise protected beaches, typically on islands or very remote mainland locations. It is important that these beach areas offer protection from the winter storms and high surf wave action.<ref name="Pup">{{cite journal| vauthors = Riedman ML, Le Boeuf BJ |title=Mother-pup separation and adoption in northern elephant seals|jstor=4599535|journal=Behav. Ecol. Sociobiol.|volume=11|pages=203–213|doi=10.1007/BF00300063|year=1982|issue=3|bibcode=1982BEcoS..11..203R |s2cid=2332005}}</ref> The bulls engage in fights of supremacy to determine which few bulls will achieve a harem.<ref name="Sexual behavior"/><ref name="competition"/>

After the males have arrived on the beach, the females arrive to give birth. Females fast for five weeks and nurse their single pup for four weeks; in the last few days of lactation, females come into estrus and mate.<ref name="Natal">{{cite journal |vauthors=Le Boeuf BJ, Whiting RJ, Gantt RF |title=Perinatal behavior of northern elephant seal females and their young |journal=Behaviour |volume=43 |issue=1 |pages=121–56 |year=1972 |pmid=4656181 |doi=10.1163/156853973x00508 |jstor=4533472 }}</ref> Mating behavior relates to a social hierarchy, and stronger males are considered higher rank than those smaller and weaker.<ref name="Leboeuf 1–26">{{Cite journal |last=Leboeuf |first=Burney J. |date=1972-01-01 |title=Sexual Behavior in the Northern Elephant Seal Mirounga Angustirostris |url=https://brill.com/view/journals/beh/41/1-2/article-p1_1.xml |journal=Behaviour |language=en |volume=41 |issue=1–2 |pages=1–26 |doi=10.1163/156853972X00167 |pmid=5062032 |issn=0005-7959|url-access=subscription }}</ref> In this [[Polygyny in animals|polygynous]] society, a high-ranking bull can have a [[Harem (zoology)|harem]] of 30–100 cows, depending on his size and strength. Males unable to establish harems will wait on the periphery, and will try to mount nearby females. Dominant bulls will disrupt copulations of lower-ranking bulls. They can mount females without interference, but commonly break off to chase off rivals.<ref name="Sexual behavior">{{cite journal |vauthors=Leboeuf BJ |title=Sexual behavior in the Northern Elephant seal Mirounga angustirostris |journal=Behaviour |volume=41 |issue=1 |pages=1–26 |year=1972 |pmid=5062032 |doi=10.1163/156853972X00167 |jstor=4533425 }}</ref> While fights are not usually to the death, they are brutal and often with significant bloodshed and injury; however, in many cases of mismatched opponents, the younger, less capable males are simply chased away, often to upland dunes. In a lifetime, a successful bull could easily sire over 500 pups. Most copulations in a breeding colony are done by only a small number of males and the rest may never be able to mate with a female.<ref name="competition">{{cite journal|author=Le Boeuf BJ |year=1974 |title=Male-male competition and reproductive success in elephant seals |journal=Am. Zool. |volume=14 |pages=163–176 |doi=10.1093/icb/14.1.163 |doi-access=free}}</ref> Copulation is most often on land, and takes roughly five minutes.<ref name="Leboeuf 1–26"/> Pups are sometimes crushed during battles between bulls.<ref name="Pup"/><ref name="competition"/>

[[File:Three Mirounga angustirostris pups nursing.jpg|thumb|Three pups nursing from a single adult female. Female elephant seals deliver only one pup; the two others may have wandered away from their mothers and gotten lost. In this situation, no pup would get enough milk.]] 
After arrival on shore, males fast for three months, and females fast for five weeks during mating and when nursing their pups. The gestation period is about 7 months but the fertilized egg will not attach to the uterine wall for fourth months after copulation. This process is called delayed implantation and is a strategy that allows females to time their arrival to breeding beaches with their time of parturition. One study observed the vast majority of births to take place at night, and in the aforementioned harems. Immediately after birth, a female will turn to her pup and emit a warbling vocalization to attract them, and will continue to throughout the nursing period.<ref name=":0">{{Cite journal |last1=Le Boeuf |first1=Burney J. |last2=Whiting |first2=Ronald J. |last3=Gantt |first3=Richard F. |date=1972 |title=Perinatal Behavior of Northern Elephant Seal Females and Their Young |url=https://www.jstor.org/stable/4533472 |journal=Behaviour |volume=43 |issue=1/4 |pages=121–156 |jstor=4533472 |issn=0005-7959}}</ref> Sometimes, a female can become very aggressive after giving birth and will defend her pup from other females. Such aggression is more common in crowded beaches.<ref name="birth">{{cite journal |vauthors=Christenson TE, Le Boeuf BJ |title=Aggression in the Female Northern Elephant Seal, ''Mirounga angustirostris''|jstor=4533866|journal=Behaviour|volume=64|issue= 1/2 |year=1978|pages=158–172|doi=10.1163/156853978X00495|pmid=564691}}</ref> While most females nurse their own pups and reject nursings from alien pups, some do accept alien pups with their own. An orphaned pup may try to find another female to suckle and some are adopted, at least on Año Nuevo Island.<ref name="Pup"/><ref name="Natal"/> Some pups, known as [[super weaner]]s, may grow to exceptionally large sizes by nursing from other females in addition to their mothers.<ref>{{Cite journal |last1=Reiter |first1=Joanne |last2=Stinson |first2=Nell Lee |last3=Le Boeuf |first3=Burney J. |date=1978 |title=Northern Elephant Seal Development: The Transition from Weaning to Nutritional Independence |url=https://www.jstor.org/stable/4599180 |journal=[[Behavioral Ecology and Sociobiology]] |volume=3 |issue=4 |pages=337–367 |doi=10.1007/BF00303199 |jstor=4599180 |bibcode=1978BEcoS...3..337R |s2cid=13370085 |issn=0340-5443|url-access=subscription }}</ref><ref>{{Cite web |title=Elephant Seals |url=https://www.parks.ca.gov/|access-date=2021-11-25 |website=[[California State Parks]] |language=en}}</ref> Pups nurse about four weeks and are weaned abruptly before being abandoned by their mother, who heads out to sea within a few days. Pups gain weight rapidly during the nursing period, and weigh {{convert|300|-|400|lb|0}} on average upon being weaned.<ref name=":0" /> Left alone, weaned pups will gather into groups and stay on shore for 12 more weeks. The pups learn how to swim in the surf and eventually swim farther to forage. Thus, their first long journey at sea begins.

Elephant seals communicate though various means. Males will threaten each other with the snort, a sound caused by expelling air though their probosces, and the clap-trap, a loud, clapping sound comparable to the sound of a diesel engine. Pups will vocalize when stressed or when prodding their mothers to allow them to suckle. Females make an unpulsed attraction call when responding to their young, and a harsh, pulsed call when threatened by other females, males or alien pups. Elephant seals produce low-frequency sounds, both substrate-borne and air-borne. These sounds help maintain social hierarchy in crowded or noisy environments and reduce energy consumption when fasting.<ref name=species>
{{cite journal |vauthors=Steward BS, Huber HR |title=Mirounga angustirostris |year=1993 |journal=Mammalian Species |issue=449 |pages=1–10 |url=http://www.science.smith.edu/msi/pdf/i0076-3519-449-01-0001.pdf |doi=10.2307/3504174|url-status=dead|archive-url=https://web.archive.org/web/20140318032809/http://www.science.smith.edu/msi/pdf/i0076-3519-449-01-0001.pdf |archive-date=18 March 2014 |jstor=3504174 |s2cid=254007992}}</ref>