walrus
{{short description|Species of marine mammal with tusks}}
{{other uses}}
{{pp-protect|small=yes}}
{{Use dmy dates|date=September 2018}}
{{speciesbox
| name = Walrus
| fossil_range = Pleistocene to Recent
| status = VU
| status_system = IUCN3.1
| status2 = CITES_A3
| status2_system = CITES
| status2_ref = {{Cite web|title=Appendices|url=https://cites.org/eng/app/appendices.php|access-date=17 April 2024|website=cites.org}}
| image = Walrus in the Russian Arctic National Park, Novaya Zemlya 2015-2.jpg
| image_caption = Male Atlantic walrus, Novaya Zemlya
| image2 = Walrus 2 (6383855895).jpg
| image2_caption = Female Pacific walrus with young
| genus = Odobenus
| parent_authority = Brisson, 1762
| species = rosmarus
| authority = (Linnaeus, 1758)
| range_map = Odobenus rosmarus map.svg
| range_map_caption = Distribution of walrus
| subdivision_ranks = Subspecies
| subdivision =
O. rosmarus rosmarus
O. rosmarus divergens
O. rosmarus laptevi (debated)
| synonyms =
}}
The walrus (Odobenus rosmarus) is a large pinniped marine mammal with discontinuous distribution about the North Pole in the Arctic Ocean and subarctic seas of the Northern Hemisphere. It is the only extant species in the family Odobenidae and genus Odobenus. This species is subdivided into two subspecies:{{MSW3 Wozencraft|id = 14001024|name-list-style = vanc }} the Atlantic walrus (O. r. rosmarus), which lives in the Atlantic Ocean, and the Pacific walrus (O. r. divergens), which lives in the Pacific Ocean.
Adult walrus are characterised by prominent tusks and whiskers, and considerable bulk: adult males in the Pacific can weigh more than {{convert|2000|kg|lb|abbr=off}}{{cite web | url = http://www.seaworld.org/infobooks/walrus/phycharwal.html | title = Walrus: Physical Characteristics | archive-url = https://web.archive.org/web/20120710175302/http://www.seaworld.org/infobooks/walrus/phycharwal.html | archive-date = 10 July 2012 | work = seaworld.org }} and, among pinnipeds, are exceeded in size only by the two species of elephant seals.{{cite journal| vauthors = Fay FH |year = 1985|url = http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/default.html|title = Odobenus rosmarus|journal = Mammalian Species|pages = 1–7|doi = 10.2307/3503810|issue = 238|jstor = 3503810|access-date = 29 January 2008|archive-url = https://web.archive.org/web/20130915093329/http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/default.html|archive-date = 15 September 2013|url-status = dead|url-access = subscription}} Walrus live mostly in shallow waters above the continental shelves, spending significant amounts of their lives on the sea ice looking for benthic bivalve molluscs. Walruses are relatively long-lived, social animals, and are considered to be a "keystone species" in the Arctic marine regions.
The walrus has played a prominent role in the cultures of many indigenous Arctic peoples, who have hunted it for meat, fat, skin, tusks, and bone. During the 19th century and the early 20th century, walrus were widely hunted for their blubber, walrus ivory, and meat. The population of walruses dropped rapidly all around the Arctic region. It has rebounded somewhat since, though the populations of Atlantic and Laptev walruses remain fragmented and at low levels compared with the time before human interference.
Etymology
File:Walrus on Carta Marina.jpeg (the Carta Marina)]]
The origin of the word walrus derives from a Germanic language, and it has been attributed largely to either Dutch or Old Norse. Its first part is thought to derive from a word such as Old Norse {{Lang|non|hvalr}} ('whale') and the second part has been hypothesized to come from the Old Norse word {{Lang|non|hross}} ('horse').{{cite web | url = http://dictionary.reference.com/browse/walrus | title = Walrus | work = Dictionary.reference.com | access-date = 16 September 2011 }} For example, the Old Norse word {{Lang|non|hrosshvalr}} means 'horse-whale' and is thought to have been passed in an inverted form to both Dutch and the dialects of northern Germany as {{Lang|nl|walros}} and {{Lang|de|Walross}}.{{cite book | vauthors = Nielsen NÅ | title = Dansk Etymologisk Ordbog: Ordenes Historie | publisher = Gyldendal | date = 1976 }} An alternative theory is that it comes from the Dutch words {{Lang|nl|wal}} 'shore' and {{Lang|nl|reus}} 'giant'.{{cite web | url = http://iberianature.com/britainnature/miscellaneous/etymology-of-mammal-names-in-english/ | title = Etymology of mammal names | work = Iberianature.com | date = 29 December 2010 | access-date = 16 September 2011 }}
The species name rosmarus is Scandinavian. The Norwegian manuscript Konungs skuggsjá, thought to date from around AD 1240, refers to the walrus as {{Lang|non|rosmhvalr}} in Iceland and {{Lang|non|rostungr}} in Greenland (walruses were by now extinct in Iceland and Norway, while the word evolved in Greenland). Several place names in Iceland, Greenland and Norway may originate from walrus sites: Hvalfjord, Hvallatrar and Hvalsnes to name some, all being typical walrus breeding grounds.
The archaic English word for walrus—morse—is widely thought to have come from the Slavic languages,{{cite web | url = http://dictionary.oed.com/ | title = morse, n., etymology of | work = The Oxford English Dictionary | edition = 2nd | date = 1989 | publisher = OED Online. Oxford University Press | access-date = 4 October 2007 | archive-date = 25 June 2006 | archive-url = https://web.archive.org/web/20060625103623/http://dictionary.oed.com/ | url-status = dead }} which in turn borrowed it from Finno-Ugric languages, and ultimately (according to Ante Aikio) from an unknown Pre-Finno-Ugric substrate language of Northern Europe.{{cite web | url = https://www.sgr.fi/sust/sust266/sust266_aikio.pdf | title = An essay on Saami ethnolinguistic prehistory | author = Luobbal Sámmol Sámmol Ánte (Ante Aikio) | publisher = Giellagas Institute University of Oulu | page = 85}} Compare {{Lang|ru|морж}} ({{Lang|ru-latn|morž}}) in Russian, {{Lang|fi|mursu}} in Finnish, {{Lang|se|morša}} in Northern Saami, and {{Lang|fr|morse}} in French. Olaus Magnus, who depicted the walrus in the {{Lang|la|Carta Marina}} in 1539, first referred to the walrus as the {{Lang|la|ros marus}}, probably a Latinization of {{Lang|la|morž}}, and this was adopted by Linnaeus in his binomial nomenclature.{{cite book|year = 1880| last = Allen | first = Joel Asaph | name-list-style = vanc |title = History of North American pinnipeds, US Geological and Geographical Survey of the Territorie|publisher = Arno Press Inc. (1974 reprint)|url = {{google books |plainurl=y |id=jFspFxseyC8C}}|isbn = 978-0-405-05702-1}}
The coincidental similarity between morse and the Latin word {{Lang|la|morsus}} ('a bite') supposedly contributed to the walrus's reputation as a "terrible monster".
The compound Odobenus comes from {{lang|grc-Latn|odous}} (Greek for 'teeth') and {{lang|grc-Latn|baino}} (Greek for 'walk'), based on observations of walruses using their tusks to pull themselves out of the water. The term {{Lang|la|divergens}} in Latin means 'turning apart', referring to their tusks.{{CN|date=December 2023}}
The Inuttitut term for the creature is aivik, similar to the Inuktitut word: aiviq ᐊᐃᕕᖅ.{{cite web |title=Inuktut Glossary |url=https://tusaalanga.ca/index.php/glossary |website=Tusaalanga |access-date=3 July 2023}}
Taxonomy and evolution
File:Fossil walrus skull (Odobenus rosmarus).jpg in 1938. At the AMNH. ]]
The walrus is a mammal in the order Carnivora. It is the sole surviving member of the family Odobenidae, one of three lineages in the suborder Pinnipedia along with true seals (Phocidae) and eared seals (Otariidae). While there has been some debate as to whether all three lineages are monophyletic, i.e. descended from a single ancestor, or diphyletic, recent genetic evidence suggests all three descended from a caniform ancestor most closely related to modern bears.{{cite journal | vauthors = Lento GM, Hickson RE, Chambers GK, Penny D | title = Use of spectral analysis to test hypotheses on the origin of pinnipeds | journal = Molecular Biology and Evolution | volume = 12 | issue = 1 | pages = 28–52 | date = January 1995 | pmid = 7877495 | doi = 10.1093/oxfordjournals.molbev.a040189 | doi-access = free }} Recent multigene analysis indicates the odobenids and otariids diverged from the phocids about 20–26 million years ago, while the odobenids and the otariids separated 15–20 million years ago.{{cite journal | vauthors = Arnason U, Gullberg A, Janke A, Kullberg M, Lehman N, Petrov EA, Väinölä R | title = Pinniped phylogeny and a new hypothesis for their origin and dispersal | journal = Molecular Phylogenetics and Evolution | volume = 41 | issue = 2 | pages = 345–54 | date = November 2006 | pmid = 16815048 | doi = 10.1016/j.ympev.2006.05.022 | bibcode = 2006MolPE..41..345A }}{{cite journal | vauthors = Higdon JW, Bininda-Emonds OR, Beck RM, Ferguson SH | title = Phylogeny and divergence of the pinnipeds (Carnivora: Mammalia) assessed using a multigene dataset | journal = BMC Evolutionary Biology | volume = 7 | pages = 216 | date = November 2007 | issue = 1 | pmid = 17996107 | pmc = 2245807 | doi = 10.1186/1471-2148-7-216 | doi-access = free | bibcode = 2007BMCEE...7..216H }} Odobenidae was once a highly diverse and widespread family, including at least twenty species in the subfamilies Imagotariinae, Dusignathinae and Odobeninae.{{cite journal| vauthors = Kohno N |year = 2006|title = A new Miocene Odobenid (Mammalia: Carnivora) from Hokkaido, Japan, and its implications for odobenid phylogeny|journal = Journal of Vertebrate Paleontology|volume = 26|issue = 2|pages = 411–421|doi = 10.1671/0272-4634(2006)26[411:ANMOMC]2.0.CO;2| s2cid=85679558 }} The key distinguishing feature was the development of a squirt/suction feeding mechanism; tusks are a later feature specific to Odobeninae, of which the modern walrus is the last remaining (relict) species.
Two subspecies of walrus are widely recognized: the Atlantic walrus, O. r. rosmarus (Linnaeus, 1758) and the Pacific walrus, O. r. divergens (Illiger, 1815). Fixed genetic differences between the Atlantic and Pacific subspecies indicate very restricted gene flow, but relatively recent separation, estimated at 500,000 and 785,000 years ago.{{cite book|veditors = Hoelzel AR|year = 2002|title = Marine mammal biology: an evolutionary approach|location = Oxford|publisher = Blackwell Publishing|isbn = 978-0-632-05232-5|url = {{google books |plainurl=y |id=OwF05MfTag}}}}{{Dead link|date=October 2023 |bot=InternetArchiveBot |fix-attempted=yes }} These dates coincide with the hypothesis derived from fossils that the walrus evolved from a tropical or subtropical ancestor that became isolated in the Atlantic Ocean and gradually adapted to colder conditions in the Arctic.
The modern walrus is mostly known from Arctic regions, but a substantial breeding population occurred on isolated Sable Island, {{cvt|100|mi}} southeast of Nova Scotia and {{cvt|500|mi}} due east of Portland, Maine, until the early Colonial period.{{cite journal| vauthors = Allen G |year = 1930|title = The Walrus in New England |journal = Journal of Mammalogy |volume = 11|issue = 2 |pages = 139–145 |doi = 10.2307/1374062 | jstor=1374062 }}{{cite web| url= https://www.cbc.ca/news/canada/nova-scotia/sable-island-horses-walruses-1.3335467 |title = Sable Island horses, walruses to be discussed at meeting | website = cbc.ca| date = November 25, 2015| first= Jennifer | last = Henderson | accessdate = July 1, 2023}} Abundant walrus remains have also been recovered from the southern North Sea dating to the Eemian interglacial period, when that region would have been submerged as it is today, unlike the intervening glacial lowstand when the shallow North Sea was dry land.{{cite web |url= https://libstore.ugent.be/fulltxt/RUG01/003/008/245/RUG01-003008245_2021_0001_AC.pdf| publisher= Ghent University| first1 = Hendrik | last1 = Plas |year= 2021| title= Walrus fossils from Het Scheur off the Belgian coast: remains of a late Pleistocene colony?}} Fossils known from San Francisco, Vancouver, and the Atlantic US coast as far south as North Carolina have been referred to glacial periods.{{cite journal | first1 = CR | last1 = Harington | first2 = Graham | last2 = Beard |name-list-style = vanc |year = 1992|title = The Qualicum walrus: a Late Pleistocene walrus (Odobenus rosmarus) skeleton from Vancouver Island, British Columbia, Canada |journal = Annales Zoologici Fennici |volume = 28|issue = 3/4 |pages = 311–319 | jstor = 23735455 |url = http://www.jstor.org/stable/23735455 }}
An isolated population in the Laptev Sea was considered by some authorities, including many Russian biologists and the canonical Mammal Species of the World, to be a third subspecies, O. r. laptevi (Chapskii, 1940), but has since been determined to be of Pacific walrus origin.{{cite web| url= https://nammco.no/wp-content/uploads/2018/10/higdon-stewart-2018-1.pdf|publisher=WWF Arctic Programme| first1 = Jeff W. | last1 = Higdon | first2 = D. Bruce | last2 = Stewart |name-list-style = vanc |year=2018|title=State of Circumpolar Walrus Populations : Odobenus rosmarus|pages = 6}}
Anatomy
File:Walrus2.jpg, showing variation in the curvature and orientation of the tusks and the bumpy skin (bosses) typical of males.|alt=Photo of several walruses, with prominently displayed white pairs of tusks]]
While some outsized Pacific males can weigh as much as {{convert|2000|kg|lb|abbr=on}}, most weigh between {{convert|800|and|1700|kg|lb|abbr=on}}. An occasional male of the Pacific subspecies far exceeds normal dimensions. In 1909, a walrus hide weighing {{convert|500|kg|lb|abbr=on}} was collected from an enormous bull in Franz Josef Land, while in August 1910, Jack Woodson shot a {{convert|4.9|m|ft|frac=2|adj=mid|-long}} walrus, harvesting its {{convert|450|kg|lb|-2|abbr=on}} hide. Since a walrus's hide usually accounts for about 20% of its body weight, the total body mass of these two giants is estimated to have been at least {{convert|2300|kg|lb|-3|abbr=on}}.{{cite book | last = Wood | first = Gerald | name-list-style = vanc | title =The Guinness Book of Animal Facts and Feats| year = 1983 | publisher = Guinness Superlatives | isbn = 978-0-85112-235-9|url={{google books |plainurl=y |id=AWhFAQAAIAAJ}}}} The Atlantic subspecies weighs about 10–20% less than the Pacific subspecies. Male Atlantic walrus weigh an average of {{convert|900|kg|lb|abbr=on}}. The Atlantic walrus also tends to have relatively shorter tusks and somewhat more of a flattened snout. Females weigh about two-thirds as much as males, with the Atlantic females averaging {{convert|560|kg|lb|abbr=on}}, sometimes weighing as little as {{convert|400|kg|lb|abbr=on}}, and the Pacific female averaging {{convert|800|kg|lb|abbr=on}}.{{cite web | vauthors = Carling M | date = 1999 | url = http://141.213.176.11/site/accounts/information/Odobenus_rosmarus.html | title = Odobenus rosmarus walrus | archive-url = https://archive.today/20160320011518/http://141.213.176.11/site/accounts/information/Odobenus_rosmarus.html | archive-date=20 March 2016 | work = Animal Diversity Web }} Length typically ranges from {{convert|2.2|to|3.6|m|ftin|abbr=on}}.{{cite web | first = Tobi | last = McIntyre | name-list-style = vanc | url = http://animals.nationalgeographic.com/animals/mammals/walrus/ | archive-url = https://web.archive.org/web/20100114005532/http://animals.nationalgeographic.com/animals/mammals/walrus/ | url-status = dead | archive-date = 14 January 2010 | title = Walrus. Odobenus rosmarus | work = National Geographic | date = 11 November 2010 }}{{cite web |url=http://www.hww.ca/en/species/mammals/atlantic-walrus.html |title=Hinterland Who's Who – Atlantic walrus |publisher=Hww.ca |access-date=23 June 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120626230539/http://www.hww.ca/en/species/mammals/atlantic-walrus.html |archive-date=26 June 2012 }} Newborn walruses are already quite large, averaging {{convert|33|to|85|kg|lb|abbr=on}} in weight and {{convert|1|to|1.4|m|ftin|abbr=on}} in length across both sexes and subspecies. All told, the walrus is the third largest pinniped species, after the two elephant seals. Walruses maintain such a high body weight because of the blubber stored underneath their skin. This blubber keeps them warm and the fat provides energy to the walrus.
The walrus's body shape shares features with both sea lions (eared seals: Otariidae) and seals (true seals: Phocidae). As with otariids, it can turn its rear flippers forward and move on all fours; however, its swimming technique is more like that of true seals, relying less on flippers and more on sinuous whole body movements. Also like phocids, it lacks external ears.
The extraocular muscles of the walrus are well-developed. This and its lack of orbital roof allow it to protrude its eyes and see in both a frontal and dorsal direction. However, vision in this species appears to be more suited for short-range.{{cite encyclopedia | veditors = Perrin WF, Wursig B, Thewissen JG |encyclopedia=Encyclopedia of Marine Mammals |url={{google books |plainurl=y |id=2rkHQpToi9sC}} |date=26 February 2009 |publisher=Academic Press |isbn=978-0-08-091993-5| vauthors = Kastelein RA |contribution=Walrus Odobenus rosmarus |page=1214 }}
=Tusks and dentition=
File:WalrusBreathing.jpg, Bering Sea|alt=Photo of walrus in ice-covered sea.]]
File:BLW Teeth in the skull of a large Walrus.jpg
While this was not true of all extinct walruses,{{cite journal | vauthors = Magallanes I, Parham JF, Santos GP, Velez-Juarbe J | title = A new tuskless walrus from the Miocene of Orange County, California, with comments on the diversity and taxonomy of odobenids | journal = PeerJ | volume = 6 | pages = e5708 | date = 2018 | pmid = 30345169 | pmc = 6188011 | doi = 10.7717/peerj.5708 | doi-access = free }} the most prominent feature of the living species is its long tusks. These are elongated canines, which are present in both male and female walruses and can reach a length of 1 m (3 ft 3 in) and weigh up to 5.4 kg (12 lb).{{cite book| vauthors = Berta A, Sumich JL |year = 1999|title = Marine mammals: evolutionary biology|publisher = Academic Press|location = San Diego, CA|url={{google books |plainurl=y |id=zcycBAAAQBAJ}}}} Tusks are slightly longer and thicker among males, which use them for fighting, dominance and display; the strongest males with the largest tusks typically dominate social groups. Tusks are also used to form and maintain holes in the ice and aid the walrus in climbing out of water onto ice.{{cite journal| vauthors = Fay FH |year = 1982|title = Ecology and Biology of the Pacific Walrus, Odobenus rosmarus divergens Illiger|journal= North American Fauna |volume=74 |pages=1–279 |doi=10.3996/nafa.74.0001|doi-access= free}} Tusks were once thought to be used to dig out prey from the seabed, but analyses of abrasion patterns on the tusks indicate they are dragged through the sediment while the upper edge of the snout is used for digging.{{cite journal| vauthors = Ray C, McCormick-Ray J, Berg P, Epstein HE |year = 2006|title = Pacific Walrus: Benthic bioturbator of Beringia|journal = Journal of Experimental Marine Biology and Ecology|pages = 403–419|doi = 10.1016/j.jembe.2005.12.043|volume = 330| issue=1 | bibcode=2006JEMBE.330..403R }} While the dentition of walruses is highly variable, they generally have relatively few teeth other than the tusks. The maximal number of teeth is 38 with dentition formula: {{DentalFormula|upper=3.1.4.2|lower=3.1.3.2}}, but over half of the teeth are rudimentary and occur with less than 50% frequency, such that a typical dentition includes only 18 teeth {{DentalFormula|upper=1.1.3.0|lower=0.1.3.0}}
=Vibrissae (whiskers)=
Surrounding the tusks is a broad mat of stiff bristles ("mystacial vibrissae"), giving the walrus a characteristic whiskered appearance. There can be 400 to 700 vibrissae in 13 to 15 rows reaching 30 cm (12 in) in length, though in the wild they are often worn to much shorter lengths due to constant use in foraging.{{cite journal |vauthors = Kastelein RA, Stevens S, Mosterd P |year = 1990 |title = The sensitivity of the vibrissae of a Pacific Walrus (Odobenus rosmarus divergens). Part 2: Masking |url = http://www.aquaticmammalsjournal.org/share/AquaticMammalsIssueArchives/1988/Aquatic_Mammals_14_3/Kastelein.pdf |journal = Aquatic Mammals |volume = 16 |issue = 2 |pages = 78–87 |access-date = 6 September 2017 |archive-date = 27 February 2020 |archive-url = https://web.archive.org/web/20200227015748/https://www.aquaticmammalsjournal.org/share/AquaticMammalsIssueArchives/1988/Aquatic_Mammals_14_3/Kastelein.pdf |url-status = dead }} The vibrissae are attached to muscles and are supplied with blood and nerves, making them highly sensitive organs capable of differentiating shapes {{convert|3|mm|in|frac=32|abbr=on}} thick and {{convert|2|mm|in|frac=32|abbr=on}} wide.
=Skin=
Aside from the vibrissae, the walrus is sparsely covered with fur and appears bald. Its skin is highly wrinkled and thick, up to {{convert|10|cm|in|0|abbr=on}} around the neck and shoulders of males. The blubber layer beneath is up to {{convert|15|cm|in|0|abbr=on}} thick. Young walruses are deep brown and grow paler and more cinnamon-colored as they age. Old males, in particular, become nearly pink. Because skin blood vessels constrict in cold water, the walrus can appear almost white when swimming. As a secondary sexual characteristic, males also acquire significant nodules, called "bosses", particularly around the neck and shoulders.
The walrus has an air sac under its throat which acts like a flotation bubble and allows it to bob vertically in the water and sleep. The males possess a large baculum (penis bone), up to {{convert|63|cm|in|abbr=on}} in length, the largest of any land mammal, both in absolute size and relative to body size.
Life history
=Reproduction=
Walruses live to about 20–30 years old in the wild.{{cite journal|vauthors = Fay FH|year = 1960|title = Carnivorous walrus and some arctic zoonoses|url = http://pubs.aina.ucalgary.ca/arctic/Arctic13-2-111.pdf|journal = Arctic|volume = 13|issue = 2|pages = 111–122|doi = 10.14430/arctic3691|access-date = 3 December 2010|archive-date = 9 August 2017|archive-url = https://web.archive.org/web/20170809040102/http://pubs.aina.ucalgary.ca/arctic/Arctic13-2-111.pdf|url-status = dead}} [http://pubs.aina.ucalgary.ca/arctic/Arctic14-1-76.pdf Comment] {{Webarchive|url=https://web.archive.org/web/20080409082148/http://pubs.aina.ucalgary.ca/arctic/Arctic14-1-76.pdf |date=9 April 2008 }} The males reach sexual maturity as early as seven years, but do not typically mate until fully developed at around 15 years of age. They rut from January through April, decreasing their food intake dramatically. The females begin ovulating as soon as four to six years old. The females are diestrous, coming into heat in late summer and around February, yet the males are fertile only around February; the potential fertility of this second period is unknown. Breeding occurs from January to March, peaking in February. Males aggregate in the water around ice-bound groups of estrous females and engage in competitive vocal displays.{{cite journal| vauthors = Nowicki SN, Stirling I, Sjare B |year = 1997|title = Duration of stereotypes underwater vocal displays by make Atlantic walruses in relation to aerobic dive limit|journal = Marine Mammal Science|volume = 13|issue = 4|pages = 566–575|doi = 10.1111/j.1748-7692.1997.tb00084.x| bibcode=1997MMamS..13..566N }} The females join them and copulate in the water.
File:Walrus - Kamogawa Seaworld - pup -1.jpg, Japan]]
Gestation lasts 15 to 16 months. The first three to four months are spent with the blastula in suspended development before it implants itself in the uterus. This strategy of delayed implantation, common among pinnipeds, presumably evolved to optimize both the mating season and the birthing season, determined by ecological conditions that promote newborn survival.{{cite journal | vauthors = Sandell M | title = The evolution of seasonal delayed implantation | journal = The Quarterly Review of Biology | volume = 65 | issue = 1 | pages = 23–42 | date = March 1990 | pmid = 2186428 | doi = 10.1086/416583 | s2cid = 35615292 }} Calves are born during the spring migration, from April to June. They weigh {{convert|45|to|75|kg|lb|abbr=on}} at birth and are able to swim. The mothers nurse for over a year before weaning, but the young can spend up to five years with the mothers. Walrus milk contains higher amounts of fats and protein compared to land animals but lower compared to phocid seals.{{cite book|last1=Riedman|first1=Marianne | name-list-style = vanc |title=The pinnipeds : seals, sea lions, and walruses|date=1990|publisher=University of California Press|location=Berkeley|isbn=978-0520064973|url={{google books |plainurl=y |id=McNEUgU8Q58C|page=281}}|pages=281–282}} This lower fat content in turn causes a slower growth rate among calves and a longer nursing investment for their mothers.{{cite book|editor-last1=Marsden|editor-first1=Terry|editor-last2=Murdoch|editor-first2=Jonathan | name-list-style = vanc |title=Current Topics in Developmental Biology, Volume 72.|date=2006|publisher=Elsevier|location=Burlington|isbn=978-0080463414|url={{google books |plainurl=y |id=rrRNK-i5yI0C|page=239}}|pages=277|edition=1st}} Young may be suckled at sea as well as during long haul-outs, making walrus the only pinnipeds that exhibit aquatic suckling.{{Cite book |last=Davis |first=Randall W. |title=Marine Mammals. Adaptations for an Aquatic Life |publisher=Springer |year=2019 |isbn=978-3319982786 |location=Berlin/Heidelberg |chapter=8.3 Lactation}} Because ovulation is suppressed until the calf is weaned, females give birth at most every two years, leaving the walrus with the lowest reproductive rate of any pinniped.{{cite book| veditors = Evans PG, Raga JA |year = 2001|title = Marine mammals: biology and conservation|location = London & New York|publisher = Springer|url={{google books |plainurl=y |id=riDDOeRd9JAC}}|isbn=978-0-306-46573-4}}
=Migration=
The rest of the year (late summer and fall), walruses tend to form massive aggregations of tens of thousands of individuals on rocky beaches or outcrops. The migration between the ice and the beach can be long-distance and dramatic. In late spring and summer, for example, several hundred thousand Pacific walruses migrate from the Bering Sea into the Chukchi Sea through the relatively narrow Bering Strait.{{cite book|last1=Fischbach|first1=Anthony S.|last2=Kochnev|first2=Anatoly A.|last3=Garlich-Miller|first3=Joel L.|last4=Jay|first4=Chadwick V. | name-list-style = vanc |title=Pacific Walrus Coastal Haulout Database, 1852–2016—Background Report|date=2016|publisher=U.S. Department of the Interior, U.S. Geological Survey|location=Reston, VA|url=https://purl.fdlp.gov/GPO/gpo70240|access-date=29 July 2016}}
Ecology
=Range and habitat=
The majority of the population of the Pacific walrus spends its summers north of the Bering Strait in the Chukchi Sea of the Arctic Ocean along the northern coast of eastern Siberia, around Wrangel Island, in the Beaufort Sea along the northern shore of Alaska south to Unimak Island,{{cite web|title=Izembek National Wildlife Report Sept 2015|url=http://www.aleutianseast.org/vertical/Sites/%7BEBDABE05-9D39-4ED4-98D4-908383A7714A%7D/uploads/Izembek_National_Wildlife_Refuge_Report_Sept_2015.pdf|publisher=USFWS|access-date=26 March 2017|archive-date=30 December 2016|archive-url=https://web.archive.org/web/20161230181745/http://www.aleutianseast.org/vertical/Sites/%7BEBDABE05-9D39-4ED4-98D4-908383A7714A%7D/uploads/Izembek_National_Wildlife_Refuge_Report_Sept_2015.pdf|url-status=dead}} and in the waters between those locations. Smaller numbers of males summer in the Gulf of Anadyr on the southern coast of the Siberian Chukchi Peninsula, and in Bristol Bay off the southern coast of Alaska, west of the Alaska Peninsula. In the spring and fall, walruses congregate throughout the Bering Strait, reaching from the western coast of Alaska to the Gulf of Anadyr. They winter over in the Bering Sea along the eastern coast of Siberia south to the northern part of the Kamchatka Peninsula, and along the southern coast of Alaska. A 28,000-year-old fossil walrus was dredged up from the bottom of San Francisco Bay, indicating that Pacific walruses ranged that far south during the last Ice Age.{{cite journal| vauthors = Dyke AS |year = 1999|title = The Late Wisconsinan and Holocene record of walrus (Odobenus rosmarus) from North America: A review with new data from Arctic and Atlantic Canada|journal = Arctic|volume = 52|issue = 2|pages = 160–181|doi=10.14430/arctic920|doi-access = free}}
File:Herd of Pacific walrus resting.png
Commercial harvesting reduced the population of the Pacific walrus to between 50,000 and 100,000 in the 1950s–1960s. Limits on commercial hunting allowed the population to increase to a peak in the 1970s-1980s, but subsequently, walrus numbers have again declined. Early aerial censuses of Pacific walrus conducted at five-year intervals between 1975 and 1985 estimated populations of above 220,000 in each of the three surveys.{{cite book | vauthors = Estes JA, Gol'tsev VN |title=Soviet American Cooperative Research on Marine Mammals | volume = 1 Pinnipeds |date=1984 |publisher=NOAA, Technical Report, NMFS 12 |pages=67–76 |chapter=Abundance and distribution of the Pacific walrus (Odobenus rosmarus divergens): results of the first Soviet American joint aerial survey, autumn 1975.}}{{cite journal | vauthors = Estes JA, Gilbert JR |title=Evaluation of an aerial survey of Pacific walruses (Odobenus rosmarus divergens). |journal=Journal of the Fisheries Research Board of Canada |volume=35 |issue=8 |pages=1130–1140 |date=1978|doi=10.1139/f78-178 }}{{cite book | vauthors = Gol'tsev VN |title=Aerial surveys of Pacific walruses in the Soviet sector during fall 1975 |date=1976 |publisher=Procedural Report TINRO |location=Magadan}}{{cite book | vauthors = Johnson A, Burns J, Dusenberry W, Jones R |title=Aerial survey of Pacific walruses, 1980. |date=1982 |publisher=U.S. Fish and Wildlife Service, Marine Mammals Management |location=Anchorage, Alaska}}{{cite book | vauthors = Fedoseev GA | veditors = Rodin VE, Perlov AS, Berzin AA, Gavrilov GM, Shevchenko AI, Fadeev NS, Kucheriavenko EB |title=Marine Mammals of the Far East |date=1984 |publisher=TINRO |location=Vladivostok |pages=73–85 |chapter=Present status of the population of walruses (Odobenus rosmarus) in the eastern Arctic and Bering Sea}}{{cite book | vauthors = Gilbert JR |title=Aerial survey of Pacific walruses in the Chukchi Sea, 1985 |date=1986 |publisher=Mimeo Report}}{{cite journal | vauthors = Gilbert JR |title=Aerial census of Pacific walruses in the Chukchi Sea, 1985 |journal=Marine Mammal Science |date=1989 |volume=5 |issue=1 |pages=17–28|doi=10.1111/j.1748-7692.1989.tb00211.x |bibcode=1989MMamS...5...17G }}{{cite journal | vauthors = Gilbert JR |title=Errata: Correction to the variance of products, estimates of Pacific walrus populations |journal=Marine Mammal Science |date=1989 |volume=5 |pages=411–412|doi=10.1111/j.1748-7692.1989.tb00356.x }}{{cite book | vauthors = Fedoseev GA, Razlivalov EV |title=The distribution and abundance of walruses in the eastern Arctic and Bering Sea in autumn 1985 |date=1986 |publisher=VNIRO |location=Magadan}}
In 2006, the population of the Pacific walrus was estimated to be around 129,000 on the basis of an aerial census combined with satellite tracking.{{cite journal|vauthors= Speckman SG, Chernook VI, Burn DM, Udevitz MS, Kochnev AA, Vasilev A, Jay CV, Lisovsky A, Fischbach AS, Benter RB|display-authors=etal|year=2010|title=Results and evaluation of a survey to estimate Pacific walrus population size, 2006|journal=Marine Mammal Science|volume=27|issue=3|pages=514–553|doi=10.1111/j.1748-7692.2010.00419.x}}{{cite web| author = US Fish and Wildlife Service| title = Stock Assessment Report: Pacific Walrus – Alaska Stock| year = 2014| url = https://www.fws.gov/r7/fisheries/mmm/stock/Revised_April_2014_Pacific_Walrus_SAR.pdf| access-date = 16 June 2019| archive-date = 18 February 2020| archive-url = https://web.archive.org/web/20200218015145/https://www.fws.gov/r7/fisheries/mmm/stock/Revised_April_2014_Pacific_Walrus_SAR.pdf| url-status = dead}} There were roughly 200,000 Pacific walruses in 1990.{{cite journal| vauthors = Gilbert JR |year = 1992|title = Aerial census of Pacific walrus, 1990|journal = USFWS R7/MMM Technical Report 92-1}}{{cite web|author= US Fish and Wildlife Service|title= Stock Assessment Report: Pacific Walrus – Alaska Stock|year= 2002|url= http://alaska.fws.gov/fisheries/mmm/walrus/pdf/Final_%20Pacific_Walrus_SAR.pdf|access-date= 3 October 2007|url-status= dead|archive-url= https://web.archive.org/web/20110515171808/http://alaska.fws.gov/fisheries/mmm/walrus/pdf/Final_%20Pacific_Walrus_SAR.pdf|archive-date= 15 May 2011}}
The much smaller population of Atlantic walruses ranges from the Canadian Arctic, across Greenland, Svalbard, and the western part of Arctic Russia. There are eight hypothetical subpopulations of Atlantic walruses, based largely on their geographical distribution and movements: five west of Greenland and three east of Greenland.{{cite journal| vauthors = Born E, Andersen L, Gjertz I, Wiig Ø |year = 2001|title = A review of the genetic relationships of Atlantic walrus (Odobenus rosmarus rosmarus) east and west of Greenland|journal = Polar Biology|volume = 24|pages = 713–718|doi = 10.1007/s003000100277|issue = 10| bibcode=2001PoBio..24..713E |s2cid = 191312}} The Atlantic walrus once ranged south to Sable Island, off of Nova Scotia; as late as the 18th century, they could be found in large numbers in the Greater Gulf of St. Lawrence region, sometimes in colonies of 7-8,000 individuals.{{cite book | last = Bolster | first = W. Jeffrey | name-list-style = vanc | title = The Mortal Sea: Fishing the Atlantic in the Age of Sail | location = Cambridge | publisher = Harvard University Press | date = 2012 }} This population was nearly eradicated by commercial harvest; their current numbers, though difficult to estimate, probably remain below 20,000.{{cite book | author = [NAMMCO] North Atlantic Marine Mammal Commission. | date = 1995 | title = Report of the third meeting of the Scientific Committee. | series = NAMMCO Annual Report 1995 | publisher = NAMMCO | location = Tromsø | pages = 71–127 }}{{cite web| author = North Atlantic Marine Mammal Commission| title = Status of Marine Mammals of the North Atlantic: The Atlantic Walrus| url = http://www.nammco.no/webcronize/images/Nammco/654.pdf| archive-url = https://wayback.archive-it.org/0/20071025220623/http://www.nammco.no/webcronize/images/Nammco/654.pdf| url-status = dead| archive-date = 25 October 2007| access-date = 3 October 2007| df = dmy-all}} In April 2006, the Canadian Species at Risk Act listed the populations of northwestern Atlantic walrus in Québec, New Brunswick, Nova Scotia, Newfoundland and Labrador as having been eradicated in Canada.{{cite web | author = Fisheries and Oceans Canada | title = Atlantic Walrus: Northwest Atlantic Population|access-date = 9 October 2007| url = http://www.dfo-mpo.gc.ca/species-especes/species/species_atlanticwalrus_e.asp | archive-url = https://web.archive.org/web/20070818123101/http://www.dfo-mpo.gc.ca/species-especes/species/species_atlanticwalrus_e.asp| archive-date = 18 August 2007}} A genetically distinct population existed in Iceland that was wiped out after Norse settlement around 1213–1330 AD.{{cite journal | vauthors = Keighley X, Pálsson S, Einarsson BF, Petersen A, Fernández-Coll M, Jordan P, Olsen MT, Malmquist HJ | display-authors = 6 | title = Disappearance of Icelandic Walruses Coincided with Norse Settlement | journal = Molecular Biology and Evolution | volume = 36 | issue = 12 | pages = 2656–2667 | date = December 2019 | pmid = 31513267 | pmc = 6878957 | doi = 10.1093/molbev/msz196 | url = }}
An isolated population is restricted, year-round, to the central and western regions of the Laptev Sea, from the eastern Kara Sea to the westernmost regions of the East Siberian Sea. The current population of these Laptev walruses has been estimated at between 5-10,000.{{cite web | title = Морж / Odobenus rosmarus | work = Ministry of Natural Resources of the Russian Federation protected species list | url = http://zapoved.ru/species/262/%D0%9C%D0%BE%D1%80%D0%B6 | archive-url = https://web.archive.org/web/20160304104207/http://zapoved.ru/species/262/%D0%9C%D0%BE%D1%80%D0%B6 | archive-date = 4 March 2016 | access-date = 4 October 2007 | url-status = live }}
Even though walruses can dive to depths beyond 500 meters, they spend most of their time in shallow waters (and the nearby ice floes) hunting for bivalves.{{cite web|url=https://arcticwwf.org/species/walrus/|title=Walrus Facts |website= World Wildlife Fund (WWF) }}{{cite journal | vauthors = Garde E, Jung-Madsen S, Ditlevsen S, Hansen RG, Zinglersen KB, Heide-Jørgensen MP | title = Diving behavior of the Atlantic walrus in high Arctic Greenland and Canada. | journal = Journal of Experimental Marine Biology and Ecology | date = March 2018 | volume = 500 | pages = 89–99 | doi = 10.1016/j.jembe.2017.12.009 | bibcode = 2018JEMBE.500...89G }}
In March 2021, a single walrus, nicknamed Wally the Walrus, was sighted at Valentia Island, Ireland, far south of its typical range, potentially due to having fallen asleep on an iceberg that then drifted south towards Ireland.{{cite web|title=First ever sighting of a walrus in Ireland after it is thought to have drifted across Atlantic after falling asleep on iceberg|url=https://www.independent.ie/news/first-ever-sighting-of-a-walrus-in-ireland-after-it-is-thought-to-have-drifted-across-atlantic-after-falling-asleep-on-iceberg-40195874.html|website=independent.ie| vauthors = Kelleher L, Palenque BK |date=14 March 2021|access-date=15 March 2021}} Days later, a walrus, thought to be the same animal, was spotted on the Pembrokeshire coast, Wales.{{cite web|title=Walrus spotted in Wales, days after one seen off Ireland|url=https://www.bbc.co.uk/news/uk-wales-56470235|website=bbc.co.uk|publisher=BBC News|date=20 March 2021|access-date=4 April 2021}}
In June 2022, a single walrus was sighted on the shores of the Baltic Sea - at Rügen Island, Germany, Mielno, Poland and Skälder Bay, Sweden.{{cite news | url=https://www.thelocal.de/20220617/walrus-makes-rare-stop-on-german-beach-to-delight-of-locals/ | title=Walrus makes rare stop on German beach to delight of locals | newspaper=The Local Germany | date=17 June 2022 }}{{cite web | url=https://notesfrompoland.com/2022/06/24/walrus-spotted-on-baltic-beach-in-first-ever-sighting-in-poland/ | title=Walrus spotted on Baltic beach in first ever sighting in Poland | date=24 June 2022 }}{{cite web | url=https://cde.news/photo-story-rare-visit-by-walrus-in-skane-sweden/ | title=Photo Story: Rare visit by Walrus in Skane, Sweden | date=12 June 2022 }} In July 2022, there was a report of a lost, starving walrus (nicknamed as Stena) in the coastal waters of the towns of Hamina and Kotka in Kymenlaakso, Finland,{{cite web|url=https://yle.fi/news/3-12538568|title=Visiting walrus causes stir in southern Finland town|work=Yle News|date=July 15, 2022|access-date=July 20, 2022}}{{cite web|url=https://nord.news/2022/07/18/the-walrus-destroyed-equipment-worth-more-than-10000-euros-says-a-kotka-fisherman/|title=The walrus destroyed equipment worth more than 10,000 euros, says a Kotka fisherman|work=Nord News|date=July 18, 2022|access-date=July 20, 2022}} that, despite rescue attempts, died of starvation when the rescuers tried to transport it to the Korkeasaari Zoo for treatment.{{cite news|url=https://euroweeklynews.com/2022/07/20/rare-walrus-hamina-finland/|title=UPDATE: Walrus found on the shore in Hamina, Finland has died, causing some outrage|first=Matthew|last=Roscoe|work=EuroWeekly News|date=July 20, 2022|access-date=July 20, 2022}}{{Cite web |date=2022-07-22 |title=Walrus' fate sparks online outrage |url=https://yle.fi/news/3-12546773 |access-date=2022-07-30 |website=Yle |language=en}}
=Diet=
File:Walrus - Kamogawa Seaworld - 1.jpg of a captive walrus (Japan)|alt=Photo of walrus head in profile showing one eye, nose, tusks, and "mustache"]]
Walruses prefer shallow shelf regions and forage primarily on the sea floor, often from sea ice platforms. They are not particularly deep divers compared to other pinnipeds; the deepest dives in a study of Atlantic walrus near Svalbard were only {{convert|31|±|17|m|abbr=on}}.{{cite journal| vauthors = Schreer JF, Kovacs KM, O'Hara Hines RJ |year = 2001|title = Comparative diving patterns of pinnipeds and seabirds|journal = Ecological Monographs|volume = 71|pages = 137–162|doi = 10.1890/0012-9615(2001)071[0137:CDPOPA]2.0.CO;2}} However, a more recent study recorded dives exceeding {{Convert|500|m|ft}} in Smith Sound, between NW Greenland and Arctic Canada – in general, peak dive depth can be expected to depend on prey distribution and seabed depth.
The walrus has a diverse and opportunistic diet, feeding on more than 60 genera of marine organisms, including shrimp, crabs, priapulids, spoon worms, tube worms, soft corals, tunicates, sea cucumbers, various mollusks (such as snails, octopuses, and squid), some types of slow-moving fish, and even parts of other pinnipeds.{{cite journal| vauthors = Sheffield G, Fay FH, Feder H, Kelly BP |year = 2001|title = Laboratory digestion of prey and interpretation of walrus stomach contents|journal = Marine Mammal Science|volume = 17| pages = 310–330|doi = 10.1111/j.1748-7692.2001.tb01273.x|issue = 2| bibcode=2001MMamS..17..310S }}[https://www.adfg.alaska.gov/static/home/library/pdfs/wildlife/research_pdfs/pacific_walrus_saint_lawrence_island_harvest_sample_analyses_2012_2014_2016.pdf Pacific Walrus (Odobenus rosmarus divergens) Saint Lawrence Island Harvest Sample Analyses, 2012–2014 and 2016] However, it prefers benthic bivalve mollusks, especially clams, for which it forages by grazing along the sea bottom, searching and identifying prey with its sensitive vibrissae and clearing the murky bottoms with jets of water and active flipper movements.{{cite journal | vauthors = Levermann N, Galatius A, Ehlme G, Rysgaard S, Born EW | title = Feeding behaviour of free-ranging walruses with notes on apparent dextrality of flipper use | journal = BMC Ecology | volume = 3 | issue = 9 | pages = 9 | date = October 2003 | pmid = 14572316 | pmc = 270045 | doi = 10.1186/1472-6785-3-9 | doi-access = free }} The walrus sucks the meat out by sealing its powerful lips to the organism and withdrawing its piston-like tongue rapidly into its mouth, creating a vacuum. The walrus palate is uniquely vaulted, enabling effective suction; researchers measured pressures in the oral cavity as low as -87.9 kPa in air, and -118.8 kPa underwater.{{cite journal|title=Oral suction of a Pacific walrus (Odobenus rosmarus divergens) in air and under water|vauthors = Kastelein RA, Muller M, Terlouw A |year=1994|pages=105-115|volume=59|journal=Zeitschrift für Säugetierkunde}} Walruses at the Tierpark Hagenbeck were easily able to suck the five-pound metal plug out of the bottom of their pool, at a water depth of 1.1 metres.{{cite journal|title=Notes on walruses (Odobenus rosmarus) in captivity|vauthors = Hagenbeck, CH |year=1962|pages=24-25|volume=4|journal=International Zoo Yearbook}} The diet of the Pacific walrus consist almost exclusively of benthic invertebrates (97 percent).{{cite book | chapter-url = {{google books |plainurl=y |id=6CE3AQAAMAAJ|page=SA4-PA277}} | chapter = Chapter 4.9.8.5: Other Pinnipeds | title = Alaska Groundfish Fisheries Final Programic Supplemental Environmental Impact Statement | work = Fishery Management Plans for the Groundfish Fishery of the Gulf of Alaska and the Groundfish of the Bering Sea and Aleutian Islands Area: Environmental Impact Statement |date=21 December 2018|via=Google Books}}
Aside from the large numbers of organisms actually consumed by the walrus, its foraging has a large peripheral impact on benthic communities. It disturbs (bioturbates) the sea floor, releasing nutrients into the water column, encouraging mixing and movement of many organisms and increasing the patchiness of the benthos.
Seal tissue has been observed in a fairly significant proportion of walrus stomachs in the Pacific, but the importance of seals in the walrus diet is under debate.{{cite book| vauthors = Lowry LF, Frost KJ |year = 1981|chapter = Feeding and Trophic Relationships of Phocid Seals and walruses in the Eastern Bering Sea|title = The Eastern Bering Sea Shelf: Oceanography & Resources vol. 2.|chapter-url={{google books |plainurl=y |id=DJwTAAAAYAAJ|page=813}}|editor1=National Ocean and Atmospheric Administration (NOAA) |publisher = University of Washington Press|pages = 813–824}} There have been isolated observations of walruses preying on seals up to the size of a {{convert|200|kg|lb|abbr=on}} bearded seal.{{cite journal|url=http://www.science.smith.edu/msi/pdf/i0076-3519-238-01-0001.pdf| vauthors = Fay FH | title=Odobenus rosmarus|journal=Mammalian Species|year=1985|pages=1–7|doi=10.2307/3503810|issue=238|jstor=3503810|url-status=dead|archive-url= https://web.archive.org/web/20130513012035/http://www.science.smith.edu/msi/pdf/i0076-3519-238-01-0001.pdf |archive-date=13 May 2013}}{{cite web|title= Photos from Trips to Pyramiden |url=http://www.spitsbergentravel.com/Start/About-Svalbard/Geography/Svalbard-Videos-Pyramiden/Photos-from-Pyramiden/ | archive-url = https://web.archive.org/web/20131203001719/http://www.spitsbergentravel.com/Start/About-Svalbard/Geography/Svalbard-Videos-Pyramiden/Photos-from-Pyramiden/ | archive-date = 3 December 2013 |publisher=Spitsbergen Online}} Rarely, incidents of walruses preying on seabirds, particularly the Brünnich's guillemot (Uria lomvia), have been documented.{{cite journal| vauthors = Mallory ML, Woo K, Gaston A, Davies WE, Mineau P |year = 2004|title = Walrus (Odobenus rosmarus) predation on adult thick-billed murres (Uria lomvia) at Coats Island, Nunavut, Canada|journal = Polar Research|volume = 23|issue = 1|pages = 111–114|doi = 10.1111/j.1751-8369.2004.tb00133.x| doi-broken-date=2 November 2024 |bibcode = 2004PolRe..23..111M}} Walruses may occasionally prey on ice-entrapped narwhals and scavenge on whale carcasses but there is little evidence to prove this.{{cite magazine|title=Narwhals, Narwhal Pictures, Narwhal Facts|url=http://animals.nationalgeographic.com/animals/mammals/narwhal/|archive-url=https://web.archive.org/web/20100112221908/http://animals.nationalgeographic.com/animals/mammals/narwhal/|url-status=dead|archive-date=12 January 2010|magazine=National Geographic|date=11 November 2010}}{{cite web|title=Walrus facts|url=http://www.canadiangeographic.ca/article/animal-facts-walrus|publisher=Canadian Geographic|access-date=20 August 2016|date=2016-04-04}}
=Predators=
Due to its great size and tusks, the walrus has only two natural predators: the orca and the polar bear.{{cite web| author = Mr. Appliance |title=Walrus Predators|url=http://www.walrus-world.com/walrus-predators.html|access-date=10 November 2012|archive-url=https://web.archive.org/web/20130126224852/http://www.walrus-world.com/walrus-predators.html|archive-date=26 January 2013|url-status=dead}} The walrus does not, however, comprise a significant component of either of these predators' diets. Both the orca and the polar bear are also most likely to prey on walrus calves. The polar bear often hunts the walrus by rushing at beached aggregations and consuming the individuals crushed or wounded in the sudden exodus, typically younger or infirm animals.{{cite journal| vauthors = Ovsyanikov N |year = 1992|title = Ursus ubiquitous|journal = BBC Wildlife|volume = 10|issue = 12|pages = 18–26}} The bears also isolate walruses when they overwinter and are unable to escape a charging bear due to inaccessible diving holes in the ice.{{cite journal|jstor=3872939|title=Interactions between Polar Bears and Overwintering Walruses in the Central Canadian High Arctic| vauthors = Calvert W, Stirling I |year=1990|pages=351–356|volume=8|journal=Bears: Their Biology and Management |doi=10.2307/3872939 |s2cid=134001816}} However, even an injured walrus is a formidable opponent for a polar bear, and direct attacks are rare. Armed with its ivory tusks, walruses have been known to fatally injure polar bears in battles if the latter follows the other into the water, where the bear is at a disadvantage.{{cite web|title=North American Bear Center – Polar Bear Facts|url=http://www.bear.org/website/bear-pages/polar-bear/22-/70-polar-bear-facts.html|publisher=North American Bear Center|access-date=2 August 2013|archive-url=https://web.archive.org/web/20130524061813/http://www.bear.org/website/bear-pages/polar-bear/22-/70-polar-bear-facts.html|archive-date=24 May 2013|url-status=dead|df=dmy-all}} Polar bear–walrus battles are often extremely protracted and exhausting, and bears have been known to break away from the attack after injuring a walrus. Orcas regularly attack walruses, although walruses are believed to have successfully defended themselves via counterattack against the larger cetacean.{{cite journal | vauthors = Jefferson TA, Stacey PJ, Baird RW |title=A review of Killer Whale interactions with other marine mammals: Predation to co-existence |year=1991 |journal=Mammal Review|volume=21|issue=4|page=151 |doi=10.1111/j.1365-2907.1991.tb00291.x |url=http://www.cascadiaresearch.org/robin/kwinteractionsrev.pdf }} However, orcas have been observed successfully attacking walruses with few or no injuries.{{cite journal | vauthors = Kryukova NV, Kruchenkova EP, Ivanov DI |title=Killer whales (Orcinus orca) hunting for walruses (Odobenus rosmarus divergens) near Retkyn Spit, Chukotka|year=2012 |journal=Biology Bulletin|volume=39|issue=9|pages=768–778 |doi=10.1134/S106235901209004X |bibcode=2012BioBu..39..768K |s2cid=16477223}}
Relationship with humans
=Conservation=
In the 18th and 19th centuries, the walrus was heavily exploited by American and European sealers and whalers, leading to the near-extinction of the Atlantic subspecies.{{cite journal| vauthors = Bockstoce JR, Botkin DB |year = 1982|title = The Harvest of Pacific Walruses by the Pelagic Whaling Industry, 1848 to 1914|journal = Arctic and Alpine Research|volume = 14|issue = 3|pages = 183–188|doi = 10.2307/1551150|jstor = 1551150}} As early as 1871 traditional hunters were expressing concern about the numbers of walrus being hunted by whaling fleets.{{Cite news |last=Humanities |first=National Endowment for the |date=1871-09-27 |title=The Hawaiian gazette. [volume] (Honolulu [Oahu, Hawaii]) 1865-1918, September 27, 1871, Image 2 |url=https://chroniclingamerica.loc.gov/lccn/sn83025121/1871-09-27/ed-1/seq-2/ |access-date=2022-11-27 |issn=2157-1392}} Commercial walrus harvesting is now outlawed throughout its range, although Chukchi, Yupik and Inuit peoples{{cite web| vauthors = Chivers CJ |date = 25 August 2002|url = https://www.nytimes.com/2002/08/25/magazine/a-big-game.html|title = A Big Game|work = The New York Times |access-date = March 30, 2022|archive-url = https://web.archive.org/web/20220120162346/http://www.nytimes.com/2002/08/25/magazine/a-big-game.html|archive-date =January 20, 2022|df = dmy-all}} are permitted to kill small numbers towards the end of each summer.
Traditional hunters used all parts of the walrus.{{cite web|author=US Fish and Wildlife Service|title=Hunting and Use of Walrus by Alaska Natives|year=2007|url=http://alaska.fws.gov/fisheries/mmm/mtrp/pdf/factsheet_walrus.pdf|access-date=9 October 2007|url-status=dead|archive-url=https://web.archive.org/web/20110515172040/http://alaska.fws.gov/fisheries/mmm/mtrp/pdf/factsheet_walrus.pdf|archive-date=15 May 2011}} The meat, often preserved, is an important winter nutrition source; the flippers are fermented and stored as a delicacy until spring; tusks and bone were historically used for tools, as well as material for handicrafts; the oil was rendered for warmth and light; the tough hide made rope and house and boat coverings; and the intestines and gut linings made waterproof parkas. While some of these uses have faded with access to alternative technologies, walrus meat remains an important part of local diets,{{cite journal| vauthors = Eleanor EW, Freeman MM, Makus JC |year = 1996|title = Use and preference for Traditional Foods among Belcher Island Inuit|jstor=40512002|doi=10.14430/arctic1201|journal = Arctic|volume = 49|issue = 3|pages = 256–264|s2cid = 53985170|doi-access = free}} and tusk carving and engraving remain a vital art form.
According to Adolf Erik Nordenskiöld, European hunters and Arctic explorers found walrus meat not particularly tasty, and only ate it in case of necessity; however walrus tongue was a delicacy.{{cite book | first = Adolf Erik | last = Nordenskiöld | translator-first = Alexander | translator-last = Leslie | name-list-style = vanc | publisher = Macmillan and Company | year = 1882 | title = The Voyage of the Vega Round Asia and Europe: With a Historical Review of Previous Journeys Along the North Coast of the Old World Collection Léo Pariseau | url = {{google books |plainurl=y |id=Y-bMaEoOGWAC|page=122}} | page = 122 }}
File:Pacific Walrus - Bull (8247646168).jpg|Male Pacific Walrus, Alaska
File:Walrus hunter 1911.jpg|Hunter sitting on dozens of walruses killed for their tusks, 1911
File:PolarBearWalrusTuskCarving.jpg|alt=Photo of section of tusk|Walrus tusk scrimshaw made by Chukchi artisans depicting polar bears attacking walruses, on display in the Magadan Regional Museum, Magadan, Russia
File:Valrossarna på Skansen matas av djurskötare och herre i paletå och hög hatt - Nordiska Museet - NMA.0048348.jpg|Walrus being fed at Skansen in Stockholm, Sweden, 1908
File:Eskimo woman dressing walrus skin, Alaska, nd (COBB 273).jpeg|Native Alaskan woman dresses walrus skin
Walrus hunts are regulated by resource managers in Russia, the United States, Canada, and Greenland, and by representatives of the respective hunting communities. An estimated four to seven thousand Pacific walruses are harvested in Alaska and in Russia, including a significant portion (about 42%) of struck and lost animals.{{cite journal|journal = Fishery Bulletin| vauthors = Garlich-Miller JG, Burn DM |year = 1997|title = Estimating the harvest of Pacific walrus, Odobenus rosmarus divergens, in Alaska|volume = 97|issue = 4|pages = 1043–1046|url=https://www.researchgate.net/publication/228991487}} Several hundred are removed annually around Greenland.{{cite journal| vauthors = Witting L, Born EW |year = 2005|title = An assessment of Greenland walrus populations|journal = ICES Journal of Marine Science|volume = 62|issue = 2|pages = 266–284|doi = 10.1016/j.icesjms.2004.11.001|doi-access = free| bibcode=2005ICJMS..62..266W }} The sustainability of these levels of harvest is difficult to determine given uncertain population estimates and parameters such as fecundity and mortality. The Boone and Crockett Big Game Record book has entries for Atlantic and Pacific walrus. The recorded largest tusks are just over 30 inches and 37 inches long respectively.{{cite web | url = https://www.boone-crockett.org/bc-worlds-record-atlantic-walrus | work = Boone and Crockett Club | title = B&C World's Record - Atlantic Walrus | date = 29 October 2016 | access-date = 30 March 2022}}
The effects of global climate change are another element of concern. The extent and thickness of the pack ice has reached unusually low levels in several recent years. The walrus relies on this ice while giving birth and aggregating in the reproductive period. Thinner pack ice over the Bering Sea has reduced the amount of resting habitat near optimal feeding grounds. This more widely separates lactating females from their calves, increasing nutritional stress for the young and lower reproductive rates.{{cite news | vauthors = Kaufman M |title = Warming Arctic Is Taking a Toll, Peril to Walrus Young Seen as Result of Melting Ice Shelf|url =https://www.washingtonpost.com/archive/politics/2006/04/15/warming-arctic-is-taking-a-toll-span-classbankheadperil-to-walrus-young-seen-as-result-of-melting-ice-shelf-span/de231f8a-0e52-48e8-8477-7c939b14c0dd/|newspaper = The Washington Post|page = A7|date = 15 April 2006|access-date=30 March 2022}} Reduced coastal sea ice has also been implicated in the increase of stampeding deaths crowding the shorelines of the Chukchi Sea between eastern Russia and western Alaska.{{cite web | last = Revkin | first = Andrew C. | name-list-style = vanc | date = 2 October 2009 | url = https://www.nytimes.com/2009/10/03/science/earth/03walrus.html?ref=todayspaper | title = Global warming could reverse a walrus comeback | work = The New York Times | access-date = 16 September 2011 }}{{cite web | first = Nick | last = Sundt | name-list-style = vanc | title = As Arctic Sea ice reaches annual minimum, large number of walrus corpses found | url = http://wwfblogs.org/climate/content/arctic-sea-ice-reaches-annual-minimum-large-number-walrus-corpses-found-along-alaska-shoreli | work = World Wildlife Fund | archive-url = https://web.archive.org/web/20090924005822/http://wwfblogs.org/climate/content/arctic-sea-ice-reaches-annual-minimum-large-number-walrus-corpses-found-along-alaska-shoreli | archive-date=24 September 2009 | date = 18 September 2009 | access-date = 16 September 2011 }} Analysis of trends in ice cover published in 2012 indicate that Pacific walrus populations are likely to continue to decline for the foreseeable future, and shift further north, but that careful conservation management might be able to limit these effects.{{cite journal | vauthors = Maccracken JG | title = Pacific Walrus and climate change: observations and predictions | journal = Ecology and Evolution | volume = 2 | issue = 8 | pages = 2072–90 | date = August 2012 | pmid = 22957206 | doi = 10.1002/ece3.317 | pmc = 3434008 | doi-access = free | bibcode = 2012EcoEv...2.2072M }}
Currently, two of the three walrus subspecies are listed as "least-concern" by the IUCN, while the third is "data deficient". The Pacific walrus is not listed as "depleted" according to the Marine Mammal Protection Act nor as "threatened" or "endangered" under the Endangered Species Act. The Russian Atlantic and Laptev Sea populations are classified as Category 2 (decreasing) and Category 3 (rare) in the Russian Red Book. Global trade in walrus ivory is restricted according to a CITES Appendix 3 listing. In October 2017, the Center for Biological Diversity announced they would sue the U.S. Fish and Wildlife Service to force it to classify the Pacific Walrus as a threatened or endangered species.{{cite news | first = Dan | last = Joling | name-list-style = vanc |url=http://www.mercurynews.com/2017/10/12/group-plans-to-sue-over-walrus-protection/|title=Group plans to sue over walrus protection|date=12 October 2017|work=The Mercury News|access-date=12 October 2017|language=en-US}}
In 1952, walruses in Svalbard were nearly gone due to ivory hunting over a 300 years period, but the Norwegian government banned their commercial hunting and the walruses began to repopulate. By 2018, the population had increased to an estimated 5,503 walruses in the Svalbard area.{{Cite web |last=Kubny |first=Heiner |title=Hunting ban helped the walrus on Svalbard |url=https://polarjournal.ch/en/2022/04/07/hunting-ban-helped-the-walrus-on-svalbard/ |access-date=2024-01-29 |website=Polar Journal |language=en-US |archive-date=29 January 2024 |archive-url=https://web.archive.org/web/20240129192528/https://polarjournal.ch/en/2022/04/07/hunting-ban-helped-the-walrus-on-svalbard/ |url-status=dead }}
=Culture=
==Folklore==
The walrus plays an important role in the religion and folklore of many Arctic peoples. Skin and bone are used in some ceremonies, and the animal appears frequently in legends. For example, in a Chukchi version of the widespread myth of the Raven, in which Raven recovers the sun and the moon from an evil spirit by seducing his daughter, the angry father throws the daughter from a high cliff and, as she drops into the water, she turns into a walrus . According to various legends, the tusks are formed either by the trails of mucus from the weeping girl or her long braids.{{cite journal| vauthors = Bogoras W |year= 1902|title= The Folklore of Northeastern Asia, as Compared with That of Northwestern America|journal=American Anthropologist|volume=4|issue=4|pages=577–683|doi=10.1525/aa.1902.4.4.02a00020|doi-access=free}} This myth is possibly related to the Chukchi myth of the old walrus-headed woman who rules the bottom of the sea, who is in turn linked to the Inuit goddess Sedna. Both in Chukotka and Alaska, the aurora borealis is believed to be a special world inhabited by those who died by violence, the changing rays representing deceased souls playing ball with a walrus head.{{cite journal | vauthors = Boas F | year = 1901 | title = The Eskimo of Baffin Land and Hudson Bay | journal = Bulletin of the American Museum of Natural History | volume = 15 | url = {{google books |plainurl=y |id=FOkiAQAAMAAJ|page=146}} | page = 146 }}
File:Ivorymasks.jpg|alt=Photo of two masks: In the center is the image of a face, surrounded by a ring, in turn surrounded by eight white rectangular pieces.|Walrus ivory masks made by Yupik in Alaska
File:Briny Beach.jpg|alt=Drawing of walrus, and square-headed men, both perched on rocks, with ocean and cliffs in background|John Tenniel's illustration for Lewis Carroll's poem "The Walrus and the Carpenter"
File:Hugo-de-Groot-Nederlandtsche-jaerboeken MG 0188.tif|Dutch explorers fight a walrus on the coast of Novaya Zemlya, 1596
Most of the distinctive 12th-century Lewis Chessmen from northern Europe are carved from walrus ivory, though a few have been found to be made of whales' teeth.
==Literature==
Because of its distinctive appearance, great bulk, and immediately recognizable whiskers and tusks, the walrus also appears in the popular cultures of peoples with little direct experience with the animal, particularly in English children's literature. Perhaps its best-known appearance is in Lewis Carroll's whimsical poem "The Walrus and the Carpenter" that appears in his 1871 book Through the Looking-Glass. In the poem, the eponymous antiheroes use trickery to consume a great number of oysters. Although Carroll accurately portrays the biological walrus's appetite for bivalve mollusks, oysters, primarily nearshore and intertidal inhabitants, these organisms in fact comprise an insignificant portion of its diet in captivity.{{cite journal | vauthors = Kastelein RA, Wiepkema PR, Slegtenhorst C | year = 1989 | title = The use of molluscs to occupy Pacific walrusses (Odobenus rosmarus divergens) in human care | journal = Aquatic Mammals | volume = 15 | issue = 1 | pages = 6–8 | url = http://www.aquaticmammalsjournal.org/share/AquaticMammalsIssueArchives/1989/Aquatic_Mammals_15_1/Kastelein_Wiepkema_Slegtenhorst.pdf | access-date = 9 October 2011 | archive-date = 29 February 2020 | archive-url = https://web.archive.org/web/20200229232717/https://www.aquaticmammalsjournal.org/share/AquaticMammalsIssueArchives/1989/Aquatic_Mammals_15_1/Kastelein_Wiepkema_Slegtenhorst.pdf | url-status = dead }}
The "walrus" in the cryptic song "I Am the Walrus" by the Beatles is a reference to the Lewis Carroll poem.{{cite web |last=Zimmer |first=Ben | name-list-style = vanc |title=The Delights of Parsing the Beatles' Most Nonsensical Song |url=https://www.theatlantic.com/entertainment/archive/2017/11/i-am-the-walrus-50-years-later/546698/ |date=2017-11-24|website=The Atlantic|language=en-US|access-date=2019-03-18}}
Another appearance of the walrus in literature is in the story "The White Seal" in Rudyard Kipling's The Jungle Book, where it is the "old Sea Vitch—the big, ugly, bloated, pimpled, fat-necked, long-tusked walrus of the North Pacific, who has no manners except when he is asleep".{{cite book | last = Kipling | first = Rudyard | name-list-style = vanc | orig-year = 1894 | title = The Jungle Book | date = 1994 | location = Harmondsworth, England | publisher = Penguin Popular Classics | page = 84 | isbn = 0-14-062104-0 }}
See also
References
{{Reflist}}
Further reading
{{Refbegin}}
- {{cite book | vauthors = Heptner VG, Nasimovich AA, Bannikov AG, Hoffmann RS | url = https://archive.org/details/mammalsofsov231996gept | title = Mammals of the Soviet Union | volume = 2 part 3 | location = Washington, D.C. | publisher = Smithsonian Institution Libraries and National Science Foundation | date = 1996 }}
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External links
{{Wiktionary|walrus}}
{{EB1911 poster|Walrus}}
- {{Wikispecies-inline|Odobenus rosmarus}}
- {{Commons category-inline|Odobenus rosmarus}}
- [https://www.npr.org/templates/story/story.php?storyId=130083334&sc=fb&cc=fp Biologist Tracks Walruses Forced Ashore As Ice Melts] – audio report by NPR
- [http://www.huffingtonpost.com/2010/09/30/tens-of-thousands-of-walr_n_744366.html?view=print Thousands Of Walruses Crowd Ashore Due To Melting Sea Ice] – video by National Geographic
- [http://cetus.ucsd.edu/voicesinthesea_org/species/pinnipeds/pacificWalrus.html Voices in the Sea – Sounds of the Walrus]. {{Webarchive|url=https://web.archive.org/web/20140709001938/http://cetus.ucsd.edu/voicesinthesea_org/species/pinnipeds/pacificWalrus.html |date=9 July 2014 }}.
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{{Pan-Pinnipedia|O.|state=autocollapse}}
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Category:Pinnipeds of the Arctic Ocean
Category:Mammals described in 1758
Category:Pinnipeds of North America
Category:Mammals of the United States