Erignathus barbatus: Diferenzas entre revisións
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Como moitos mamíferos do Ártico, empregan unha estratexia reprodutora denominada [[implantación retardada]], que consiste en que o [[blastocisto]] tarda dous meses en implantarse despois da fecundación, implantándose xeralmente en xullo. Así, o período de [[xestación]] total da foca é duns once meses, aínda que a súa xestación activa é de nove meses.<ref>{{cite book | author = Perry, Judith E. | title = Seals of the World | publisher = Comstock Publishing Associates | location = Ithaca, NY | year = 1983 | page = 103}}</ref>
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Natural predators of the bearded seal include polar bears, who rely on these seals as a major food source.<ref name="Bearded seal">{{cite web|title=Erignathus barbatus – bearded seal|url=http://animaldiversity.ummz.umich.edu/accounts/Erignathus_barbatus/|publisher=Animal Diversity Web}}</ref> [[Killer whale]]s also prey on these seals, sometimes overturning ice floes to reach them. [[Walrus]]es also eat these seals, mainly pups, but such predation is rare.<ref>Folkens, Peter (2002). ''National Audubon Society Guide to Marine Mammals of the World.'' New York, pg. 117.</ref>▼
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Bearded seals are believed to live up to 31 years.<ref>National Marine Mammal Laboratory [http://www.afsc.noaa.gov/nmml/education/pinnipeds/bearded.php#die Bearded Seals] Retrieved May 1, 2016</ref>▼
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== Vocalización ==
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The vocalizations produced by the bearded seal are very unique, possibly because their [[trachea]] is different from that of other Northern Pacific [[Earless seal|phocids]]. A majority of the rings in the trachea are incomplete with only a membrane attaching the two ends.<ref name=":2">{{Cite web|url=https://www.boem.gov/ESPIS/0/312.pdf|title=Natural History and Ecology of the Bearded Seal, Erignathus Barbatus|last=Burns|first=John J.|date=May 1979|website=|access-date=}}</ref>[[File:Svalbard_Sample_for_Wiki.ogg|thumb|Sample of underwater bearded seal vocalizations taken using a hydrophone.]]The sounds of the bearded seal usually consist of a long [[Oscillation|oscillating]] trill lasting for a minute or more followed by a short, deep moan. This 'song' is often repeated frequently.<ref name=":2" /> The number of call types within a population can vary geographically, with four types found in Svalbard and eleven in the Western Canadian Arctic. The most frequent sounds are trills, moans, and sweeps. A sweep can be compared to a short trill.<ref name=":0">{{Cite journal|last=Risch|first=Denise|last2=Clark|first2=Christopher W.|last3=Corkeron|first3=Peter J.|last4=Elepfandt|first4=Andreas|last5=Kovacs|first5=Kit M.|last6=Lydersen|first6=Christian|last7=Stirling|first7=Ian|last8=Van Parijs|first8=Sofie M.|date=May 2007|title=Vocalizations of male bearded seals, Erignathus barbatus: classification and geographical variation|journal=Animal Behaviour|volume=73|issue=5|pages=747–762|doi=10.1016/j.anbehav.2006.06.012|issn=0003-3472}}</ref>
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