Diferenzas entre revisións de «Erignathus barbatus»

== Vocalización ==
[[Ficheiro:Svalbard_Sample_for_Wiki.ogg|miniatura|Mostra das vocalizacións da foca barbuda gravadas cun hidrófono.]]
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>
Bearded seals produce distinct trills from late March to late June, with a decline in [[rhythm]]icity in late May and June. This timeline coincides with their breeding and pupping season, which is from April to May. The repetitive and transmittable nature of bearded seal trills leads researchers to believe that they are utilized for communication, likely during [[Courtship display|courtship]] and breeding.<ref name=":1">{{Cite journal|last=Cleator|first=Holly J.|last2=Stirling|first2=Ian|last3=Smith|first3=T. G.|date=5 July 1989|title=Underwater vocalizations of the bearded seal (Erignathus barbatus)|journal=Canadian Journal of Zoology|volume=67|issue=8|pages=1900–1910|doi=10.1139/z89-272|issn=0008-4301}}</ref> Males use these sounds to establish mating territories and communicate their fitness,<ref name=":0" /> but it is likely that females produce these sounds as well.<ref name=":1" />
Underwater, bearded seal trills can be heard from a distance of over 30&nbsp;km, with some types of sounds traveling farther than others. This makes it possible for one animal to communicate with another animal that is far away, although acoustic degradation does occur as the sound passes through the environment. A seal must produce a trill with a [[Sound pressure|sound-pressure]] of at least 100 [[Decibel|dB]] at 1 m in order for the sound to propagate 30&nbsp;km, meaning that bearded seals can likely produce sounds at this level.<ref name=":1" />[[Image:beardedseal2.jpg|thumb|Bearded seal on ice, [[Svalbard]]]]
[[Ficheiro:beardedseal2.jpg|miniatura|Foca barbuda sobre o xeo en [[Svalbard]]]]
== Status de conservación ==
A [[IUCN]] clasifica esta especie como en situación "pouco preocupante".<ref>{{Cite web|url=http://oldredlist.iucnredlist.org/details/8010/0|title=Erignathus barbatus (Bearded Seal)|website=www.iucnredlist.org|access-date=2018-06-06}}</ref> Esta clasificación está determinada por varios factores como a súa ampla distribución, tamaño de poboación estable, e recursos de posibles presas alternativos. A [[NOAA]] determinou que os factores que inflúen en calquera posible cambio no status de conservación da foca barbuda poden ser: perda de xeo mariño por mor do cambio climático, pesca accidental (''bycatch'') en aparellos de pesca comerciais e a caza.<ref>{{Cite web|url=https://www.fisheries.noaa.gov/species/bearded-seal|title=Bearded Seal {{!}} NOAA Fisheries|last=Fisheries|first=NOAA|date=2018-05-24|website=www.fisheries.noaa.gov|language=EN-US|access-date=2018-06-06}}</ref> Os seus principais depredadores son os osos polares.<ref>{{Cite journal|title=Canadian Science Publishing|url=http://www.nrcresearchpress.com/doi/abs/10.1139/z80-302#.Ww96nkgvzIU|doi=10.1139/z80-302#.ww96nkgvziu|doi-broken-date=2019-03-13}}</ref> Debido ao cambio climático, os factores como a perda de xeo mariño ou a diminución das poboacións de presas poden producir resultados negativos sobre as poboacións da foca barbuda no futuro. Por tanto, a monitorización da especie e as influencias das actividades humanas serán vitais para asegurar a estabilidade da especie.