Vagrant Antarctic pinnipeds at Gough Island

Wilson, John W.; Burle, M.-H.; Bester, Marthán N

doi:10.1007/s00300-006-0187-5

Cited by 14 publications

(7 citation statements)

References 9 publications

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“…Other explanations for the rarity of Pelagiarctos within the Round Mountain Silt also exist. Many seals are prone to vagrancy [71]–[74], and the rarity of an individual taxon within a specific formation may reflect only occasional occurrence within the given region. In addition, the Sharktooth Hill bonebed was formed over a protracted period of time, possibly as long as 700 ka [75].…”

Section: Discussionmentioning

confidence: 99%

A Reevaluation of the Morphology, Paleoecology, and Phylogenetic Relationships of the Enigmatic Walrus Pelagiarctos

Boessenecker

Churchill

2013

PLoS ONE

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BackgroundA number of aberrant walruses (Odobenidae) have been described from the Neogene of the North Pacific, including specialized suction-feeding and generalist fish-eating taxa. At least one of these fossil walruses has been hypothesized to have been a specialized predator of other marine mammals, the middle Miocene walrus Pelagiarctos thomasi from the Sharktooth Hill Bonebed of California (16.1–14.5 Ma).Methodology/Principal FindingsA new specimen of Pelagiarctos from the middle Miocene “Topanga” Formation of southern California (17.5–15 Ma) allows a reassessment of the morphology and feeding ecology of this extinct walrus. The mandibles of this new specimen are robust with large canines, bulbous premolars with prominent paraconid, metaconid, hypoconid cusps, crenulated lingual cingula with small talonid basins, M2 present, double-rooted P3–M1, single-rooted P1 and M2, and a P2 with a bilobate root. Because this specimen lacks a fused mandibular symphysis like Pelagiarctos thomasi, it is instead referred to Pelagiarctos sp. This specimen is more informative than the fragmentary holotype of Pelagiarctos thomasi, permitting Pelagiarctos to be included within a phylogenetic analysis for the first time. Analysis of a matrix composed of 90 cranial, dental, mandibular and postcranial characters indicates that Pelagiarctos is an early diverging walrus and sister to the late Miocene walrus Imagotaria downsi. We reevaluate the evidence for a macropredatory lifestyle for Pelagiarctos, and we find no evidence of specialization towards a macrophagous diet, suggesting that Pelagiarctos was a generalist feeder with the ability to feed on large prey.Conclusions/SignificanceThis new specimen of Pelagiarctos adds to the knowledge of this problematic taxon. The phylogenetic analysis conclusively demonstrates that Pelagiarctos is an early diverging walrus. Pelagiarctos does not show morphological specializations associated with macrophagy, and was likely a generalist predator, feeding on fish, invertebrates, and the occasional warm-blooded prey item.

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Section: Discussionmentioning

confidence: 99%

A Reevaluation of the Morphology, Paleoecology, and Phylogenetic Relationships of the Enigmatic Walrus Pelagiarctos

Boessenecker

Churchill

2013

PLoS ONE

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“…Both fur seals have similar annual cycles, diVering mainly in the duration of lactation (4 months and 10-11 months in Antarctic fur seals and Subantarctic fur seals, respectively) and median birthdates (6 December and 10 December, respectively) at sites in the Southern Atlantic Ocean 1987;Bester 1987). Where they breed in sympatry at, for example, Marion Island, the two species thrive and hybridize to an extent (Condy 1978;Hofmeyr et al 2006); development of a similar situation at Gough Island would compromise the 'pure' genetic status of the Subantarctic fur seal population there (Wynen et al 2000;Wilson et al 2006). The re-appearance of Antarctic fur seals at Gough Island, their presence on the same beaches as in October 2005 (Seal Beach and Wild Glen) or perhaps their continued presence there (any individuals present might have been overlooked due to incomplete searching of beaches by inexperienced personnel in the intervening years), suggests a more frequent association with the island.…”

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confidence: 99%

“…However, Gough Island is the northernmost island record of vagrant Antarctic fur seals which required open ocean navigation all the way . Such records might indicate that A. gazella disperse from their natal breeding localities as populations recover after large-scale harvesting of the nineteen and early twentieth century ceased and congested conditions develop (McCann and Doidge 1987;Hofmeyr et al 2005;Wilson et al 2006).…”

mentioning

confidence: 99%

Vagrant Antarctic fur seals at Gough Island in 2009

Bester

Reisinger

2009

Polar Biol

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The Antarctic fur seal Arctocephalus gazella at Gough Island (40°20ЈS, 09°54ЈW) in the South Atlantic Ocean, Wrst seen in October/November 2005, was recorded again in September-October 2009. Up to three diVerent individual Antarctic fur seals were sighted on a single day, on a particular beach. A total of seven diVerent individuals were recorded over a 3-week period, well before the onset of the breeding (pupping) season of the resident population of Subantarctic fur seals A. tropicalis. Positively identiWed individuals were all male, mostly subadult and lean. Only a fraction (»20%) of the available beaches was searched, and it is unknown if the Antarctic fur seals were still present at Gough Island during the austral summer breeding season of southern fur seals.

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“…2b). Despite the 5day lapse between the sightings at TdC and 380 km distant Gough Island (GI), where it was seen in the same area as previous sightings (Wilson et al 2006;Bester and Reisinger 2010), it is impossible to say whether it is the same animal.…”

mentioning

confidence: 98%

“…Moreover, the poor body condition and general lethargy of the individuals likely indicate that they are vagrants that made a fortuitous landfall to rest outside of their usual foraging range (Wilson et al 2006;Bester and Reisinger 2010;this study). Vagrant A. gazella have been recorded at a number of localities around the Southern Ocean (Acevedo et al 2011), but the Tristan sighting represents the northernmost oceanic island record for the species, although more northerly records (33˚08'S) of this species from mainland Brazil (Cherem et al 2004) exist.…”

mentioning

confidence: 98%