Hybridisation between South polar skua (Catharacta maccormicki) and Brown skua (C. antarctica lonnbergi) in the Antarctic Peninsula region

Ritz, Markus S.; Hahn, Steffen; Janicke, Tim; Peter, Hans‐Ulrich

doi:10.1007/s00300-005-0034-0

Cited by 42 publications

(53 citation statements)

References 23 publications

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“…Because the closely related brown skua Catharacta antarctica lonnbergi overwinter in the southern ocean (Phillips et al 2007), and hybridize with south polar skua in our study area (Ritz et al 2006), the 2 focal specimens could be hybrids between both skua species. However, a posthoc discriminant analysis including 33 south polar skuas, 16 brown skuas and 9 hybrids (taxa identity was established genetically, Ritz 2009), confirmed a 90% probability for classification as south polar skuas for both individuals.…”

Section: Discussionmentioning

confidence: 98%

South polar skuas from a single breeding population overwinter in different oceans though show similar migration patterns

Kopp¹,

Peter²,

Mustafa³

et al. 2011

Mar. Ecol. Prog. Ser.

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Seabirds in seasonal environments are often long-distance migrants and, for many species and populations, their ranges throughout the non-breeding period are unknown. As conditions during the non-breeding season often affect subsequent performance, the choice of migration strategy can have major implications for timing of breeding and success and, ultimately, population dynamics. We tracked south polar skuas Catharacta maccormicki from a single breeding population at King George Island in the South Shetland Islands (Antarctica). Overall, 27 birds (69%) migrated to the northern Atlantic (3 regions), 10 birds (26%) to the northern Pacific Ocean (2 regions), and 2 birds wintered in the southern hemisphere. Individuals tracked in consecutive non-breeding seasons chose the same ocean for wintering. Despite migrating to different oceans, birds showed a similar figure-ofeight flight pattern and equivalent residency periods in the main wintering areas. In addition, 87% of the migrants used terminal stop-over sites off South America shortly before returning to the breeding site. High diversity of migration patterns may buffer south polar skuas from climate change and other anthropogenic threats.KEY WORDS: Migratory connectivity · Annual cycle · Seabird · Antarctic · Pacific · Trans-equatorial · Geolocator Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 435: [263][264][265][266][267] 2011 & Larsson 1997). However, in the absence of tracking data, there were no studies of the routes or wintering destinations used by specific breeding populations. The purpose of this study was to determine intrapopulation variability in migration patterns of south polar skuas breeding on King George Island, which might theoretically overwinter in either the Pacific or Atlantic oceans. MATERIALS AND METHODSWe equipped 58 adult south polar skuas (27 females, 29 males, 2 unknown sex) with light recording geolocators (British Antarctic Survey, Cambridge) during 3 breeding seasons (2006)(2007)(2008) at King George Island in the Maritime Antarctic (62°12' S, 58°58' W). The geo locators (MK5 and MK9) weighed 9.4 and 8.2 g including the steel ring, respectively, which corresponded to ca. 0.8% of the mean adult body mass. Thirty-nine individuals (18 females, 20 males, 1 unknown sex; all birds were later genetically sexed, Fridolfs son & Ellegren 1999) were recaptured at the same breeding site during consecutive seasons until 2010, resulting in 52 annual tracks. Re-sighting rate did not differ between equipped birds (83%) and breeding birds without a device (78%, logistic regression, Wald = 7.28, p = 0.393). Two positions per day were calculated from light measurements using TransEdit and BirdTracker software (British Antarctic Survey, Cambridge), based on a standard approach (Phillips et al. 2006). Positions that were derived from interrupted light curves around dawn or dusk, that were close to equinoxes, or were obviously erroneous, were excluded, resulting in an average of 331 ± 25 valid...

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Section: Discussionmentioning

confidence: 98%

South polar skuas from a single breeding population overwinter in different oceans though show similar migration patterns

Kopp¹,

Peter²,

Mustafa³

et al. 2011

Mar. Ecol. Prog. Ser.

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“…The largest range overlap with extensive hybridisation is found in the area of the Antarctic Peninsula between South Polar Skua and Brown Skua (Ritz et al, 2006). Up to 12% of breeding pairs in populations within a 500 km wide hybrid zone consist of a South Polar Skua male and a Brown Skua female.…”

Section: Introductionmentioning

confidence: 99%

Phylogeography of the southern skua complex—rapid colonization of the southern hemisphere during a glacial period and reticulate evolution

Ritz

Millar

Miller

et al. 2008

Molecular Phylogenetics and Evolution

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a b s t r a c tWhilst we have now a good understanding how past glaciation influenced species at the northern hemisphere, our knowledge of patterns and modes of speciation is far more limited for the southern hemisphere. We provide mtDNA based data on the phylogeography of a circumpolar distributed southern hemisphere seabird group-the southern skua complex (Catharacta spp.). Diversification of southern skuas dates between 210,000 yBP and 150,000 yBP and coincides with a glacial spanning 230,000-140,000 yBP. Skuas most likely first inhabited the Antarctic continent, in the course of global cooling and increasing glaciation spread to the sub-antarctic islands and Tristan da Cunha and finally colonized Patagonia and the Falkland Islands at the glacial maximum. Despite significant differences between taxa most populations still exchange genes with neighboring populations of other taxa and speciation is incomplete.

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“…In the South Shetland Islands, western Antarctic Peninsula region, the distribution ranges of the closely related south polar skua C. maccormicki and brown skua C. antarctica lonnbergi overlap and they breed sympatrically (reviewed by Ritz et al 2006). Additionally, both species regularly form mixed pairs comprising a south polar skua male and a brown skua female (e.g.…”

Section: Open Pen Access Ccessmentioning

confidence: 99%

Oceanographic and climatic factors differentially affect reproduction performance of Antarctic skuas

Hahn¹,

Reinhardt²,

Ritz³

et al. 2007

Mar. Ecol. Prog. Ser.

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We studied how environmental conditions affect reproduction in sympatric skua species that differ in their reliance on marine resources: the exclusively marine foraging south polar skua Catharacta maccormicki, the terrestrially foraging brown skua C. antarctica lonnbergi and mixed species pairs with an intermediate diet. Egg size, clutch asymmetry and hatching dates varied between species and years without consistent patterns. In the south polar skuas, 12 to 38% of the variation in these parameters was explained by sea surface temperature, sea ice cover and local weather. In mixed species pairs and brown skuas, the influence of environmental factors on variation in clutch asymmetry and hatching date decreased to 10-29%, and no effect on egg size was found. Annual variation in offspring growth performance also differed between species with variable growth in chicks of south polar skuas and mixed species pairs, and almost uniform growth in brown skuas. Additionally, the dependency on oceanographic and climatic factors, especially local wind conditions, decreased from south polar skuas to brown skua chicks. Consistent in all species, offspring were more sensitive to environmental conditions during early stages; during the late chick stage (> 33 d) chick growth was almost independent of environmental conditions. The net breeding success could not be predicted by any environmental factor in any skua species, suggesting it may not be a sensitive indicator of environmental conditions. Hence, the sensitivity of skuas to environmental conditions varied between species, with south polar skuas being more sensitive than brown skuas, and between breeding periods, with the egg parameters being more susceptible to oceanographic conditions. However, during offspring development, local climatic conditions became more important. We conclude that future climate change in the Maritime Antarctic will affect reproduction of skuas more strongly through changes in sea ice cover and sea surface temperature (and the resulting alterations to the marine food web) than through local weather conditions. KEY WORDS: Maritime Antarctic · Sea surface temperature · Sea ice cover · Catharacta spp. · Breeding parameter · Chick growth · Life history 334: 287-297, 2007 spp.) comprise the key resource for almost all higherorder predators in the Antarctic, either representing the main prey for penguins, fishes and whales, or indirectly affecting top predators such as seals and skuas that prey on krill-consuming species. Because the Antarctic food web is comparatively simple (Hempel & Kerry 1990), environmental changes affecting lower food chain levels can also rapidly influence reproduction and population dynamics of top predators (Fraser & Hofmann 2003. Resale or republication not permitted without written consent of the publisher OPEN PEN ACCESS CCESSMar Ecol Prog SerIn studies of polar seabirds, oceanographic factors like sea ice cover and sea surface temperatures have been used as proxies for food accessibility and availability, as the...

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Hybridisation between South polar skua (Catharacta maccormicki) and Brown skua (C. antarctica lonnbergi) in the Antarctic Peninsula region

Cited by 42 publications

References 23 publications

South polar skuas from a single breeding population overwinter in different oceans though show similar migration patterns

South polar skuas from a single breeding population overwinter in different oceans though show similar migration patterns

Phylogeography of the southern skua complex—rapid colonization of the southern hemisphere during a glacial period and reticulate evolution

Oceanographic and climatic factors differentially affect reproduction performance of Antarctic skuas

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