Publications

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evidence of ortho- and paramyxoviruses in fauna from antarctica.serum antibodies to influenza a viruses and paramyxoviruses were detected in adelie penguin (pysoscelis adeliae) and antarctic skua (stercorarius skua maccormicki) sera in the ross sea dependency. an avian paramyxovirus was isolated from a penguin cloacal swab.19938258855
organochlorine compounds and their metabolites in seven icelandic seabird species - a comparative study.the present study is designed to assess the occurrence of a few organochlorine contaminants and their metabolites in eggs of different marine bird species in iceland, a country located in the sub-arctic of the north-western atlantic. previous investigations from e.g. sweden and the netherlands have shown some obvious differences in contaminant concentrations, including e.g. hydroxylated polychlorinated biphenyl metabolites (oh-pcbs) in guillemot (uria aalge) and other bird species. eggs from sev ...201020356092
decline in an atlantic puffin population: evaluation of magnitude and mechanisms.determining which demographic and ecological parameters contribute to variation in population growth rate is crucial to understanding the dynamics of declining populations. this study aimed to evaluate the magnitude and mechanisms of an apparent major decline in an atlantic puffin fratercula arctica population. this was achieved using a 27-year dataset to estimate changes in population size and in two key demographic rates: adult survival and breeding success. estimated demographic variation was ...201526177461
plastic debris in great skua (stercorarius skua) pellets corresponds to seabird prey species.plastic is a common item in marine environments. studies assessing seabird ingestion of plastics have focused on species that ingest plastics mistaken for prey items. few studies have examined a scavenger and predatory species that are likely to ingest plastics indirectly through their prey items, such as the great skua (stercorarius skua). we examined 1034 regurgitated pellets from a great skua colony in the faroe islands for plastics and found approximately 6% contained plastics. pellets conta ...201626763326
polybrominated diphenyl ethers (pbdes) and hexabromocyclododecane (hbcd) in seven different marine bird species from iceland.data on distribution, concentration and trends of polybrominated diphenyl ethers (pbdes) and hexabromocyclododecanes (hbcds) is scarce in biota from the sub-arctic region of the atlantic. the present study is an investigation on pbde and hbcd concentrations in eggs from seven marine bird species from iceland, i.e. common eider (somateria mollissima), arctic tern (sterna paradisaea), guillemot (uria aalge), fulmar (fulmarus glacialis), lesser black-backed gull (larus fuscus), great black-backed g ...201323987577
feathers as a means of monitoring mercury in seabirds: insights from stable isotope analysis.mercury concentrations, together with nitrogen and carbon stable isotope signatures, were determined in body feather samples from northern fulmars fulmarus glacialis and great skuas catharacta skua, and in different flight feathers from great skuas. there were no significant relationships between trophic status, as defined using isotope analysis, and mercury concentration in the same feather type, in either species. mercury concentrations in body feather samples were markedly different between f ...199815093080
changes in fisheries discard rates and seabird communities.it is clear that discards from commercial fisheries are a key food resource for many seabird species around the world. but predicting the response of seabird communities to changes in discard rates is problematic and requires historical data to elucidate the confounding effects of other, more 'natural' ecological processes. in the north sea, declining stocks, changes in technical measures, changes in population structure and the establishment of a recovery programme for cod (gadus morhua) will a ...200414973483
multiple stressors in a top predator seabird: potential ecological consequences of environmental contaminants, population health and breeding conditions.environmental contaminants may have impacts on reproduction and survival in wildlife populations suffering from multiple stressors. this study examined whether adverse effects of persistent organic pollutants (pops) increased with poor population health and breeding conditions in three colonies (60-74°n) of great skua (stercorarius skua) in the north-eastern atlantic (shetland, iceland and bjørnøya [bear island]). pops (organochlorines [ocs] and polybrominated diphenyl ethers [bdes]) were measur ...201526172383
great skua (stercorarius skua) movements at sea in relation to marine renewable energy developments.marine renewable energy developments (mreds) are an increasing feature of the marine environment. owing to the relatively small number of existing developments and the early stage of their associated environmental monitoring programmes, the effects of mreds on seabirds are not fully known. our ability to fully predict potential effects is limited by a lack of knowledge regarding movements of seabirds at sea. we used gps tracking to improve our understanding of the movements at sea of a protected ...201425262489
feather corticosterone levels on wintering grounds have no carry-over effects on breeding among three populations of great skuas (stercorarius skua).environmental conditions encountered by migratory seabirds in their wintering areas can shape their fitness. however, the underlying physiological mechanisms remain largely unknown as birds are relatively inaccessible during winter. to assess physiological condition during this period, we measured corticosterone concentrations in winter-grown primary feathers of female great skuas (stercorarius skua) from three breeding colonies (bjørnøya, iceland, shetland) with wintering areas identified from ...201424964085
dietary versus maternal sources of organochlorines in top predator seabird chicks: an experimental approach.we examined the relative importance of dietary sources and maternal transfer on organochlorine concentrations (∑ocs) in great skua chicks (stercorarius skua) in shetland by food supplementing parents with known wintering area. we predicted that experimental chicks (whose parents were supplemented) should have (i) higher growth rates and, (ii) lower ∑ocs due to growth dilution effect and/or due to being fed with less contaminated food compared to control chicks. we also predicted a significant in ...201323672486
organohalogen contaminants and blood plasma clinical-chemical parameters in three colonies of north atlantic great skua (stercorarius skua).the present study compares blood plasma clinical-chemical parameters (bccps) in birds from three geographically distinct north atlantic great skua (stercorarius skua) colonies. birds from these sites bioaccumulate different pop (persistent organic pollutant) concentrations and that enabled us to compare great skua bccps in different exposure scenarios. persistent organic pollutants (organochlorines: pcb, ddt, chlordanes, hcb, hch, mirex and brominated flame retardants: pbdes) and nineteen bccps ...201323537726
perfluoroalkyl substances in eggs and plasma of an avian top predator, great skua (stercorarius skua), in the north atlantic.temporal, biological, and environmental factors affecting accumulation of perfluoroalkyl substances (pfass) are poorly understood in comparison with legacy lipid-soluble persistent organic pollutants. temporal and biological comparisons of pfas concentrations were made in great skuas (stercorarius skua), a marine apex predator. concentrations of 16 pfass were quantified, including c4-c10 perfluorosulfonates (pfsas), perfluorooctanesulfonamide (pfosa), and c5-c14 perfluorocarboxylates (pfcas). co ...201323258709
individual variation in biomarkers of health: influence of persistent organic pollutants in great skuas (stercorarius skua) breeding at different geographical locations.persistent organic pollutants (pops) have been shown to cause adverse effects on a number of biomarkers of health in birds. pops may impair immune function and alter the stress response, defined as a suite of behavioral and physiological responses to environmental perturbations. recent studies have also proposed that pops can induce oxidative stress. nevertheless, there is a lack of studies simultaneously assessing the potential damaging effects of pops on the latter biomarkers. in this study, w ...201222921737
effects of environmental exposure and diet on levels of persistent organic pollutants (pops) in eggs of a top predator in the north atlantic in 1980 and 2008.concentrations of pops in great skua eggs from shetland are among the highest in north atlantic seabirds, with up to 11,600 μg/kg (ww) dde and up to 17,900 μg/kg ww ∑pcb. concentrations of legacy pops were significantly lower in 2008 than 1980. decreases were greatest for least persistent compounds. median ∑pbdes increased from 99 μg/kg ww in 1980 to 173 μg/kg ww in 2008. there were changes in great skua breeding season diet, with more adult herring and mackerel and less sandeel. these changes i ...201121342740
ossification sequence of the common tern (sterna hirundo) and its implications for the interrelationships of the lari (aves, charadriiformes).the hypotheses of relationships within lari (gulls) are highly unstable, and depend on whether morphological or molecular data are examined. developmental sequence data are thought to contain phylogenetic information, but have never been applied to the problem of avian systematics. in this article, we describe the ossification sequence of the common tern (sterna hirundo), and compare the pattern observed to published descriptions of other charadriiformes, specifically the great skua (stercorarii ...200818570230
factors that influence assimilation rates and fractionation of nitrogen and carbon stable isotopes in avian blood and feathers.by switching great skuas catharacta skua from one isotopically distinct diet to another, we measured diet-tissue discrimination factors and tested the assumption that dietary nitrogen and carbon isotope signatures are incorporated into blood and feathers at similar rates. we also examined the effects of metabolic rate and looked for evidence of isotopic routing. we found that blood delta(15)n and delta(13)c signatures altered after the diet switch at similar rates (14.4 d and 15.7 d, respectivel ...200612529846
increased reproductive effort results in male-biased offspring sex ratio: an experimental study in a species with reversed sexual size dimorphism.adaptive sex-ratio theory predicts that parents should overproduce the more beneficial offspring sex. based on a recent experimental study of lesser black-backed gulls, we tested this hypothesis with the great skua, catharacta skua, a bird species closely related to gulls but where females are the larger sex. when in poor body condition, the gulls overproduced daughters, the smaller and more viable sex under those circumstances. to discriminate between a mandatory physiological overproduction of ...200111600083
partnerships and mechanisms of divorce in the great skua.there are two main theories attempting to explain divorce in birds as an adaptive decision for at least one of the members of the pair. the 'incompatibility hypothesis' states that birds separate because they are unsuccessful breeders as a pair, although their individual characteristics are not negative per se. divorce comes about as an initiative of both individuals to search for a more compatible mate. the 'better option hypothesis' suggests that divorce is usually initiated by one of the bird ...19979794773
the interactive effects of age and food supply on the breeding ecology of great skuas.age-specific variation in the reproductive performance of great skuas in shetland, u.k., was investigated during a period of fluctuating sandeel availability between 1988 and 1993. increased sandeel abundance was associated with earlier laying dates, increased clutch volumes and improved fledging success. sandeel abundance had no effects on clutch size and hatching success. parental age improved haying date and clutch size in a nonlinear manner. laying date became earlier in the youngest age cla ...199826412366
territorial intrusions and copulation behaviour in the great skua, catharacta skuabirds of many species intrude on to territories in order to obtain extra-pair copulations, and frequent within-pair copulations are thought to be a response to cuckoldry where mate guarding is not possible. great skuas are colonial birds in which females are left alone in the breeding territory while males forage for the pair. opportunities for cuckoldry are therefore numerous, and it could be predicted that sperm competition should be intense in this species. we tested several hypotheses that a ...19979398379
legacy pollutants are declining in great skuas (stercorarius skua) but remain higher in faroe islands than in scotland.to monitor environmental pollutants in faroese biota, samples from a top predator were analysed and put into a spatial and temporal context. analysis of 20 great skua eggs sampled in 2012 from the faroe islands showed >70 % lower concentrations of legacy persistent organic pollutants (pops) than in samples analysed in 1977. the 2012 faroese eggs showed higher concentrations than for eggs in shetland from about the same period (2008). eggshells were analysed for sub-lethal effects but there were ...201627329112
enigmatic phylogeny of skuas (aves:stercorariidae)multiple sources of evidence show that the skuas (aves:stercorariidae) are a monophyletic group, closely related to gulls (laridae. on morphological and behavioural evidence the stercorariidae are divided into two widely divergent genera, catharacta and stercorarius, consistent with observed levels of nuclear and mitochondrial gene divergence. catharacta skuas are large-bodied and with one exception breed in the southern hemisphere. stercorarius skuas otherwise known as jaegers) are smaller bodi ...19979061968
chlorinated hydrocarbons in the tissues of south polar skuas (catharacta maccormicki) and adélie penguins (pygoscelis adeliea) from ross sea, antarctica.high rates of egg infertility and embryo death in a colony of south polar skuas breeding in the antarctic were similar to those in polluted north atlantic populations of the great skua. such loss could not be linked to factors such as organochlorine pollutants, as levels of dde and pcbs in the contents of skua eggs from the population were only a small fraction of those in polluted skua populations from the northern hemisphere. average eggshell thickness for skuas nesting on ross island has show ...199715093368
dna damage in arctic seabirds: baseline, sensitivity to a genotoxic stressor, and association with organohalogen contaminants.environmental contaminants are found throughout arctic marine ecosystems, and their presence in seabirds has been associated with toxicological responses. however, there are few studies of genotoxicity in arctic avian wildlife. the purpose of the present study was to quantify deoxyribonucleic acid (dna) damage in lymphocytes of selected seabird species and to examine whether accumulation of organohalogen contaminants (σohcs) affects dna damage. blood was sampled from common eider (somateria moll ...201729120089
flexibility of foraging strategies of the great skua stercorarius skua breeding in the largest colony in the barents sea region.foraging strategies of seabird species often vary considerably between and within individuals. this variability is influenced by a multitude of factors including age, sex, stage of annual life cycle, reproductive status, individual specialization and environmental conditions.201829588648
the genetic basis and enigmatic origin of melanic polymorphism in pomarine skuas (stercorarius pomarinus).a key outstanding issue in adaptive evolution is the relationship between the genetics of intraspecific polymorphism and interspecific evolution. here, we show that the pale/dark ventral plumage polymorphism that occurs in both the pomarine skua (stercorarius pomarinus) and arctic skua (s. parasiticus) is the result of convergent evolution at the same locus (mc1r), involving some of the same amino acid sites. the dark melanic mc1r allele in the pomarine skua is strongly divergent from the pale m ...201729187628
stable isotopes reveal the importance of seabirds and marine foods in the diet of st kilda field mice.introduced mammals have devastated island nesting seabird populations worldwide. declines in breeding seabirds on st kilda, uk, have been linked to climate change and predation from great skuas stercorarius skuas, but the introduced st kilda field mouse apodemus sylvaticus hirtensis may also play a role by feeding on adults, chicks or eggs. here, we use stable isotopes in st kilda mouse blood and potential dietary items to investigate their foraging ecology, specifically focussing on the importa ...202032269251
the effect of long-range transport, trophic position and diet specialization on legacy contaminant occurrence in great skuas, stercorarius skua, breeding across the northeast atlantic.high levels of halogenated organic contaminants (hocs) have been found in the marine predatory seabird great skua (stercorarius skua) from breeding colonies in the northeastern atlantic, with large unexplained inter-colony variation. the present study aimed at analyzing if the hocs occurrence in breeding great skuas in remote colonies was explained by local baseline food web exposure determined by long-range transport, or by ecological factors such as diet specialization and relative trophic pos ...201930321712
combined bottom-up and top-down pressures drive catastrophic population declines of arctic skuas in scotland.understanding drivers of population change is critical for effective species conservation. in the northeast atlantic ocean, recent changes amongst seabird communities are linked to human and climate change impacts on food webs. many species have declined severely, with food shortages, and increased predation reducing productivity. arctic skua stercorarius parasiticus, a kleptoparasite of other seabirds, is one such species. the aim of the study was to determine relative effects of bottom-up and ...201830155905
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