Antarctic Seabirds Research Articles

Nearest neighbors as foraging cues: information transfer in a patchy environment

To assess the importance of both conspecifics and heterospecifics as cues to prey loca- tion, we analyzed patterns of seabird species co-occurrence along shipboard transects conducted near South Georgia (55° S, 35° W) during the austral summer. Using data collected over 9 d and 1500 km ocean, we focused on the behavior of 4 seabird species that are abundant in Antarctic waters: black-browed albatross Thalassarche melanophrys, white-chinned petrel Procellaria aequinoctialis, prion Pachyptila spp., and diving petrel Pelecanoides spp. We identified and recorded the behavior of the nearest neighbors of focal, flying individuals and demonstrated strong intraspecific associa- tions for all 4 species. More conspecific neighbors of prions and diving petrels were also observed fly- ing than expected due to chance. This result suggests that these birds may forage co-operatively with conspecifics. In contrast, more heterospecific neighbors were feeding than expected, and more heterospecific neighbors of white-chinned petrels, prions, and diving petrels were black-browed albatross and groups of penguins and Antarctic fur seals Arctocephalus gazella than expected by chance. We show that associations among foraging birds are not random and are not due to species- specific differences in foraging habitat. We present methods that can be used to measure and com- pare the strength of intra- and interspecific association among predators at sea. Our results suggest that local enhancement is an important component of the foraging strategies of Antarctic seabirds.

BLACK-BROWED ALBATROSSES FORAGING ON ANTARCTIC KRILL: DENSITY-DEPENDENCE THROUGH LOCAL ENHANCEMENT?

Many Antarctic seabirds depend on prey that are patchy, cryptic, ephemeral, and unpredictable in location. These predators typically employ two alternative behavioral strategies for locating resource patches: direct visual or olfactory detection, and indirect detection (local enhancement) by sighting other predators that are already exploiting a patch. We developed a model of direct detection and local enhancement in seabirds that predicts how foraging success varies with behavioral strategy, seabird densities, and prey swarm density and detectability. Application of the model to Black-browed Albatrosses foraging for Antarctic krill near South Georgia suggests that local enhancement is generally a highly effective foraging strategy, and that the fraction of time albatrosses spend in feeding flocks should show strong interactions between prey and conspecific densities. To test these predictions, we analyzed survey data collected near South Georgia in January-March 1986. Our analysis suggests a strong Allee-type density dependence in foraging success that was qualitatively and quantitatively consistent with model predictions. This density dependence suggests a potential for destabilizing patterns of resource utilization and reproductive suc- cess in Black-browed Albatrosses that may have important implications for conservation of albatrosses and other Antarctic species.

Environmental change and Antarctic seabird populations.

Recent changes in Antarctic seabird populations may reflect direct and indirect responses to regional climate change. The best long-term data for high-latitude Antarctic seabirds (Adélie and Emperor penguins and snow petrels) indicate that winter sea-ice has a profound influence. However, some effects are inconsistent between species and areas, some in opposite directions at different stages of breeding and life cycles, and others remain paradoxical. The combination of recent harvest driven changes and those caused by global warming may produce rapid shifts rather than gradual changes.

Trouble in Polar Paradise

G aping ozone holes, collapsing ice sheets, rising temperatures, aboriginal villages swept away: These and other disturbing headlines from the high latitudes show that rapid climate change is under way, and that even the far corners of Earth are not sheltered from its effects. In this special issue, we examine how the polar regions have fared in recent decades and how they may be transformed in a future, warmer world. At the center of global-change research is how the dynamic behavior of the atmosphere and the oceans contributes to the weather patterns that have affected much of the world since the late 20th century. Moritz et al . (p. [1497][1]) discuss how the Arctic climate has changed over the past several decades. By comparing observed Arctic climate variations to modeled patterns, they illustrate how large-scale climate dynamics may have varied in response to human-induced warming. In a News story, Kerr (p. 1490) discusses the implications of an ice-free Northwest Passage in the Arctic Ocean, which many readers may see in their lifetimes. Goldman (p. 1493) describes the hazards of melting permafrost, and Stone (p. [1493][2]) provides a snapshot of an American Association for the Advancement of Science project on pollution and Arctic ecology on Russia's Kola peninsula. One of the greatest concerns related to global warming is how far sea levels will rise if the vast continental ice sheets of Greenland and Antarctica begin to melt. Rignot and Thomas (p. 1502) review what is known about the mass balance of polar ice sheets, based on data collected over the past decade. They show that those ice sheets are much more dynamic than previously thought. In a News story, Kaiser (p. 1494) describes how the Antarctic Peninsula's disintegrating ice shelves may serve as a natural laboratory for studying the melting of mainland ice sheets. Recent changes in Antarctic seabird populations may reflect complex responses, connected with sea ice change, to regional warming. Croxall et al . (p. [1510][3]) explain that more regional environmental data, better ecosystem modeling, and improved knowledge of physical and biological forcing factors are required to understand and predict the responses of seabirds to climate change. The combination of recent harvest-driven changes and those caused by global warming may produce rapid shifts rather than gradual changes. Because of its large surface area, snow is highly reactive. Domine and Shepson (p. 1506) present an overview of how the composition of near-surface air is perturbed by snow and how snowpack chemistry affects snow composition, snowpack interstitial air, and the overlying atmosphere. As a result, the composition of the atmosphere over snowpacks is very different from that predicted by gas-phase chemistry models. Processes taking place in surface snow must be taken into account when ice cores are used to reconstruct past climates. For those interested in knowing more about careers in the frigid high latitudes, a Science 's Next Wave Web feature ([nextwave.sciencemag.org/cgi/content/full/2002/02/26/1][4]) examines how nearly two dozen scientists have made work at the poles a part of their lives. [1]: /lookup/doi/10.1126/science.1076522 [2]: /lookup/doi/10.1126/science.297.5586.1493b [3]: /lookup/doi/10.1126/science.1071987 [4]: http://nextwave.sciencemag.org/cgi/content/full/2002/02/26/1

Feather mercury levels in seabirds at South Georgia: influence of trophic position, sex and age

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 243:261-269 (2002) - doi:10.3354/meps243261 Feather mercury levels in seabirds at South Georgia: influence of trophic position, sex and age Peter H. Becker1,*, Jacob González-Solís2, Brigitte Behrends1, John Croxall3 1Institut für Vogelforschung ŒVogelwarte Helgoland¹, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany 2Departamento Biología Animal (Vertebrats), Universitat de Barcelona, Avenida Diagonal 645, 08028 Barcelona, Spain 3British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, United Kingdom *Email: peter.becker@ifv.terramare.de ABSTRACT: We studied the mercury contamination of 13 species of seabirds breeding on Bird Island, South Georgia, in 1998. Total mercury concentrations in body feather samples of birds caught at their breeding colonies were determined. Among the species, grey-headed albatross (8933 ng g-1) and southern giant petrel (7774 ng g-1) showed the highest, and gentoo penguin (948 ng g-1) the lowest body feather mercury concentrations. Mercury levels were negatively correlated with the proportion of crustaceans (mainly krill) in the species¹ diets, suggesting that the trophic level is the most important factor in explaining the variation of mercury concentrations in Antarctic seabirds. In 4 species studied for age effects among adult birds (grey-headed and black-browed albatross, northern and southern giant petrel), no age-dependent variation in mercury levels was found. Sex differences were also assessed: female gentoo penguins had lower mercury levels than males, which may be related to the elimination of part of the mercury body burden by females into eggs. In contrast, northern giant petrel males had lower levels than females, which may be related to a higher consumption by males of carrion from Antarctic fur seals. In grey-headed albatrosses, mercury levels were 113% higher than in 1989, when this species was investigated at the same site, indicating a possible increase in mercury pollution of the Southern Ocean during the last decade. KEY WORDS: Interspecific variability · Intraspecific variability · Trophic position · Krill diet · Foraging · Temporal trend · Total mercury · Body feathers Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 243. Online publication date: November 13, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.

Long-term population trends in seven Antarctic seabirds at Pointe Géologie (Terre Adélie)

Antarctic seabird populations have been much studied over the last decades as bioindicators of the nature of variability in the Southern Ocean marine ecosystem, and most attention has been focused on the role of food supply and the extent of sea ice. In addition, the rapid spread of tourism and the activities of researchers since the early 1960s have raised questions related to their real and potential impact on bird populations. Our data sets start in 1952 for several species of Antarctic seabirds and this study documents the trends over a 14-year period (1985–1999) in seven species breeding on Pointe Geologie archipelago (Terre Adelie, Antarctica). This is the first study where the direct impact of destruction of breeding sites (for building of an airstrip) is examined and where such long-term populations trends have been assessed in such a number of Antarctic species at one site. Trends from 1985 show that for the whole archipelago and when excluding islands destroyed, Adelie penguins and south polar skuas were the only species to show a significant increase (>3.5% annual change). The others species showed opposite trends, three increasing slightly (southern fulmars +0.4%, cape petrels +2.3%, snow petrels +0.9%) and two decreasing (emperor penguin −0.9%, southern giant petrel −3.9%). Three species particularly affected by the destruction of their breeding habitat (Adelie penguin, cape petrel, snow petrel) showed the capability to restore their populations. The availability of food and nesting sites is discussed in relation to environmental change. Species feeding on krill (Adelie penguins and cape petrels) increased more than other species; however, decrease of ice cover can increase availability of nesting sites. The importance of long-term studies is shown when assessing the role of human activities in Antarctica compared to larger-scale changes.

Associations among Antarctic seabirds in mixed‐species feeding flocks

We studied ten mixed‐species feeding flocks of seabirds and seals off South Georgia (55d̀S, 35d̀W) to assess the factors that influenced the species composition of the flocks. The ten flocks were distributed between two oceanographic regions; four flocks were observed off the northwestern end of South Georgia, and six off the island's southeastern end. The flocks differed dramatically in size and species composition. The northwestern flocks were ten to 20 times larger and contained more seals and penguins. We tested whether these differences were a consequence of location, because the two regions were populated by different assemblages of species, and determined that this was not the case. Differences in flock size and species composition reflected differences in the depth distribution of the birds' and seals' prey. The northwestern flocks were associated with deep swarms of Antarctic krill Euphausia superba with a significant quantity of krill also present at the surface. We also tested for differential flock participation by the species found in the surrounding waters and classified species by their proclivity to participate in the flocks. Our results indicate that Black‐browed Albatross Diomedea melanophris have a strong tendency to join, and diving‐petrels Pelecanoides spp. to avoid, mixed‐species feeding flocks. We postulate that Black‐browed Albatrosses serve as visual cues to the presence of food for one another and for other species, and that diving‐petrels avoid mixed‐species flocks in part because of the risk of predation.

Beak length analysis of the Southern Ocean squid Psychroteuthis glacialis (Cephalopoda: Psychroteuthidae) and its use for size and biomass estimation

A detailed analysis of beak length to body size and mass measurements was carried out for the glacial squid Psychroteuthis glacialis, which is an endemic cephalopod species in the Southern Ocean. Beak lengths (lower rostral length) were measured from 211 specimens which had been sampled in the Atlantic sector of the Southern Ocean. The basic idea was to find some calibration model in order to inter- or extrapolate missing mantle length and/or wet body mass data by means of beak lengths. The relationships between beak length and mantle length/wet body mass bear essential information for future use in biomass estimates in Southern Ocean top predators, since beaks of P. glacialis occur frequently in the stomach contents of Antarctic seabirds, seals and toothed whales. Therefore, lower rostral lengths were plotted against both mantle length and wet body mass to determine the relationship between these variables. The relationships had limited scatter and very high coefficients of determination, showing that lower rostral length is a good predictor of the squid's mantle length and wet mass. A non-linear 3rd order polynomial regression of lower rostral length against mantle length was identified as the best fitted calibration model, explaining 93% (R 2) of the associated variance. The relationship between lower rostral length and wet body mass was empirically well fitted through regressing ln-transformed values of lower rostral length against wet body mass, explaining 95% (R 2) of the associated variance. The present investigation provides measurements for a wide size range of P. glacialis individuals compared to earlier studies, which were limited on very small data sets.

Trophic relationships among Antarctic fulmarine petrels:insights into dietary overlap and chick provisioning strategies inferred from stable-isotope (d15N and d13C) analyses

We used stable-isotope analysis (SIA) to evaluate trophic relationships in an Antarctic seabird community. We determined natural abundances of stable-nitrogen (δ 15 N) and stable-carbon (δ 13 C) isotopes from blood samples (n = 283) from adults and chicks of 4 Antarctic fulmarine petrel species (Fulmarus glacialoides, Thalassoica antarctica, Daption capense and Pagodroma nivea) during 2 consecutive breeding seasons, 1994/1995 and 1995/1996, and from representative prey items. Our objectives were to use the isotope approach to infer trophic status and diet composition within and between species, addressing interspecific and temporal variability within this seabird community, and to investigate potential age-related differences in assumed trophic position within species. Prey δ 13 C values ranged from -26.8‰ in amphipods to -23.9%o in adult Antarctic silverfish. Seabird δ 13 C values ranged from-25.3‰ in Antarctic petrel chicks to -23.8‰ in cape petrel adults. Prey δ 15 N values ranged from 4.0‰ in euphausiids to 10.7 ‰ in adult Antarctic silverfish. Seabird δ 15 N values ranged from 8.4 ‰ in Antarctic petrel adults to 12.0‰ in snow petrel chicks. There was considerable interspecific overlap in assumed trophic positions amongst the 4 petrel species, and we conclude all species consumed fish and krill. Despite this apparent overlap, the range in δ 15 N values for petrels corresponded to the equivalent of 1 full trophic level, and estimated trophic level varied with both species and age. A simple trophic level model, constructed based on the δ 15 N data, predicted trophic levels ranging from 2.3 in krill to 4.7 in snow petrel chicks. Snow petrels and Antarctic fulmars tended to have higher δ 15 N values than Antarctic and cape petrels, suggesting a higher proportion of fish in their diets. Petrel chicks consistently had higher δ 15 N values than adults, which suggests trophic segregation between adults and chicks. We discuss advantages of selectively provisioning chicks with higher trophic level prey. Extensive overlap and a relatively narrow range of δ 15 N values are consistent with a food web comprised of few trophic steps.

Bird orientation at high latitudes: flight routes between Siberia and North America across the Arctic Ocean

Bird migration and orientation at high latitudes are of special interest because of the difficulties associated with different compass systems in polar areas and because of the considerable differences between flight routes conforming to loxodromes (rhumblines) or orthodromes (great circle routes). Regular and widespread east-north-east migration of birds from the northern tundra of Siberia towards North America across the Arctic Ocean (without landmark influences) were recorded by ship-based tracking radar studies in July and August. Field observations indicated that waders, including species such as Phalaropusfulicarius and Calidris melanotos, dominated, but also terns and skuas may have been involved. Analysis of flight directions in relation to the wind showed that these movements are not caused by wind drift. Assuming possible orientation principles based on celestial or geomagnetic cues, different flight trajectories across the Arctic Ocean were calculated: geographical loxodromes, sun compass routes, magnetic loxodromes and magnetoclinic routes. The probabilities of these four alternatives are evaluated on the basis of both the availability of required orientation cues and the predicted flight paths. This evaluation supports orientation along sun compass routes. Because of the longitudinal time displacement sun compass routes show gradually changing compass courses in close agreement with orthodromes. It is suggested that an important migration link between Siberia and North American stopover sites 1000-2500km apart across the Arctic Ocean has evolved based on sun compass orientation along orthodrome-like routes.

Fatty acid composition of the adipose tissue and yolk lipids of a bird with a marine-based diet, the emperor penguin (Aptenodytes forsteri).

The emperor penguin (Aptenodytes forsteri) is an Antarctic seabird feeding mainly on fish and therefore has a high dietary intake of n-3 polyunsaturated fatty acids. The yolk is accumulated in the developing oocyte while the females are fasting, and a large proportion of the fatty acid components of the yolk lipids are derived by mobilization from the female's adipose tissue. The fatty acid composition of the total lipid of the yolk was characterized by high levels of n-3 polyunsaturated fatty acids. However, it differed in several respects from that of the maternal adipose tissue. For example, the proportions of 14:0, 16:1n-7, 20:1n-9, 22:1n-9, 20:5n-3, and 22:6n-3 were significantly greater in adipose tissue than in yolk. Thus adipose tissue lipids contained 7.6+/-0.3% and 8.0+/-0.3% (wt% of total fatty acids; mean +/- SE; n = 5) of 20:5n-3 and 22:6n-3, respectively, whereas the yolk total lipid contained 1.6+/-0.1 and 5.5+/-0.3% of these respective fatty acids. The proportions of 16:0, 18:0, 18:1n-9, 18:2n-6, and 20:4n-6 were significantly lower in the adipose tissue than in the yolk lipids. The proportions of triacylglycerol, phospholipid, free cholesterol, and cholesteryl ester in the yolk lipid were, respectively, 67.0+/-0.2, 25.4+/-0.3, 5.3+/-0.2, and 1.8+/-0.2% (wt% of total yolk lipid). The proportions of 20:4n-6, 20:5n-3, 22:5n-3, and 22:6n-3 were, respectively, 5.7+/-0.3, 2.8+/-0.2, 1.4+/-0.1, and 11.7+/-0.5% in phospholipid and 0.4+/-0.0, 1.2+/-0.1, 0.8+/-0.1 and 3.6+/-0.3% in triacylglycerol. About 95% of the total vitamin E in the yolks was in the form of alpha-tocopherol with gamma-tocopherol forming the remainder. Two species of carotenoids, one identified as lutein, were present.

First census of breeding seabirds between Cap Bienvenue (Terre Adélie) and Moyes Islands (King George V Land), Antarctica: new records for Antarctic seabird populations

Breeding population sizes of penguins, fulmarine etrels and skuas were estimated for the first time on a major part of the Terre Adelie coast and a section of the King George V Land coast during the 1997/1998 austral summer. We counted 106,400 breeding pairs and 12,400 Adelie penguin (Pygoscelis adeliae) chicks by direct counts, and 6960 breeding pairs from aerial photographs. Minimum breeding populations for other species are (direct counts): Antarctic fulmar (Fulmarus glacialoides) 6861 pairs, Antarctic petrel (Thalassoica antarctica) 4574 pairs, cape petrel (Daption capense) 194 pairs, snow petrel (Pagodroma nivea) 767 pairs, south polar skua (Catharacta maccormicki) 129 pairs and subantarctic skua (Catharacta lonnbergi) 1 breeding bird. We discovered 29 new seabird breeding locations in King George V Land, including 6 Antarctic fulmar, 4 Antarctic petrel, 3 cape petrel, 6 snow petrel and 10 south polar skua colonies. The largest colonies found contained up to 4205 breeding pairs of Antarctic fulmars. Population sizes of all species obtained in this study are higher than those found during previous partial surveys. Although these differences are in great part due to differences in survey methods, they also reflect real population changes. Our minimum population sizes obtained for a small portion of the Antarctic coast (<2%) suggest an underestimation of the estimated world breeding populations for several species of Antarctic seabirds.

Olfactory foraging in Antarctic seabirds:a species-specific attraction to krill odors

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 177:235-241 (1999) - doi:10.3354/meps177235 Olfactory foraging in Antarctic seabirds: a species-specific attraction to krill odors Gabrielle Nevitt* Section of Neurobiology, Physiology and Behavior, Division of Biological Sciences, University of California, Davis, California 95616, USA *E-mail: ganevitt @ucdavis.edu ABSTRACT: Antarctic procellariiform seabirds are known for their well-developed sense of smell, yet few behavioral experiments have addressed how these birds use olfactory cues to forage at sea. I describe results from controlled, shipboard experiments performed in Antarctic waters near Elephant Island. Birds were presented with plain or krill-scented (Euphausia superba) vegetable oil slicks, and their behavioral responses were compared. Krill-scented vegetable oil slicks were highly attractive to some but not all procellariiform species foraging in this area (p < 0.001, G-test). Cape petrels Daption capense and southern giant petrels Macronectes giganteus appeared at krill-scented slicks within 1 min, whereas black-browed albatrosses Diomedea melanophris appeared within 3 min. Cape petrels D. capense showed the strongest attraction: these birds were observed as much as 5 times as frequently at krill-scented slicks as compared to unscented control slicks (p < 0.001, G-test), while storm-petrels (Oceanites oceanicus and Fregetta tropica) and Antarctic Fulmars Fulmarus glacialoides responded in equal numbers to krill-scented and unscented slicks. When considered with respect to previously published findings, these results suggest a greater complexity in the significance of odors to the foraging ecology of different tube-nosed species than has commonly been assumed. KEY WORDS: Procellariiform · Olfaction · Antarctica · Petrels · Seabirds · Foraging · Krill Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 177. Publication date: February 11, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

What Causes Body Size Variation in the Snow Petrel Pagodroma nivea?

The Snow Petrel Pagodroma nivea is an Antarctic seabird that shows considerable geographic variation and sexual dimorphism in size, males being on average 10% larger than females. The origin and significance of body size variation in this species remain controversial. Two types P. n. and P. n. minor are said to hybridize at a few localities (Jouventin and Viot 1985). Here, we examine body size variation, mating system, and possible hybridization between the two types of Snow Petrel using 470 individuals from two different breeding sites (Casey and Ad6lieland) where they are suspected to hybridize. We then use measurements of individuals from 12 different populations to test the hypothesis that sexual selection is the factor that has led to sexual dimorphism in that species. At Casey two different populations breed sympatrically, whereas only one population showing great variation in body size was found at Ad6lieland. Mating was assortative by type but hybridization between P. n. and P. n. minor occurred at both sites. Hybridization appears to be more recent at Casey than at Ad6lieland, and results from Casey indicate that hybrids mostly result from pairs consisting of male major and female minor. The considerable body size variation observed at Casey and Ad6lieland probably reflects hybridization of the two types. The amount of sexual dimorphism in size correlates with body size in the 12 Snow Petrel populations studied; sexual dimorphism was greater among populations of the larger type than among populations of the smaller type. These results support the sexual selection hypothesis and suggest that a variety of processes may contribute to the observed patterns of geographic variation in body size in the Snow Petrel. Other hypotheses that seek to explain the evolution of sexual dimorphism are considered and discussed for the Snow Petrel.

Fluctuating concentrations of organochlorine pollutants during a breeding season in two Antarctic seabirds: Adelie penguin and southern fulmar

AbstractDuring the reproductive cycle significant fluctuations of concentrations of organochlorine pollutants were detected in blood and uropygial oil from Adélie penguins (Pygoscelis adeliae) and southern fulmars (Fulmarus glacialoides) from Hop Island, Antarctica. In the Adélie penguin, concentrations of polychlorinated biphenyls (PCBs) and dieldrin were significantly higher at the moment of egg laying, while hexachlorobenzene (HCB) and 2,2‐bis(p‐chlorophenyl)‐1,1‐dichloroethylene (p,p′‐DDE) concentrations peaked at the creche stage. Subcutaneous fat is the main pool for HCB and p,p′‐DDE, while PCBs and dieldrin are also stored in the pectoral muscle. It is hypothesized that the observed differences in seasonal fluctuations in organochlorine levels are related to utilization of different storage pools by the Adélie penguins at different moments in the breeding season. In the southern fulmar the fluctuations in concentrations of HCB and p,p′‐DDE can be related to changes in body mass. However, concentrations of PCBs and dieldrin did not vary significantly during the season. It seems that the two groups of compounds are governed more or less independently in the southern fulmar as well. Age‐dependent accumulation of most organochlorines studied reached a steady state before the age at which both species start to breed. This allows monitoring of individual birds to analyze changes in concentrations of organochlorine pollutants in the ecosystem, without having to correct for age differences. Differences in levels of organochlorine pollutants between the Adélie penguin and southern fulmar were probably the result of differences in feeding ecology.

Trans-nonachlor, octachlorostyrene, mirex and photomirex in Antarctic seabirds

Octachlorostyrene (OCS) and trans-nonachlor (TNC) were detected in cape petrels (Daption capense) of King George Island, which tallies with their presence in samples of gentoo penguins (Pygoscelis papua) of the Falkland Islands. The detection of TNC in a sample of the Antarctic southern fulmar (Fulmarus glacialoides) implies that the Antarctic region has been contaminated by this compound. Mirex and photomirex were also detected in samples of the cape petrels and southern fulmar, as well as in Adélie penguins (Pygoscelis adeliae) from Hop Island. The ratios of the mirex and photomirex concentrations in the truly Antarctic species from different locations are similar, which suggests that these compounds are diffusely distributed over the continent. The detection of organochlorine pollutants in Antarctic seabirds is an indication that these compounds have a global distribution. Screening of subcutaneous fat of Antarctic seabirds for organochlorines provides an excellent indication of the occurrence of organochlorine pollutants in Antarctica, and as such an ‘early warning’ for the global dispersion of these compounds.

Directed transport of volatile organochlorine pollutants to polar regions: the effect on the contamination pattern of Antarctic seabirds

Polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) were analyzed in preen oil from birds from Antarctica, Sub-Antarctica and Europe. Antarctic and Sub-Antarctic birds contained unexpected high levels of volatile PCB-congeners and HCB compared to birds from temperate areas. This shows that the so-called cold-condenser effect causes concentrations of volatile organochlorine pollutants in Antarctic top-predators that are higher than in animals in more moderate climates close to the source of these pollutants. Antarctic top predators can be regarded as an utmost sink for volatile persistent pollutants. The levels of HCB indicate that seabirds from Sub-Antarctic regions are at risk to effects of organochlorine pollutants. Also Antarctic birds are potentially at risk, because of the high levels of HCB in combination with their extreme variability in physiological condition throughout the breeding season. When assessing the environmental impact of a contaminant this global effect should be of concern.

Species-Habitat Relationships among Antarctic Seabirds: A Function of Physical or Biological Factors?

Species-Habitat Relationships among Antarctic Seabirds: A Function of Physical or Biological Factors?

High annual variability in reproductive success and survival of an Antarctic seabird, the snow petrel Pagodroma nivea : A 27-year study.

Demographic parameters were estimated for snow petrels Pagodroma nivea nesting at Pointe Géologie Archipelago, Adélie Land, Antarctica between 1963 and 1990; 21 years of data on adult survival and 27 years of data on breeding success are available. The average age of first return and first breeding were 8.1 and 9.9 years respectively and there was no signifcant difference between the sexes. The overall breeding success averaged 51.3% and was very variable between years (21-80%). Breeding failure was mostly due to incubation failure and annual breeding success was negatively correlated with average snow falls in October-November and October-March. Breeding frequency was very low, averaging 52% of seasons during a reproductive lifetime. Good quality sites, with high occupancy rate and high breeding success were few in the study plots. Poor years in 1966-1967, 1976-1977 and 1983-1984, with low breeding success, very low proportions of nets with breeding attempts and high numbers of non-breeders, occurred 1 year after large-scale El Niño Southern Oscillation (ENSO) events. Snow petrels exhibited very low philopatry. Only 45 birds have been recovered in the study plots from a total of 1115 banded fledglings giving an estimated rate of return of 12.9% between fledging and 3 years old. Annual survival between 3 and 10 years was 91.4%. Annual adult survival (93.4%), though variable, was low during poor years of 1977-1978 and 1983-1984. Adult survival of males (94.7%) was not significantly different from that of females (93.9%). Over the study period, the population of Pointe Géologie was stable. Using the estimated parameters, a Leslie model gave a growth rate of 0.948%, which was probably compensated by immigration (5.7% per year). Restricted numbers of good-quality sites at the place of birth could have led young birds to prospect other colonies and could have selected low philopatry. High adult survival, strong site tenacity and capacity to spread breeding over a long lifetime are probably part of the adaptive strategy of this small fulmarine petrel facing highly variable environmental conditions.

Ventilatory Oxygen Extraction in Relation to Ambient Temperature in Four Antarctic Seabirds

We tested the hypothesis that at low ambient temperatures (Ta) birds reduce ventilatory heat loss by increasing ventilatory oxygen extraction (Eo2). We examined relationships between Ta, body temperature, oxygen consumption (V̇o2), carbon dioxide production (V̇co2), evaporative water loss (ṁH2O), respiratory frequency, tidal volume (VT), minute volume, and Eo2, in four species of Antarctic marine birds ranging in body mass from 33-4,915 g The factorial increases in V̇o2 ranged from 1.8 to 5.2 between the lower critical temperature (Tlc; 10° -30° C, depending on species) and a Ta of -23°C. The respiratory exchange ratio (V̇co2/V̇o2) did not change with Ta. The ṁH2O was independent of Ta between 10° and 30° C in kelp gulls and giant petrels but was positively correlated with Ta between 10° and 35° C in Wilson's storm-petrels and between 10° and 30° C in South Polar skuas. Thermal conductance (C) was minimal at Ta's of 10° or 20° C depending on the species and was constant and low at Ta's below this minimum. In all four species C increased significantly at high Ta's. In storm-petrels, gulls, and skuas, the increase in V̇o2, resulting from a change in Ta from Tlc down to -23°C was accommodated mainly by increasing VT. In contrast, in giant petrels the increase in V̇o2 resulting from a change in Ta from Tlc down to -23°C was accommodated mainly by increasing Eo2, and the increase in VT was of secondary importance. Our data suggest that increasing Eo2, as a means of reducing ventilatory heat loss is not a general phenomenon in cold-adapted birds.