Macronectes Research Articles

Breeding sites and population of seabirds on Admiralty Bay, King George Island, Antarctica

The monitoring of the status and distribution of seabird populations is necessary to understand their spatial and temporal responses to rapid climate changes occurring in the Western Antarctic Peninsula area. We surveyed and mapped Admiralty Bay bird communities and related them to climate variables—temperature, temperature anomaly, Antarctic Oscillation Index and El-Nino Southern Oscillation Index. We recorded 13 breeding seabird species over three seasons (2009/2010, 2010/2011 and 2011/2012) and mapped 10 of them over an area of 149.5 ha. The ice-free areas with the greatest number of species were Point Thomas, Keller Peninsula and Hennequin Point. The most abundant species was the Adelie Penguin (Pygoscelis adeliae) followed by the Chinstrap Penguin (P. antarcticus). We observed that the number of breeding pairs of Gentoo Penguins (P. papua), Chinstrap Penguins and skuas (Catharacta maccormicki and C. antarctica) are related to temperature, temperature anomaly and El-Nino Southern Oscillation Index. The size of breeding populations and their distributions have been fluctuating over the last 30 years in ice-free areas of Admiralty Bay. Most species showed a decreasing trend from 1978 to 2012, with the exception of Chinstrap Penguins, Southern Giant Petrels (Macronectes giganteus) and skuas, which seem to be stable in numbers in the last two decades. Decreases in seabird populations from the Antarctic Peninsula are widely recognized as a response to environmental change and anthropogenic influences such as tourism and building activities, thus highlighting the importance of monitoring to support mitigation measures.

Assessing the structure and temporal dynamics of seabird communities: the challenge of capturing marine ecosystem complexity.

Summary Understanding interspecific interactions, and the influences of anthropogenic disturbance and environmental change on communities, are key challenges in ecology. Despite the pressing need to understand these fundamental drivers of community structure and dynamics, only 17% of ecological studies conducted over the past three decades have been at the community level.Here, we assess the trophic structure of the procellariiform community breeding at South Georgia, to identify the factors that determine foraging niches and possible temporal changes. We collected conventional diet data from 13 sympatric species between 1974 and 2002, and quantified intra‐ and inter‐guild, and annual variation in diet between and within foraging habits. In addition, we tested the reliability of stable isotope analysis (SIA) of seabird feathers collected over a 13‐year period, in relation to those of their potential prey, as a tool to assess community structure when diets are diverse and there is high spatial heterogeneity in environmental baselines.Our results using conventional diet data identified a four‐guild community structure, distinguishing species that mainly feed on crustaceans; large fish and squid; a mixture of crustaceans, small fish and squid; or carrion. In total, Antarctic krill Euphausia superba represented 32%, and 14 other species a further 46% of the combined diet of all 13 predators, underlining the reliance of this community on relatively few types of prey. Annual variation in trophic segregation depended on relative prey availability; however, our data did not provide evidence of changes in guild structure associated with a suggested decline in Antarctic krill abundance over the past 40 years.Reflecting the differences in δ15 N of potential prey (crustaceans vs. squid vs. fish and carrion), analysis of δ15 N in chick feathers identified a three‐guild community structure that was constant over a 13‐year period, but lacked the trophic cluster representing giant petrels which was identified using conventional diet data.Our study is the first in recent decades to examine dietary changes in seabird communities over time. Conventional dietary analysis provided better resolution of community structure than SIA. However, δ15 N in chick feathers, which reflected trophic (level) specialization, was nevertheless an effective and less time‐consuming means of monitoring temporal changes.

Seabird colony effects on soil properties and vegetation zonation patterns on King George Island, Maritime Antarctic

Seabirds are among the most important vectors transferring biogenic compounds from the sea onto land in the polar regions and, consequently, influencing the properties of soil and vegetation. We studied the influence of bird colonies (Adelie penguin Pygoscelis adeliae, gentoo penguin P. papua and giant petrels Macronectes giganteus) on soil properties and plant communities on King George Island, Maritime Antarctic. We designated seven transects, each starting from the colony edge and running to a natural boundary feature, which were divided into contiguous sample plots where we identified specific plant taxa (Prasiola crispa, Deschampsia antarctica, Colobanthus quitensis, Usnea sp.), as well as hydrophilous and xerophilous ecological groups of mosses. Based on percentage contributions of each of these taxa, we distinguished six distinct vegetation zones along the transects, in which we measured physical (moisture, conductivity and pH) and chemical (NO3 −, NO2 −, NH4 +, K+ and PO4 3− content) soil parameters. Our study confirmed that, with increasing distance from bird colonies, the concentration of nutrients and soil conductivity decreased, while pH increased. The vegetation zones were clearly related to this gradient of seabird colony influence and occurred in the same sequence for all three bird species examined, although the largest colony of Adelie penguins had the strongest effect on vegetation. Similarly, the physical and chemical soil properties did not differ significantly between the colonies.

Hybridization and back-crossing in giant petrels (Macronectes giganteus and M. halli) at Bird Island, South Georgia, and a summary of hybridization in seabirds.

Hybridization in natural populations provides an opportunity to study the evolutionary processes that shape divergence and genetic isolation of species. The emergence of pre-mating barriers is often the precursor to complete reproductive isolation. However, in recently diverged species, pre-mating barriers may be incomplete, leading to hybridization between seemingly distinct taxa. Here we report results of a long-term study at Bird Island, South Georgia, of the extent of hybridization, mate fidelity, timing of breeding and breeding success in mixed and conspecific pairs of the sibling species, Macronectes halli (northern giant petrel) and M. giganteus (southern giant petrel). The proportion of mixed-species pairs varied annually from 0.4–2.4% (mean of 1.5%), and showed no linear trend with time. Mean laying date in mixed-species pairs tended to be later than in northern giant petrel, and always earlier than in southern giant petrel pairs, and their breeding success (15.6%) was lower than that of conspecific pairs. By comparison, mixed-species pairs at both Marion and Macquarie islands always failed before hatching. Histories of birds in mixed-species pairs at Bird Island were variable; some bred previously or subsequently with a conspecific partner, others subsequently with a different allospecific partner, and some mixed-species pairs remained together for multiple seasons. We also report the first verified back-crossing of a hybrid giant petrel with a female northern giant petrel. We discuss the potential causes and evolutionary consequences of hybridization and back-crossing in giant petrels and summarize the incidence of back-crossing in other seabird species.

Конкурентні взаємини птахiв Антарктики в локальному осередку людської дiяльностi (на прикладі УАС «Академiк Вернадський»)

The example of interspecies relationship birds-euryphages Aпtarctic species displayed competition in artificial trophic localities - in the hearth of recycling kitchen waste. ln particular, Kelp Gull (Larus dominicanus), South Polar Skua (Catharacta maccormicki), Pale-faced Sheathbill (Chionis alba) and Southern Giant Petrel (Macronectes giganteus) form а commensal relationship with the employees of the station (useful for birds and indifferent for men). At the same time, between themselves they show the hard rivalry of the trophic resources. Seagulls are the main species of avifauna, which for the year is changing its competitors. From November to April skuas are competitors for the gulls. They have а superiority in the number for February and March. Since the second half of April gulls compete with sheathbills. The gradual disappearance of sheathbills observed in winter - as а consequence of the appearance and aggression of skuas. ln summer, near the station occasionally observed petrels, which in spite of а small synanthropes, monopolize feed.

INFLUENZA DETECTED IN Macronectes giganteus IN TWO ISLANDS OF SOUTH SHETLANDS, ANTARCTICA

Influenza A virus was detected in different species of birds and migratory aquatic birds. They are the main reservoir of the virus. In this research we detected the first Influenza A virus in Southern Giant Petrel in an Antarctic region. The results represent 0.33% of the samples collected in two breeding areas of the species. Some factors can explain the introduction of these pathogens and diseases in Antarctica, such as bird's migratory behavior and the remains of the virus in cold waters.

DIET OF SOUTHERN GIANT PETREL CHICKS IN ANTARCTICA: A DESCRIPTION OF NATURAL PREYS

This study aims to describe the food resource of Southern Giant Petrel during the chick-rearing period in Antarctica. The study was conducted in Stinker Point, Elephant Island in the Austral Summer of 2012/2013. Samples were collected randomly from chicks by flushing methods. In the laboratory all the items were identified and the frequency of occurrence was calculated. We identified twelve different items in the diet of SGP chicks. The most frequent item was the remains of seabird species, followed by crustaceous and cephalopods. This study presents new ecological data on the species, since studies on Antarctic populations are scarce.

Characterization of the seascape used by juvenile and wintering adult Southern Giant Petrels from Patagonia Argentina

The characterization of the seascape used by marine top predators provides a wide perspective of pelagic habitat use and it is necessary to understand the functioning of marine systems. The goal of this study was to characterize the oceanographic and biological features of marine areas used by adult and first year juvenile southern giant petrels (SGP, Macronectes giganteus) from northern Patagonian colonies (Isla Arce and Gran Robredo) during the austral fall and winter (2005, 2006, 2007, and 2008). The marine environment exploited by the SGP was characterized using sea surface temperature (SST), SST gradients, chlorophyll-a concentration, water depth, oceanographic regimes, and ocean surface winds. In addition, the biological seascape was defined by considering the distribution of squid during the months of study. Juveniles SGP exploited a wide range of environments focusing mainly on productive neritic waters using a variety of oceanographic regimes. Juveniles were exposed to eutrophic and enriched waters, probably because of the frequent presence of thermal fronts in their utilization areas. Adults' environments lacked of thermal fronts remaining the majority of their time within the oceanographic regime “Continental Shelf”, in water depths of 100–200 m, exploiting mesotrophic and eutrophic environments, and remaining in areas of known food resources related to the presence of squid. For the most part, juveniles were exposed to westerly winds, which may have helped them in their initial flight to the shelf break, east of the colony. Wintering adults SGP also explored areas characterized by westerly winds but this did not play a primary role in the selection of their residence areas. Juveniles during their first year at sea have to search for food exploring a variety of unknown environments. During their search, they remained in productive environments associated to fronts and probably also associated to fisheries operating in their foraging areas. The understanding of pelagic birds' habitat selection and preferences through the year is crucial for the monitoring of anthropogenic impacts over these species. Further studies should focus on the prediction of variables that determine the distribution of these species though the year and during different life stages.

Southern giant Petrel Macronectes giganteus nest attendance patterns under extreme weather conditions.

Differences in nest attendance between genders in seabirds may be related to morphological differences. Southern giant petrel is a dimorphic species with gender-specific foraging behavior. The objective of this study was to investigate sex-related differences in nest attendance during the breeding period of southern giant petrels by presence/absence patterns of both sexes during incubation and compare use of the colony after nest failure. Fourteen birds were tagged with digitally coded radio-transmitters in a colony at Elephant Island, Antarctica, in the beginning of 2009/2010 breeding season. Females were present during 18 periods (min. 3 days, max. 9 days) and males only in five periods (min. 2 days, max. 13 days). The difference in mean number of radio signals per day between females (4330; s.e. 313.5) and males (2691; s.e. 248.6) was highly significant (t = 4.3; d.f. = 199; P < 0.001; Fig. 4 ). As consequence of the severe weather conditions that year, all tagged birds failed to reproduce. After abandonment of the nests, the presence of both genders decreased drastically, although the tagged individuals stayed in the area. Under severe weather conditions female Southern Giant Petrels continue breeding while males abandon the nest earlier.

Differential use of the Argentine shelf by wintering adults and juveniles southern giant petrels, Macronectes giganteus, from Patagonia

To study habitat use and at-sea movements of southern giant petrels (SGP) during non-breeding period, we deployed 15 satellite transmitters (six adults, nine juveniles) at Isla Arce and Isla Gran Robredo colonies in Patagonia, Argentina. Birds were instrumented during 81.4 ± 37 days. Adult birds used 74% of the Argentine shelf concentrating mainly at the shelf break, middle shelf waters, and the surroundings of the colony. After fledging, juveniles spread to the Argentine, Uruguayan and Brazilian shelves within the South Atlantic. Adults alternated at-sea excursions (12 ± 5 days) with periods at the colony of 3 ± 0.3 days. Contrarily, juveniles moved first to the shelf break and then traveled northwards reaching the south of Brazil. There was some spatial overlap between age classes, but only during the first 30 days after juveniles had fledged; thereafter there was not overlap between the areas used by both age classes. The Argentine shelf is widely used by different species offering a suitable environment for foraging; this may be why adults SGP from Patagonian colonies spend all year-round within the Argentine shelf. The identification of used areas of non-breeding SGP fills a gap in the species knowledge contributing not only to the preservation the species, but also to the management of marine areas globally recognized as important for many other Procellariiformes.

Depredación del lobo marino común Otaria flavescens sobre el pingüino de penacho amarillo Eudyptes c. chrysocome en isla Gonzalo, Diego Ramírez, sur de Chile

During the summer season 2010-2011 was studied the predation of Otaria flavescens on Eudyptes chrysocome chrysocome in Gonzalo Island (56°31'S; 68°42'W), Diego Ramirez archipelago, southern Chile. In total, 75 attacks of sea lion on penguins were recorded, from which 34 (45.3%) corresponded to successful attacks and kill of penguins. Among recorded behaviors during attacks, we highlight: i) persecutions during penguin's swimming, ii) persecutions at land and iii) surprise attacks under water. We identified a bird a ssemblage ass ociated to predation events, dominated by Macron ectes giganteus.

First breeding record of the northern giant petrel Macronectes halli at Ile Amsterdam

First breeding record of the northern giant petrel <i>Macronectes halli</i> at Ile Amsterdam

Survival in macaroni penguins and the relative importance of different drivers: individual traits, predation pressure and environmental variability.

Understanding the demographic response of free-living animal populations to different drivers is the first step towards reliable prediction of population trends.Penguins have exhibited dramatic declines in population size, and many studies have linked this to bottom-up processes altering the abundance of prey species. The effects of individual traits have been considered to a lesser extent, and top-down regulation through predation has been largely overlooked due to the difficulties in empirically measuring this at sea where it usually occurs.For 10 years (2003–2012), macaroni penguins (Eudyptes chrysolophus) were marked with subcutaneous electronic transponder tags and re-encountered using an automated gateway system fitted at the entrance to the colony. We used multistate mark–recapture modelling to identify the different drivers influencing survival rates and a sensitivity analysis to assess their relative importance across different life stages.Survival rates were low and variable during the fledging year (mean = 0·33), increasing to much higher levels from age 1 onwards (mean = 0·89). We show that survival of macaroni penguins is driven by a combination of individual quality, top-down predation pressure and bottom-up environmental forces. The relative importance of these covariates was age specific. During the fledging year, survival rates were most sensitive to top-down predation pressure, followed by individual fledging mass, and finally bottom-up environmental effects. In contrast, birds older than 1 year showed a similar response to bottom-up environmental effects and top-down predation pressure.We infer from our results that macaroni penguins will most likely be negatively impacted by an increase in the local population size of giant petrels. Furthermore, this population is, at least in the short term, likely to be positively influenced by local warming. More broadly, our results highlight the importance of considering multiple causal effects across different life stages when examining the survival rates of seabirds.

Foraging zones of the two sibling species of giant petrels in the Indian Ocean throughout the annual cycle: implication for their conservation

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 499:233-248 (2014) - DOI: https://doi.org/10.3354/meps10620 Foraging zones of the two sibling species of giant petrels in the Indian Ocean throughout the annual cycle: implication for their conservation Laurie Thiers1,*, Karine Delord1, Christophe Barbraud1, Richard A. Phillips2, David Pinaud1, Henri Weimerskirch1 1Centre d’Études Biologiques de Chizé, Centre National de la Recherche Scientifique, 79360 Villiers en Bois, France 2British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK *Corresponding author: thiers@cebc.cnrs.fr ABSTRACT: We studied the year-round distribution and at-sea activity patterns of the sibling species, northern giant petrel Macronectes halli and southern giant petrel M. giganteus. Loggers combining light-based geolocators and immersion sensors were used to provide year-long data on large-scale distribution and activity of both species from the Crozet Islands (46°25’S, 51°51’E) and northern giant petrels from the Kerguelen Islands (49°19’S, 69°15’E) in the southern Indian Ocean. Argos platform transmitter terminals (PTTs) were used to track fine-scale movements of breeding adults and juveniles. Overall, adults remained within the Indian Ocean during and outside the breeding season, whereas juveniles dispersed throughout the Southern Ocean. In accordance with previous studies, differences in adult distribution and behaviour were greater between sexes than species: females dispersed more widely than males and also spent more time sitting on the water, particularly during the winter. Observed differences in distribution have important conservation implications: adults, especially males, overlap to a large extent with longline fisheries for Patagonian toothfish Dissostichus eleginoides in shelf areas within national Exclusive Economic Zones (EEZs), whereas adult females and juveniles are more likely to encounter high-sea longline fleets targeting tuna in subtropical waters. The circumpolar wide ranging behavior of naïve juvenile birds makes them particularly susceptible to interaction with a wide range of longline fisheries. KEY WORDS: Year-round distribution · Giant petrels · Telemetry · Global location sensing · Longliners Full text in pdf format Supplementary material PreviousNextCite this article as: Thiers L, Delord K, Barbraud C, Phillips RA, Pinaud D, Weimerskirch H (2014) Foraging zones of the two sibling species of giant petrels in the Indian Ocean throughout the annual cycle: implication for their conservation. Mar Ecol Prog Ser 499:233-248. https://doi.org/10.3354/meps10620 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 499. Online publication date: March 03, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Role of wing morphing in thrust generation

In this paper, we investigate the role of morphing on flight dynamics of two birds by simulating the flow over rigid and morphing wings that have the characteristics of two different birds, namely the Giant Petrel and Dove Prion. The simulation of a flapping rigid wing shows that the root of the wing should be placed at a specific angle of attack in order to generate enough lift to balance the weight of the bird. However, in this case the generated thrust is either very small, or even negative, depending on the wing shape. Further, results show that morphing of the wing enables a significant increase in the thrust and propulsive efficiency. This indicates that the birds actually utilize some sort of active wing twisting and bending to produce enough thrust. This study should facilitate better guidance for the design of flapping air vehicles.

Antarctic Site Inventory breeding bird survey data, 1994–2013

AbstractThis data set represents the accumulation of 19 years of seabird population abundance data collected by the Antarctic Site Inventory, an opportunistic vessel‐based monitoring program surveying the Antarctic Peninsula and associated sub‐Antarctic Islands. This Data Paper, which includes 1124 records from 113 locations for seven species of seabirds (Adélie Penguin [Pygoscelis adeliae], Gentoo Penguin [P. papua], Chinstrap Penguin [P. antarctica], Macaroni Penguin [Eudyptes chrysolophus], Blue‐eyed Shag [Phalacrocorax atriceps], Kelp Gull [Larus dominicanus], and Southern Giant Petrel [Macronectes giganteus]), includes data already published by the Antarctic Site Inventory as well as seven years of recent data not previously published. Census data represent a mix of nest and chick counts; each census record includes the location, date, and precision of the census count, along with any auxiliary notes. Included with the database are maps to clarify the location of specific breeding populations that may be new (and thus not previously reported) or ambiguous. This compilation represents the best single source of raw data on the spatiotemporal dynamics of the Pygoscelis penguins in the Antarctic Peninsula region and provides population data on several flying bird species less frequently studied.

Corticosterone mediated costs of reproduction link current to future breeding

Life-history theory predicts that costs are associated with reproduction. One possible mediator of costs involves the secretion of glucocorticoid hormones, which in birds can be measured in feathers grown during the breeding period. Glucocorticoids mediate physiological responses to unpredictable environmental or other stressors, but they can also function as metabolic regulators during more predictable events such as reproduction. Here we show that corticosterone (“Cort”) in feathers grown during the breeding season reflects reproductive effort in two Antarctic seabird species (giant petrels, Macronectes spp.). In females of both species, but not males, feather Cort (“fCort”) was nearly 1.5-fold higher in successful than failed breeders (those that lost their eggs/chicks), suggesting a cost of successful reproduction, i.e., high fCort levels in females reflect the elevated plasma Cort levels required to support high metabolic demands of chick-rearing. Successful breeding also led to delayed moult prior to winter migration. The fCort levels and pre-migration moult score that we measured at the end of current breeding were predictive of subsequent reproductive effort in the following year. Birds with high fCort and a delayed initiation of moult were much more likely to defer breeding in the following year. Cort levels and the timing of moult thus provide a potential mechanism for the tradeoff between current and future reproduction.

Population trends and breeding success of albatrosses and giant petrels at Gough Island in the face of at-sea and on-land threats

AbstractSeveral factors threaten populations of albatrosses and giant petrels, including the impact of fisheries bycatch and, at some colonies, predation from introduced mammals. We undertook population monitoring on Gough Island of three albatross species (Tristan albatross Diomedea dabbenena L., sooty albatross Phoebetria fusca Hilsenberg, Atlantic yellow-nosed albatross Thalassarche chlororhynchos Gmelin) and southern giant petrels Macronectes giganteus (Gmelin). Over the study period, numbers of the Critically Endangered Tristan albatross decreased at 3.0% a year. Breeding success for this species was low (23%), and in eight count areas was correlated (r2 = 0.808) with rates of population decline, demonstrating chick predation by house mice Mus musculus L. is driving site-specific trends and an overall decline. Numbers of southern giant petrels were stable, contrasting with large increases in this small population since 1979. Significant population declines were not detected for either the Atlantic yellow-nosed or sooty albatross, however, caution should be applied to these results due to the small proportion of the population monitored (sooty albatross) and significant interannual variation in numbers. These trends confirm the Critically Endangered status of the Tristan albatross but further information, including a more accurate estimate of sooty albatross population size, is required before determining island wide and global population trends of the remaining species.

Populations of breeding birds in Byers Peninsula, Livingston Island, South Shetland Islands

AbstractData about breeding populations of birds in the Antarctica are rare and fragmented. Thus, information about the status of the breeding populations of Antarctic birds is crucial given the current scenario of climate change, which is particularly acute in Antarctica. This paper presents new information about the populations of the Antarctic tern Sterna vittata, the kelp gull Larus dominicanus, the southern giant petrel Macronectes giganteus, the Antarctic skua Catharacta antarctica lonnbergi, the chinstrap penguin Pygoscelis antarctica and the gentoo penguin Pygoscelis papua on Byers Peninsula (Livingston Island, South Shetland Islands). We used line transects counts to estimate both densities and numbers of nests of the different species. We estimate that there are 398.96 birds km-2 of southern giant petrels (2793 individuals), 62.4 birds km-2 of Antarctic tern (3746 individuals) and 269.1 birds km-2 of kelp gull (1884 individuals). Furthermore, we found 15 nests of Antarctic skua in 25 km2, from which we can estimate that 60–91 birds must breed on Byers Peninsula. We also censused two colonies of gentoo penguins (3000 and 1200 pairs) and 50 pairs of chinstrap. Compared to previous estimates, gentoo penguins seem to have increased whereas chinstrap penguin have decreased. Finally, the populations of Antarctic tern, southern giant petrel and kelp gull have stabilized or slightly increased.

Giant petrels as predators of albatross chicks

Giant petrels Macronectes spp. are not thought to be important predators of albatross chicks, although they are known to kill pre-fledging Thalassarche and Phoebetria albatrosses. We report the first records of predation of healthy great albatross Diomedea spp. chicks, killing wandering albatrosses D. exulans at night on sub-Antarctic Marion Island. Breeding success of this species has decreased markedly in the area where attacks occurred, suggesting that giant petrel predation events are a recent phenomenon. Mouse attacks on wandering albatross chicks may have contributed to the development of this hunting technique. We also report the first observations of giant petrel predation on pre-fledging grey-headed albatross T. chrysostoma chicks as well as additional records of sooty albatross P. fusca chicks being targeted. Only adult northern giant petrels M. halli have been confirmed to kill albatross chicks on Marion Island. Given the threatened status of wandering albatrosses, and the importance of Marion Island for this species, monitoring of their breeding success is necessary to assess whether the predation of chicks by giant petrels spreads around the island.