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To monitor the rapid changes occurring in Arctic ecosystems and predict their direction, basic information about the current number and structure of the main components of these systems is necessary. Using boat-based surveys, we studied the numbers and distribution of seabirds foraging in Hornsund (SW Spitsbergen) during three summer seasons. The average number of seabirds foraging concurrently in the whole fjord was estimated at 28,000. Little Auks Alle alle were the most numerous, followed by Northern Fulmars Fulmarus glacialis, Brünnich's Guillemots Uria lomvia and Black-legged Kittiwakes Rissa tridactyla. The pelagic zone was exploited by some 75% of the birds. Their density was the highest (> 400 ind. km−2) in the tidewater glacier bays, where kittiwakes were predominant, and the lowest in the coastal glacier bays. The seabirds in Hornsund daily consumed c. 12.7 tons of food, i.e. c. 0.2% of the summer mesozooplankton and fish standing stocks available in the fjord. This food consisted primarily of copepods, amphipods and molluscs (c. 70%), whereas fish made up < 15%. More than 50% of this biomass was ingested by pursuit divers, while surface feeders took c. 29% and benthophages c. 13%. About three-quarters of the food biomass was taken from the pelagic zone. This paper describes, for the first time in quantitative terms, the structure and function of a seabird community foraging in an Arctic fjord. It also provides a baseline for future studies on climate-induced changes in the importance of seabirds in the Arctic food web. [ABSTRACT FROM AUTHOR]

The ivory gull Pagophila eburnea is an Arctic seabird species whose distribution is tightly coupled to the availability of sea ice. During the last decades, strong declines have been reported for breeding colonies in Canada and Greenland, which are usually located on nunataks or remote coastal islands. Here, we report the observation of a colony of ivory gulls breeding on a gravel-covered iceberg 70 km off Northeast Greenland in August 2014. It concerned approximately 60 adults, including two ringed individuals, and many chicks. This represents an unusual breeding site for the species, to be compared with a few cases of colonies on gravel-covered sea ice. Breeding on an offshore iceberg may be advantageous since it provides ultimate protection from predators. Furthermore, the proximity to the productive North East Water polynya may have been attractive to these gulls. As a consequence of this and previous observations, colony surveys should not solely focus on inland and coastal breeding habitats, but should be extended towards the ocean. [ABSTRACT FROM AUTHOR]

Phenology, the study of stages within the life cycles of plants and animals, has served as a proxy for weather and climate throughout human history, but has only recently become its own field of environmental science. Phenological constraints are particularly demanding in avian species because of the necessity of matching chick provisioning with high food abundance, while allocating time for migration. Within avian species, seabird phenology is of particular interest because many seabird species exhibit colonial breeding behaviour. Penguins, representing roughly 90 % of the biomass in the Southern Ocean, are well studied in the context of population dynamics, prey abundance, and phenology. Here I review the annual cycles of Pygoscelis penguins, a genus including gentoo ( Pygoscelis papua), chinstrap ( Pygoscelis antarctica), and Adélie ( Pygoscelis adeliae) penguins, to better understand what is known about their phenology, what causes known changes, and how their phenology influences fitness. Major differences exist between species, particularly in relation to winter migration, incubation shifts, and the timing of breeding. Even with the numerous studies examining phenology in Pygoscelis penguins, large gaps in our understanding of plasticity in the annual cycle remain. In particular, certain phases are neglected because they are logistically difficult to record or have erroneously been ignored. In addition, temporally, large gaps exist in our understanding of phenology, where studies have not been updated in over 20 years at a particular field site. Because phenology does vary greatly between years, depending on the colony, when possible, researchers should strive to update phenological records by recording the dates of phases each year. [ABSTRACT FROM AUTHOR]

The first aim of our long-term study on the at-sea distribution of the upper trophic levels-seabirds and marine mammals-in polar marine ecosystems is to identify the main factors affecting their distribution: water masses and pack ice, fronts and ice edge as defined on the basis of water temperature, salinity and ice overage. In this study, seabird at-sea distribution was determined in the south-eastern Atlantic Ocean in summer along four return transects between Cape Town, South Africa, and Queen Maud Land, Antarctica: two on board icebreaking MS Ivan Papanin and two on board icebreaking RV Polarstern between December 2007 and January 2012. During a total of 1,930 half-an-hour transect counts devoted to seabird recording, 69,000 individuals were encountered, belonging to 57 species (mean: 36 individuals per count, all species and expeditions pooled). In comparison, the adjacent Weddell Sea shows a lower seabird biodiversity (30 species and 150 individuals per count) than in the area covered by this study. European Arctic seas reflect an intermediate biodiversity, with 30 species and 60 individuals per count; the major difference is observed in closed pack ice, almost empty in the Arctic but showing a very high biomass in the Antarctic. On the other hand, following the same route in different years allowed to compare results: density and abundance were found to be homogenous and reproducible between years for some species, while very important patchiness was detected for others, causing large heterogeneities and differences between expeditions. [ABSTRACT FROM AUTHOR]

The crucial role of seabirds in the enrichment of nutrient-poor polar terrestrial ecosystem is well-known. However, no studies have examined the potentially different impacts associated with piscivorous and planktivorous bird colonies on the surrounding tundra soils. Therefore, we compared guano deposition and physical and chemical parameters of soil near two large seabird colonies, one of planktivorous little auks ( Alle alle) and the other comprising piscivorous Brunnich's guillemots ( Uria lomvia) and kittiwakes ( Rissa tridactyla). The two colonies generated similar levels of guano deposition, with the intensity of deposition decreasing away from the colony. Guano deposition adjacent to both colonies was considerably higher than that in control areas. The increased guano supply around colonies significantly enhanced soil conductivity, nitrogen (NO, NH), potassium (K), and phosphate (PO) ion concentrations and led to reduced pH values. Guano deposition explained 84 % (piscivorous colony) and 67 % (planktivorous colony) of the total variation in the tested soil parameters. Planktivore and piscivore colonies affected adjacent tundra in different ways. The phosphate content and pH value of soil influenced by piscivores were significantly higher than values measured in planktivore-influenced soil. The gradient of guano deposition and associated ion content in the soil decreased more rapidly with distance from the piscivore colony. Climate-induced changes in populations of planktivorous and piscivorous seabirds are expected in the study region and may therefore have substantial consequential effects on Arctic terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

Colonial breeding is common in seabirds, and may provide individuals with benefits such as increased protection from predators by joint defence, improved information exchange and enhanced access to mates. However, the presence of large numbers of individuals in breeding colonies may also lead to interference, especially where conspecific behaviour disrupts the normal chick-rearing routine. Using standardised video recordings, we describe and quantify for the first time such disruptive behaviour by conspecifics in penguins. This disruptive behaviour appeared to be common in chick-feeding Southern rockhopper penguins Eudyptes chrysocome and its occurrence did not differ significantly among the colony areas where observations were made. Females were commonly (77 % of 111 observation sessions) disrupted by other adults when attempting to feed chicks alone during the crèche stage. They consequently reduced the time spent with their chicks. Disrupted chicks compensated by begging more intensely when their female parents were present, and they did not eat significantly less often than undisrupted chicks. In contrast, disruptive behaviour towards chick-feeding males or pairs was never observed. This study supplements knowledge about a disruptive behaviour that appears to be common but for which the function remains unclear in penguins, as the intruders did not appear to gain any visible benefits. [ABSTRACT FROM AUTHOR]

In the frame of our long-term study of the distribution of seabirds and marine mammals in polar seas, observers from this team participated in the European Arctic expeditions of icebreaking RV Polarstern during summer 2008. The main aims were to obtain more information on the mechanisms underlying the at-sea distribution of the 'higher trophic levels' and to detect possible temporal and spatial changes in numbers, especially in function of climatic changes and decreasing ice coverage in the Arctic. In total, 1,175 half-an-hour transect counts were devoted to seabird and marine mammal distribution in the Greenland and Norwegian Seas, from 14 June to 15 August, 2008. A major feeding ground for cetaceans and seabirds was detected in the south-western Greenland Sea and the Denmark Strait in the Polar Front between Polar and Arctic Water masses. For the main cetacean and seabird species, almost all individuals recorded during the whole expedition were encountered in this limited zone of 33 counts: 135 humpback whales Megaptera novaeangliae and 1,940 common guillemots Uria aalge. Moreover, 4,400 fulmars Fulmarus glacialis light morph were observed in this zone, i.e . close to half of the total. All were actively feeding, making this zone the major feeding ground for the higher trophic levels in the European Arctic Seas and so confirming the great importance of fronts (upwellings) for the biological productivity of the oceans. Such data are essential for a successful conservation and management of the Denmark Strait and adjacent areas. [ABSTRACT FROM AUTHOR]

Marine birds are important predators in the marine ecosystem, and dietary studies can give useful information about their feeding ecology, food webs and oceanographic variability. The aim of this study was to increase our understanding of the diet and trophic level of the seabirds breeding in Kongsfjorden, Svalbard. We have used fatty acids and stable isotopes, both of which integrate diet information over space and time, to determine trophic relationships in marine food webs. Fatty acid compositions of muscle from Little auk ( Alle alle), Brünnich's guillemot ( Uria lomvia), Black-legged kittiwake ( Rissa tridactyla), Northern fulmar ( Fulmarus glacialis) and Glaucous gull ( Larus hyperboreus) were determined and compared with their prey species. Canonical analysis (CA) showed that fatty acid composition differed among the five seabird species. Little auk, Black-legged kittiwake and Northern fulmar had high levels of the Calanus markers 20:1n9 and 22:1, indicating that these seabirds are a part of the Calanus food chain. Brünnich's guillemot differed from the other species with much lower levels of 20:1n9 and 22:1. Brünnich's guillemot is a pursuit diver feeding on fish and amphipods deeper in the water column, below 30 m. Glaucous gull also differed from the other seabird species, with a larger variation in the fatty acid composition indicating a more diverse diet. Trophic level analysis placed Little auk at the lowest trophic level, Brünnich's guillemot and Black-legged kittiwake at intermediate levels and Glaucous gull and Northern fulmar at the highest trophic level. [ABSTRACT FROM AUTHOR]

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 Géologie archipelago (Terre Adélie, 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, Adélie 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 (Adélie 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 (Adélie 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. [ABSTRACT FROM AUTHOR]

We studied the distribution and abundance of seabirds along the Beagle Channel during February and March 1997. We examined the distribution and abundance, following the strip transects methodology, of species and their relation with habitat and foraging strategy of the birds. We divided the study area into six zones a priori. We made 20 trips aboard tourist vessels. The species most abundant in the study area were the imperial cormorant, dolphin gull, kelp gull, black-browed albatross, South American tern and Chilean skua. We concluded that seabirds were distributed non-randomly in the marine environment of the Beagle Channel. The shallow waters present the largest seabird density in the Beagle Channel. The Islas Bridges zone had the highest total density of seabirds, followed by the Bahía Ushuaia zone. The first zone holds colonies of most of the seabird species nesting in the channel. The presence of seabirds in the Bahía Ushuaia zone is influenced by the Islas Bridges zone itself, from where breeding birds come, and also by Ushuaia city, the port and the open garbage dump, where birds that feed on carrion can find alternative sources of food. The distribution of species in the whole study area was related to the foraging strategies, interactions with other species and characteristics of the habitat. We identified three groups of bird species and four independent species by cluster analysis. The first group included the black-browed albatross and the Magellanic penguin, which were associated with deep waters. In the second group the imperial cormorant and Chilean skua were associated with shallow waters along the study area, especially in the Islas Bridges zone where these species breed. Lastly, the kelp gull and southern giant petrel formed interspecific groups on the coast in places influenced by humans. The independent species numbered four. The rock cormorant associated with shallow waters in kelp bed areas. Showing a completely different foraging behaviour from the rest of the species, the dolphin gull occurred in shallow waters in the Islas Bridges zone associated with sea lions' and cormorants' colonies. Diving petrels were associated with deep waters on the west side of the channel. The South American tern was distributed all along the study area. [ABSTRACT FROM AUTHOR]