Holocene Adélie penguin diet in Victoria Land,Antarctica

Ornithogenic soils (N = 97) dated up to 7000 Before Present (bp) were sampled in 16 relict and modern breeding colonies of Adélie penguin along the Victoria Land coast (Ross Sea, Antarctica). Taxonomic identification of fish otoliths (N = 677) recovered in these soils allowed to identify the Antarctic silverfish as the most eaten prey (90.1%) throughout the investigated period. A morphometric analysis of the otoliths revealed that the Adélie penguin primarily selected prey averaging 67.23 ± 23 mm of standard length. Temporal distribution of Pleuragramma antarcticum showed a peak between 2,000 and 4,000 years bp, a period corresponding to the maximum spread of Adélie penguin in the Victoria Land. Possible explanations of the variations of the abundance of the fish prey in the diet are discussed in the context of the paleoclimatic events and as possible consequences of dietary shifts due to the temporal variation of prey availability in the Ross Sea ecosystem.     

Community structure of pelagic cnidarians off Adélie Land, East Antarctica, during austral summer 2008

Some studies have suggested that pelagic cnidarians are important components of the Southern Ocean ecosystem due to their high abundance and diversity and their high predatory effects, although little information on these animals is available. Thus, we examined the spatial distribution of pelagic cnidarians from the oceanic to neritic zone off Adélie Land, East Antarctica. Discrete depth sampling was conducted from the surface to 2,000 m depth from late January to early February 2008. In total, 3347 individuals representing 45 species/taxa from eight orders were collected. Cluster analysis revealed three major clusters: (1) an epipelagic group in the oceanic zone composed mainly of Pegantha martagon, the abundance and species diversity of which were very low; (2) a meso- and bathy-pelagic group characterised by high abundance and species diversity with dominance of Dimophyes arctica, Vogtia serrata, and Halicreas minimum; and (3) a neritic group represented by a high abundance of Diphyes antarctica. Cnidarian communities in the epipelagic zone were divided by hydrographic structures such as the Southern Boundary of the Antarctic Circumpolar Current and Antarctic Slope Front, whereas those in the meso- and bathy-pelagic layers dominated by circumpolar deep water were relatively stable with higher diversity throughout the oceanic zone.     

An albinistic Adélie penguin breeding at Amundsen Bay, Antarctica

An albinistic penguin of Pygoscelis adeliae, found in the colony located in the southwestern part of the Mt. Riiser-Larsen area, Amundsen Bay, Enderby Land, was incubating a single egg. Accepted: 18 September 1999     

Changes in Adélie penguin breeding populations in Lützow-Holm Bay, Antarctica, in relation to sea-ice conditions

The Adélie penguin, Pygoscelis adeliae, an important component of the Antarctic marine ecosystem, is closely associated with sea ice. Using data collected by Japanese Antarctic Research Expeditions since the 1960s, we examined trends in breeding populations of this species around Lützow-Holm Bay. Ten colonies ranging in size from 10 to 2,500 individuals were counted along the Soya Coast. Populations fluctuated synchronously, and overall increased at most colonies, except for two: one located deep inside the bay and another where human disturbance was substantial. Populations tended to increase during, or after, periods of sparse sea ice in summer, a condition that occurred once every decade. An increase in population size also occurred 5 years after a winter of extensive sea ice and after a winter of especially reduced sea ice.     

Stable isotopes reveal Holocene changes in the diet of Adélie penguins in Northern Victoria Land (Ross Sea, Antarctica)

Adélie penguin (Pygoscelis adeliae) modern and fossil eggshells and guano samples collected from ornithogenic soils in Terra Nova Bay (Victoria Land, Ross Sea) were processed for carbon and nitrogen isotopic ratios with the aim of detecting past penguin dietary changes. A detailed and greatly expanded Adélie penguin dietary record dated back to 7,200 years BP has been reconstructed for the investigated area. Our data indicate a significant dietary shift between fish and krill, with a gradual decrease from past to present time in the proportion of fish compared to krill in Adélie penguin diet. From 7,200 to 2,000 years BP, δ¹³C and δ¹⁵N values indicate fish as the most eaten prey. The dietary contribution of lower-trophic prey in penguin diet started becoming evident not earlier than 2,000 years BP, when the δ¹³C values reveal a change in the penguin feeding behavior. Modern eggshell and guano samples reveal a major dietary contribution of krill but not a krill-dominated diet, since δ¹³C values remain much too high if krill prevail in the diet. According to the Holocene environmental background attested for Victoria Land, Adélie penguin dietary shifts between fish and krill seem to reflect penguin paleoecological responses to different paleoenvironmental settings with different conditions of sea-ice extension and persistence. Furthermore, Adélie penguin diet appears to be particularly affected by environmental changes in a very specific period within the breeding season, namely the egg-laying period when penguin dietary and feeding habit shifts are clearly documented by the δ¹³C of eggshell carbonate.     

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 Adélie 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 Adélie 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. Accepted: 28 August 1998     

Weather,microclimate, and energy costs of thermoregulation for breeding Adélie Penguins

Summary We measured meteorological conditions and estimated the energy costs of thermoregulation for young and adult Adélie Penguins (Pygoscelis adeliae) at a breeding colony near the Antarctic Peninsula. Air temperatures averaged < 5°C and strong winds were frequent. Operative temperatures (T_e) for adults ranged from –8 to 28°C, averaging 5–6°C, for the period from courtship to fledging of chicks. The average energy cost of thermoregulation (C_th) for adult penguins was equivalent to 10–16% of basal metabolism. C_th comprised about 15% of the estimated daily energy budget (DEB) of incubating adults, but only about 1% of the DEB of adults feeding chicks. The T_e's for chicks older than 14 days ranged from 0 to 31°C, averaging 8.0 C. The C_th for downy chicks ranged from about 31% of minimal metabolic rate (MMR) in 1 kg chicks to about 10% of MMR in 3 kg chicks. Between initial thermal independence (age 12–14 days) and the cessation of parental feeding (age 35–40 days), chicks use about 10–11% of assimilated energy for thermoregulation. C_th is equivalent to about 17% of the MMR of fledglings during their 2–3 week fast. We observed no indication of thermal stress (i.e., conditions in which birds cannot maintain stable T_b) in adults and no indication of cold stress in any age class. However, on clear, calm days when air temperature exceeds 7–10°C for several hours, downy chicks are vulnerable to lethal hyperthermia.     

Euphausia superba dominates in the diet of Adélie penguins feeding under fast sea-ice in the shelf areas of Enderby Land in summer

Adélie penguins Pygoscelis adeliae in Enderby Land, Antarctica feed mainly on Euphausia superba during the chick rearing season in shelf areas where fast sea-ice remains: indicating that E. superba is abundant under the fast sea-ice in these areas. The shelf areas in Enderby Land, therefore, are unique since the previous studies of Adélie penguin diet in Ross Sea, Adélie Land and Prydz Bay show that E. crystallorophias is the most abundant krill species in shelf areas in general.     

Sea ice affects the population dynamics of Adélie penguins in Terre Adélie

Overall Adélie penguin population size in Pointe Géologie Archipelago increased between 1984 and 2003 at a rate of 1.77% per year, and averaged 33,726±5,867 pairs. As predicted by the optimum model proposed by Smith et al. (Bioscience 49:393–404, 1999). Adélie penguin population size increased when sea ice extent and concentration (SIE and SIC) decreased six years earlier, indicating that the conditions around reproduction or first years at sea, were determinant. The breeding success averaged 85.2±35.45% and was not related to environmental variables. Adult survival probability varied between years from 0.64 to 0.82. Southern oscillation index (SOI) had a strong negative effect on adult annual survival. Adult survival of Adélie penguins increased during warmer events, especially during winter and spring at the beginning of reproduction. Therefore, we speculate that the rapid decreases in 1988–1991 and 1996 of the breeding population size were related to a decrease in adult mortality. However, adult survival varied little, and could not explain the strong increasing population trend. The sea ice conditions during breeding or during the first year at sea appeared determinant and influenced the population dynamics through cohort effects, probably related to the availability of productive feeding habitats.     

Satellite tracking of Adélie penguins

Summary Female Adélie penguins (Pygoscelis adeliae) that take too long on their first post-laying foraging trip are a major cause of breeding failure, but in the ice-filled waters of Antarctica, determining where they go and why they are away so long has proved difficult. Here we describe the first successful attempt to track penguins at sea using satellite telemetry. Four females foraged in different locations, dispelling the notion of a common feeding ground. They moved up to 272 km from the rookery and covered from 551 to 1,121 km on their trips, swimming at minimum average speeds around 1.2 m/s. The birds were most likely to be in the water between 0630 and 1430 when light intensity, important for a visual predator, was greatest. Carrying the transmitters reduced rates of fat deposition (weight gain), increasing the duration of foraging trips of females, and suggested that they may forage until their fat depots reach a minimum threshold level. This has two implications: (i) durations of these postlaying foraging trips could potentially be used as an indicator of krill abundance (Euphausia sp), the almost exclusive food of Adélie penguins during this period, and (ii) any reduction in krill stocks caused by harvesting could increase foraging trip durations with a concomitant increase mi breeding failures.     

People in Antarctica — how much do Adélie Penguins Pygoscelis adeliae care?

Summary In the course of physiological field studies, we opportunistically examined the effects of humans and aircraft on breeding Adélie Penguins Pygoscelis adeliae. Proximity to both aircraft and humans caused substantial increases in penguin heart rate even when no external stress was manifest. A solitary human at 20 m distance from commuting penguins on a well-used pathway caused the birds to deviate by 70 m. Birds at nests exposed to a single human fled much more readily when the brood consisted of large chicks (critical distance 6.1 m) rather than small chicks (critical distance 1.3 m) or eggs (critical distance 0.3 m). Aircraft caused birds to panic at distances greater than 1,000 m and 3 days exposure to a helicopter inhibited birds that had been foraging from returning to their nests, caused bird numbers in the colonies to decrease by 15% and produced an active nest mortality of 8%. Based on this data, we make recommendations to minimize stress on Adélie Penguin colonies exposed to man.     

Synchronous diving behavior of Adélie penguins

Synchronizing behavior with other conspecifics has been suggested as serving a function of increased foraging efficiency. However, the potential costs associated with synchronization of behavior have rarely been studied. Adélie penguins Pygoscelis adeliae sometimes dive synchronously in small open waters surrounded by fast sea ice. We examined the diving behavior of three couples and one trio, which were observed to dive synchronously among groups of 12–47 birds for 1.7–4.5 h duration, with time-depth recorders. Timing of diving and surfacing differed slightly between individuals, and one bird tended to initiate diving earlier than the other. Although the duration of the dives differed only slightly between these birds, the maximum depth of the dives differed to a large extent, with one member tending to dive consistently deeper than the other bird in two out of the four cases. Vertical distances between tagged birds in the undulatory phases of the dives (presumed feeding time) were greater than those in the descent and ascent phases, suggesting independent foraging by group members. Duration of the undulatory phase of the dives tended to be shorter in deeper-diving individuals than the others in the synchronously diving group, suggesting a potential cost of reduced feeding time to synchronize diving and surfacing with other birds. A digital video image relating to the article is available at .     

Biological characteristics of euphausiids preyed upon by Adélie penguins in relation to sea-ice conditions in Lützow-Holm Bay,Antarctica

We examined the biological characteristics of euphausiids found in the stomachs of Adélie penguins in relation to sea-ice conditions in Lützow-Holm Bay over three seasons. Euphausiids, especially Euphausia superba, proved to be a staple food for Adélie penguins irrespective of the ice condition. Body length and maturity-stage compositions of euphausiids were different among seasons, probably reflecting sea-ice condition in summer. The mean body length decreased and maturity regressed during each season in E. superba, which was partly attributable to the selective feeding on large, mature female krill by Adélie penguins. The 1995/1996 year class of E. superba, which was spawned when the sea ice was most developed, was strong and conspicuous in the 1996/1997 and 1997/1998 seasons. This vigor indicates that sea ice provided females with good spawning conditions and larvae with good growth and survival rates.     

The gastrointestinal tract of Adélie penguins – morphology and function

The aim of this study was to provide data on the morphology of the gastrointestinal tract of Adélie penguins (Pygoscelis adeliae). It was found to consist of a long oesophagus, a two-chambered stomach, a small intestine measuring only 5.22body length, two rudimentary caeca and a short colon, typical of carnivorous birds. The stomach comprised a glandular proventriculus and a muscular gizzard that frequently contained grit. An acidic pH was recorded in both chambers. Ultrastructural studies of the small intestinal mucosal membrane revealed epithelial cells with elongated, irregular microvilli and high affinity for toluidine blue, absorptive intestinal epithelial cells and goblet cells. Numerous large lymphocyte-like cells were observed close to the brush border of the epithelium, and empty spaces on the epithelial surface reflected normal cell loss in the small intestine. The rudimentary caeca and colon provide relatively little volume and time for symbiotic bacteria to aid the digestion of crustacean chitin.     

Intra-seasonal variation in foraging behavior among Ad��lie penguins (Pygocelis adeliae) breeding at Cape Hallett, Ross Sea, Antarctica

We investigated intra-seasonal variation in foraging behavior of chick-rearing Adélie penguins, Pygoscelis adeliae, during two consecutive summers at Cape Hallett, northwestern Ross Sea. Although foraging behavior of this species has been extensively studied throughout the broad continental shelf region of the Ross Sea, this is the first study to report foraging behaviors and habitat affiliations among birds occupying continental slope waters. Continental slope habitat supports the greatest abundances of this species throughout its range, but we lack information about how intra-specific competition for prey might affect foraging and at-sea distribution and how these attributes compare with previous Ross Sea studies. Foraging trips increased in both distance and duration as breeding advanced from guard to crèche stage, but foraging dive depth, dive rates, and vertical dive distances travelled per hour decreased. Consistent with previous studies within slope habitats elsewhere in Antarctic waters, Antarctic krill (Euphausia superba) dominated chick meal composition, but fish increased four-fold from guard to crèche stages. Foraging-, focal-, and core areas all doubled during the crèche stage as individuals shifted distribution in a southeasterly direction away from the coast while simultaneously becoming more widely dispersed (i.e., less spatial overlap among individuals). Intra-specific competition for prey among Adélie penguins appears to influence foraging behavior of this species, even in food webs dominated by Antarctic krill.     

Ontogeny of hepatic microsomal 3-hydroxylation of quinine in Adélie Penguins

Ontogeny of hepatic cytochrome P450 (CYP) content and of quinine 3-hydroxylation, a biomarker of human CYP3A activity, was investigated in Adélie Penguins (Pygoscelis adeliae) by comparing liver microsomes from chicks aged 13-28 days (n=10) with those from adults. The total CYP content in chick microsomes was significantly lower than in adults and correlated with the age of the chicks (r=0.894, P<0.001). Kinetic parameters (mean+/-S.D.) for quinine 3-hydroxylation in chick microsomes were lower than the corresponding values in adult penguins (Km, 122+/-27 vs. 160+/-73 microM; Vmax, 119+/-35 vs. 160+/-72 pmol/min/mg protein) but the differences were not significant, and neither Km nor Vmax correlated with age of the chicks. The pattern of inhibition of quinine 3-hydroxylation by specific human CYP inhibitors suggests that the CYP enzyme mediating quinine 3-hydroxylation in penguin chicks is similar to human CYP3A, but is a different isoform from that in adult penguins. The results imply that Adélie Penguin chicks may have a different susceptibility to environmental pollutants from adult penguins.     

Sex differences in Adélie penguin foraging strategies

Consistent sex differences in foraging trip duration, feeding locality and diet of breeding Adélie penguins (Pygoscelis adeliae) were demonstrated at two widely separated locations over several breeding seasons. Differences in foraging behaviour were most pronounced during the guard stage of chick rearing. Female penguins made on average longer foraging trips than males, ranged greater distances more frequently and consumed larger quantities of krill. In contrast, males made shorter journeys to closer foraging grounds during the guard period and fed more extensively on fish throughout chick rearing. Mean guard stage foraging trip durations over four seasons at Béchervaise Island, Eastern Antarctica and over two seasons at Edmonson Point, Ross Sea ranged between 31 and 73 h for females and 25 and 36 h for males. Ninety percent of males tracked from Béchervaise Island by satellite during the first 3 weeks post-hatch foraged within 20 km of the colony, while the majority (60%) of females travelled to the edge of the continental shelf (80–120 km from the colony) to feed during this period. Received: 10 December 1997 / Accepted: 10 April 1998     

Chick provisioning and breeding success of Adélie penguins at Béchervaise Island over eight successive seasons

Data on foraging trip durations and meal sizes were collected by means of an automated monitoring system from breeding Adélie penguins (Pygoscelis adeliae) at Béchervaise Island over eight breeding seasons, commencing in 1991-92. Significant interannual differences in duration of foraging trips, meal sizes and diet composition were observed. These parameters were correlated with breeding success and fledging masses, and provide useful indicators of food availability during the breeding season. Chicks were particularly vulnerable to a decreased availability of food during the first 3 weeks after hatching.     

Human-induced behaviour in Adélie penguins Pygoscelis adeliae

Summary Adélie penguins Pygoscelis adeliae appear to be little perturbed by man. We examined the incidence of nest desertion and duration of foraging trip in Adélie penguins when manipulated and fitted with devices of differing sizes. Birds with ca. 1 cm clipped from their tail feathers stayed at sea 50% longer than unmarked controls. The length of foraging trip and incidence of nest desertion increased with increasing device volume. Penguins fitted with devices did not reduce foraging trip length to that of unpackaged birds for at least 19 days. The susceptibility of Adélie penguins to disturbance should be carefully considered when activity patterns are being studied.