Gentoo Penguins Pygoscelis Papua Research Articles

Dietary Carotenoid Supplementation Affects Orange Beak but not Foot Coloration in Gentoo Penguins Pygoscelis papua

Abstract Red, orange, and yellow carotenoid-based coloration abounds in birds, with over half of all avian orders known to display it in some form. Penguins (Order Sphenisciformes), however, are one order of birds for which the proximal causation of ornaments is unclear, i.e., whether such colors in plumage or bare-parts are carotenoid-based. We experimentally supplemented the diet of captive Gentoo Penguins Pygoscelis papua for two months with extracts of krill, a common carotenoid-rich food source for these animals in the wild, to determine whether orange coloration in the beak and feet is influenced by carotenoid content of the diet. We found using UV-Vis reflectance spectrophotometry that dietary carotenoid enrichment elevated beak but not foot brightness. This suggests that the crustacean part of the diet is at least in part responsible for orange beak coloration but not feet in Gentoo Penguins and that, like other carotenoid signals, these traits have the potential to reveal important aspects of mat...

Stable isotopes indicate sex-specific and long-term individual foraging specialisation in diving seabirds

An important aspect of foraging ecology is the extent to which different individuals or genders within a population exploit food resources in a different manner. For diving seabirds, much of this information relates either to short-term dietary data or indirect measures such as time budgets. Moreover, dietary specialisation can be difficult to detect due to biases associated with conventional sampling techniques. We used stable isotope ratios in blood and feathers to infer trophic and habitat specialisations among 4 diving seabird taxa — the gentoo penguin Pygoscelis papua, the macaroni penguin Eudyptes chrysolophus, the South Georgian shag Phalacrocorax (atriceps) georgianus and the Kerguelen shag P. (atriceps) verrucosus. This allowed us to investigate foraging specialisation and assess whether social dominance or differences in foraging preferences explained the observed patterns. In all taxa where sexes were known we found that males foraged at a higher trophic level (δ 15 N values) than females, although this was not significant in macaroni penguins. We believe that this is linked to a dual foraging strategy among female macaroni penguins. For South Georgian shags, we found that sex-related dietary differences persisted for long periods (inferred from stable isotope analyses of feathers and blood). We suggest that the trophic differences are driven by differ- ences in physiological performance, with males tending to dive deeper than females because of their larger size, and hence able to access higher trophic level prey items. Moreover, male and female shags tend to forage at different times of day; therefore, social dominance by males is unlikely to be driving the observed differences. We also recorded highly significant relationships between stable isotope signatures in blood (representing the breeding season diet) and those in feathers (mostly rep- resenting the previous non-breeding season diet) in both the South Georgian and Kerguelen shags. This strongly suggests that these 2 taxa include individuals with distinct foraging specialisation (and most probably foraging locations) that are maintained over long periods.

Многолетняя динамика численности пингвина дженту Pygoscelis papua (Forst.) и рост антарктического туризма в районе станции Академик Вернадский

Многолетняя динамика численности пингвина дженту Pygoscelis papua (Forst.) и рост антарктического туризма в районе станции Академик Вернадский

Behaviour and breeding success of gentoo penguins Pygoscelis papua in areas of low and high human activity

A key factor influencing wildlife responses to human activity is the degree to which animals have been previously exposed to human stimuli. On subantarctic Macquarie Island, gentoo penguins Pygoscelis papua breed in areas of high and low human activity (on and off-station, respectively). We investigated the behaviour and breeding success of gentoo penguins on and off-station, by a) comparing the behavioural responses of guarding gentoos before, during and after exposure to standardised pedestrian approaches, and b) employing an observational study to determine how human activity may have contributed to within-season breeding success in light of other environmental and site variables. Behavioural responses to pedestrian visitation by gentoos off-station were significantly stronger than those of birds breeding on-station. However, no relationship was found between pedestrian activity and breeding success off-station. Breeding success was, however, positively related to colony size, and negatively related to the activity of other penguins, the number of nearby southern elephant seal Mirounga leonina harems and the location of colonies within short grassland. On-station, breeding success was amongst the highest recorded for that season. Habituation, predator exclusion and the relevance of these findings for management are discussed.

Polybrominated diphenyl ethers, polychlorinated dibenzo-dioxins,-furans, and-biphenyls in three species of antarctic penguins

Fish-eating seabirds are recognized to be at risk of accumulating toxic contaminants due to their high position in the trophic web and to their low ability to metabolize xenobiotic compounds. Penguins are widely distributed in Antarctica and represent an important fraction of the Antarctic biomass. They feed mainly on krill and, depending on krill availability, also on fish. It has been reported that predators may be a sink for volatile and toxic chemicals and this may pose a serious environmental problem. Polybrominated diphenyl ethers (PBDEs), polychlorinated dibenzo-dioxins (PCDDs), -furans (PCDFs), and -biphenyls (PCBs), including non-ortho congeners, hexachlorobenzene (HCB) and p,p'-DDE, were quantified in three species of Antarctic Pygoscelids in order to evaluate their accumulation patterns. The potential toxicity of twenty-two dioxin-like congeners was assessed and expressed as 2,3,7,8-tetraCDD equivalents (TEQs). Differences between males and females were investigated. Blood samples of the Adélie penguin Pygoscelis adeliae, Chinstrap penguin Pygoscelis antarctica and Gentoo penguin Pygoscelis papua were collected at Admiralty Bay, King George Is (62 degrees 10'39" S, 58 degrees 26'46" W) in February 2004. Halogenated hydrocarbons were identified and quantified using gas chromatography coupled with gas chromatography mass spectrometry analyses. Results are expressed on a wet weight basis. HCB, p,p'-DDE and sigmaPCBs were higher in Adélie penguins (6.7 +/- 6.1, 8.2 +/- 3.3 and 9.8 +/- 3.8 ng/g, respectively) than in Chinstrap and Gentoo penguins, both of which showed values in the same order of magnitude, but approximately 40% lower than Adélie penguins. Hexa-CBs ranged 35-45% of the residue. Low-chlorinated PCBs (nos. 70+76+95+ 56+60+101) accounted for 40-60% in the three species. PCB101 made up 15% of the residue in Adélie penguins. PBDEs were 291 +/- 477, 107 +/- 104 and 116 +/- 108 pg/g in Adélie, Chinstrap and Gentoo penguins, respectively; the most abundant congeners were BDE47 in Adélie and Chinstrap penguins and BDE17 in Gentoo penguins. PCDDs were 22 +/- 32, 6.5 +/- 7.4 and 18 +/- 23 pg/g in Adélie, Chinstrap and Gentoo penguins, respectively. PCDFs were higher in Adélie penguins and lower in Chinstrap penguins. PCDDs/Fs and PBDEs were higher in males than in females of Gentoo and Chinstrap penguins; differences in concentrations were likely related to the partial detoxification that occurs in females during egg formation. Of the four non-ortho PCBs measured, PCB126 occurred at the highest concentrations and contributed the majority of the non-ortho PCB-TEQ in Gentoo and Chinstrap penguins. The highest TEQs were found in the Gentoo penguin and due mainly to PCDDs and non-ortho PCBs. POP concentrations in penguins were lower than those found in seabird species from other areas of the world. Different chemical accumulation patterns were observed in relation to species and sex; the Adélie penguin showed the highest POP levels. Dissimilar ecological or metabolic features may be involved; the diverse timing of reproduction steps can be responsible for those differences; moreover, Adélie penguins feed on krill (a fatty resource) more abundantly than the other two species during the rearing period. The South Shetland Islands might be subjected to a higher chemical impact with respect to the rest of Antarctica, due to their being near South America. Because penguins are fish-eating birds showing low detoxifying capacities and key-species in Antarctic ecosystems, further studies on their xenobiotic metabolism should be carried out.

Geochemical evidence for rapid enlargement of a gentoo penguin colony on Barton Peninsula in the maritime Antarctic

Gentoo penguin Pygoscelis papua is an important component of the Antarctic marine ecosystem. In this paper, we use an indirect approach, a geochemical method combining with 137Cs and 210Pb CRS mode dating, to study the dynamics of the gentoo population and colony on Barton Peninsula, King George Island, in the maritime Antarctic. Five sediment profiles were sampled in the zone between the gentoo penguin colony and tundra vegetation on this peninsula and the sediment sequence and typical elements from penguin guano were analysed. Results showed that the levels for typical elements display a dramatic change at around 5 cm depth, indicating the strong impact of penguin guano. The sediments below 5 cm showed lower concentrations in these elements, suggesting that these sediments had received little impact from penguin guano. By Q-mode factor analysis, a method for decomposing multiple factors, we found that over the past sixty years the gentoo colony showed a rapid enlargement and the tundra vegetation had been destroyed. Possible factors responsible for the enlargement of the penguin colony are tentatively discussed.

Mackerel icefish Champsocephalus gunnari in the diet of upper trophic level predators at South Georgia: implications for fisheries management

The mackerel icefish Champsocephalus gunnari Lonnberg is an important component of the ecosystem at South Georgia. Its diet is dominated by Antarctic krill Euphausia superba; in turn, it is also an important prey of a number of upper trophic level predators, as well as being the target of commercial fisheries. Data on the frequency and size structure of mackerel icefish in the diet of Antarctic fur seals Arctocephalus gazella and gentoo penguins Pygoscelis papua from 1991 to 2002 were used to examine trophic interactions involving this species and to evaluate the potential impact of predators on its population. Mackerel icefish occurred in 10 to 20% of scats from Antarctic fur seals and comprised 48% of the diet by mass of gentoo penguins. The contribution of mackerel icefish to the diet of predators was in inverse proportion to the contribution of Antarctic krill. The length- frequency distributions of mackerel icefish indicated a dominant mode at 130 to 180 mm total length (the 1+ age class), with apparent strong cohorts entering the population in 1993, 1996, 1999 and 2001. Extrapolation of diet data to produce a consumption estimate for the South Georgia population of Antarctic fur seals and gentoo penguins suggests that scientific trawl surveys may underestimate the standing stock of mackerel icefish by 1 order of magnitude. Changes in the South Georgia ecosystem over the past 2 decades may have increased the level of consumption of mackerel icefish by predators, providing a potential ecosystem-based explanation for the lack of a recovery to the pre- exploitation population size.

Foraging under contrasting oceanographic conditions: the gentoo penguin at Kerguelen Archipelago

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 302:245-261 (2005) - doi:10.3354/meps302245 Foraging under contrasting oceanographic conditions: the gentoo penguin at Kerguelen Archipelago Amélie Lescroël*, Charles-André Bost Centre d’Etudes Biologiques de Chizé, CNRS, UPR 1934, 79360 Villiers en Bois, France *Email: lescroel@cebc.cnrs.fr ABSTRACT: Coastal seabirds are bound to be dependent on local marine resources. We hypothesize that the localization of the breeding colony will influence the foraging patterns of such predators. The foraging behavior of gentoo penguins Pygoscelis papua was investigated in contrasting marine environments at Kerguelen Archipelago over the 2002–03 and 2003–04 breeding seasons. Using time-depth recorders (TDRs) and satellite transmitters, we describe the at-sea distribution and diving behavior of gentoo penguins breeding in 2 colonies facing the open sea (Open Sea 1 and Open Sea 2) and 1 colony protected in a closed bay (Closed Sea). The foraging behavior varies extensively across the Kerguelen Archipelago, almost as much as it does over the entire range of the species. Different foraging strategies emerge, depending on the local conditions: large foraging ranges, long trips, long benthic dives on demersal fish at Open Sea colonies versus small foraging ranges, short trips, short pelagic dives on swarming crustaceans at Closed Sea, for a same foraging effort. The diving behavior of the gentoo penguin therefore varies as a function of the locality and the site, closely related to prey availability. This study demonstrates the importance of foraging plasticity as a fundamental aspect of life history in coastal marine predators. KEY WORDS: Pygoscelis papua · Foraging strategy · Diving behavior · At-sea distribution · Behavioural plasticity · Geographic variation · Prey availability · Marine predator Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 302. Online publication date: November 04, 2005 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2005 Inter-Research.

Winter distribution and behaviour of gentoo penguins Pygoscelis papua at South Georgia

Knowledge of the spatial and temporal dynamics of foraging penguins is important to our understanding of the Southern Ocean marine ecosystem. We use satellite tracking to provide the first data on the distribution and behaviour of gentoo penguins (Pygoscelis papua) during the winter at South Georgia. Five penguins tracked from Bird Island remained close inshore, and although they did not return to the initial tagging site, they did appear to return to land each evening. They made diurnal trips to sea of similar distance from land as those during the breeding season, even though the constraints of chick rearing were absent. Despite potential greater flexibility in their responses to variations in prey availability in winter, the penguins still returned to land each night. This may reflect benefits from conserving energy by resting on land, possibly facilitating information exchange and avoiding predation. The distribution and behaviour of gentoo penguins during the winter enables efficient exploitation of a dynamic, patchy prey resource and may ultimately determine the timing of return to the colony, and onset of breeding in the following season.

Unusual Breeding by Seabirds at Marion Island During 1997/98

In 1997/98, breeding at subantarctic Marion Island was exceptionally good for five species of seabirds capable of foraging over wide areas and for a tern. The number of king penguin Aptenodytes patagonicus chicks surviving to the start of spring in 1997 was considerably more than previously recorded. Greater numbers of wandering Diomedea exulans and grey-headed Thalassarche chrysostoma albatrosses, northern giant petrels Macronectes halli and Kerguelen terns Sterna virgata bred than previously recorded, and more southern giant petrels M. giganteus did so than in any other year since 1994. For southern giant petrels, reproductive success was higher than in any other year, as was survival of chicks of northern giant petrels. Conversely, for two seabirds that feed close to the island, gentoo penguin Pygoscelis papua and Crozet shag Phalacrocorax [atriceps] melanogenis, 1997/98 was a particularly poor breeding season. Gentoo penguins initiated breeding later than usual and fledged few chicks. The number of Crozet shags that bred decreased; probably about 25% of the adult population did not breed. For two species with an intermediate foraging range that eat mainly crustaceans, macaroni Eudyptes chrysolophus and eastern rockhopper E. chrysocome filholi penguins, breeding was not noticeably different from normal except that chicks of rockhopper penguins fledged with a slightly heavier mass than in other years. However, for both these penguins, the mass of adults on arrival at colonies decreased substantially in the following (1998/99) breeding season. The unusual breeding by most of the seabirds coincided with the El Niño Southern Oscillation (ENSO) event of 1997/98. This synchrony contrasts with lagged responses to ENSO events of seabirds that breed farther south in the Southern Ocean. Continued monitoring of seabirds over well-separated sites in the Southern Ocean may elucidate how climatic perturbations operating at a global scale impact seabirds in the region.

Population, Breeding, Diet and Conservation of the Crozet Shag Phalacrocorax [atriceps] Melanogenis at Marion Island, 1994/95–2002/03

The number of Crozet shags or cormorants Phalacrocorax [atriceps] melanogenis breeding at subantarctic Marion Island decreased by 68% from 841 pairs in 1994/95 to 272 pairs in 2002/03. The mean number of pairs at colonies also decreased and was significantly related to the overall number of birds breeding in any given season. The decreases coincided with a period of warming and reduced precipitation at Marion Island and with a decrease in the number of gentoo penguins Pygoscelis papua breeding there. Both these seabird species forage inshore and there is considerable overlap in their diets. Nototheniid fish and the decapod Nauticaris marionis continued to be important in the diet of Crozet shags, but a change in dominance among nototheniid prey suggests availability of prey to shags changed after the mid 1980s. Crozet shags breed for the first time when aged three years. It is probable that about 25% of the mature population did not breed in 1997/98, coincident with a strong El Niño Southern Oscillation event. In four seasons, breeding pairs on average fledged 0.30 chicks from first clutches, an amount thought inadequate to sustain the population. Crozet shags at the Prince Edward Islands should now be regarded as Endangered. Placing breeding colonies in the most highly protected zone on Marion Island, considering the establishment of an ex situ population and undertaking a genetic study of the specific status of the Crozet shag are recommended conservation measures.

Population and Breeding of the Gentoo Penguin Pygoscelis Papua at Marion Island, 1994/95 – 2002/03

The numbers of gentoo penguins Pygoscelis papua breeding at subantarctic Marion Island fell by 40% from 1994/95 to 2002/03, from 1 352 pairs to 806 pairs. Apart from a slight increase in 1998/99, there was a steady decrease in numbers breeding between 1995/96 and 2000/01, when the population stabilized. There is indication that in some years not all breeders nested and that some birds relocated to another colony after disturbance. From first clutches, pairs on average fledged between 0.01 chicks in 1997/98 and 0.58 chicks in 2002/03 (mean 0.38 ± 0.21). In 1994/95, replacement clutches increased the overall production of fledged chicks by 11%. Based on demographic parameters measured at other localities, the production of chicks at Marion Island was inadequate to maintain the population during the period 1995/96 – 2000/01. Consistency in trends in breeding success at five colonies suggests that factors operating at a mesoscale, rather than those specific to particular colonies, often influenced breeding success. Laying was later than normal in 1997/98, when there was almost total breeding failure with large losses of eggs and small chicks to returning Subantarctic skuas Catharacta antarctica. Future research on this Near Threatened species at Marion Island must take full account of its susceptibility to human disturbance.

The mechanical properties of down feathers from gentoo penguins (Pygoscelis papua)

AbstractIn a recent paper, Dawson et al. (1999) investigated how the morphology of the contour and downy afterfeathers of gentoo penguins Pygoscelis papua function as thermal insulators. Their model considered how the morphology of individual feather barbs interact to create an efficient insulatory barrier. They noted that, during diving, the feathers must be compressed and return to their original configuration due to stored strain energy. In addition, the downy feathers of penguins have to withstand significant wind loading whilst the birds are on land (Taylor, 1986). Despite the obvious necessity for mechanical competence and resilience of down feathers, we still know little about their mechanical performance.

Inter-Annual Variation in the Autumn Diet of the Gentoo Penguin at Laurie Island, Antarctica

-The diet of adult Gentoo Penguin (Pygoscelis papua) was investigated during the autumns of 19931996 on Laurie Island, South Orkney Islands (60'46'S, 44?42'W), Antarctica. Fishes were the most important prey by mass in 1995 (81.1%) and 1996 (60.5%) while crustaceans predominated in 1993 (70% by mass). Among fishes, species of the family Nototheniidae predominated in the diet with G. gibberifrons the most important prey by mass in 1993 and 1995 and N. nybelini in 1996. Other nototheniid fish such as L. nudifrons and T newnesi were also well represented in the three sampling periods. Krill (Euphausia superba) was largely the most important prey among the eleven crustacean taxa identified in the samples. A total of 1,628 squid lower beaks was found, 97% identified as Psychroteuthis glacialis. Diet composition in terms of frequency of occurrence, mass and number is compared with previous studies. Received 17 November 1999, accepted 26January 2000.

Penguins of the Magellan region

SUMMARY: The Magellan region, including the Falkland Islands, is one of the world’s most important areas for seabirds, and especially penguins. World-wide there are 17 species of penguin; 7 of these regularly breed around the coastal waters of South America, and 5 within the Magellan region. These are the King Penguin (Aptenodytes patagonicus), Gentoo Penguin (Pygoscelis papua), Rockhopper Penguin (Eudyptes c. chrysocome), Macaroni Penguin (Eudyptes chrysolophus) and Magellanic Penguin (Spheniscus magellanicus). During the last five years, a review of the breeding populations of penguins within the Magellan region was conducted. This work included population censuses of all the surface breeding species throughout the Falkland Islands and southern South America. The results of this work are presented, along with other cited information, to provide a summary of the current knowledge of penguin populations within the Magellan region.

Influence of sampling protocol on diet determination of gentoo penguins Pygoscelis papua and Antarctic fur seals Arctocephalus gazella

The influence of two sampling protocols on diet determination of two marine predators, the gentoo penguin (Pygoscelis papua) and Antarctic fur seal (Arctocephalus gazella), was investigated. The collection of diet samples on three occasions over a 2-week period was compared with collecting all samples during a single session, as current CCAMLR Ecosystem Monitoring Programme protocols recommend. Some differences in the mass of food recovered from penguins were found but this was attributed to the mass of penguin sampled. There were no differences in diet composition between protocols and although body mass was a significant determinant of the mean length of krill Euphausia superba recovered from penguins, there were no differences between sampling protocols. This study has shown that differences between sampling frequencies are small and a variety of sampling protocols can produce results acceptable for inter-annual monitoring. The mass of sampled individuals can account for significant variation and should be recorded, especially if sampling frequencies and sizes are low.

The movements of gentoo penguins Pygoscelis papua from Ardley Island, Antarctica

The movements of gentoo penguins (Pygoscelis papua) in Antarctica were studied by equipping a total of 37 birds captured at Ardley Island, South Shetlands between December 1991 and May 1996 with position-determining devices. Information on area usage was derived from 20 of these devices and covered the incubation period (N = 3 birds), the chick-rearing period (N = 14 birds) and the over-wintering period (N = 3 birds). During incubation birds only ventured further than 50 km from the colony 20% of the time and no individual ranged further than 200 km from the colony. In contrast, no individuals attending chicks ranged further than 16 km from the colony. During winter the maximum distance ranged from the colony was 268 km. Mean distances between the birds and the colony were 80, 81 and 127 km. Individual birds tended to associate with one spot, making short (10 day) forays away before returning to nodal areas. The ranging capacity of gentoo penguins appears considerably less than that of sympatric congeners and may reflect the ability of gentoo penguins to dive deeper and thus exploit prey not accessible to congeners.

Foraging ecology of Gentoo Penguins Pygoscelis papua at Macquarie Island during the period of chick care

The diet, diving behaviour, swimming velocity and foraging range of Gentoo Penguins Pygoscelis papua were studied at Macquarie Island during the breeding season in the 1993–1994 austral summer. Gentoo Penguins are considered to be inshore feeders, and at Macquarie Island the diet and estimated foraging ranges supported this. The diet consisted of 91.6% fish and 8.3% squid, by mass. The dominant prey taxa were the fish Gymnoscopelus sp. and Paranotothenia magellanica. A mixture of pelagic and benthic prey was consumed, with a greater proportion of benthic species occurring later in the season. The penguins exhibited a strong diurnal pattern in their diving behaviour. Deep diving (≥30 m) began near sunrise (03.00 h) and finished close to sunset (21.00 h). Diving at night was less common and very shallow (<10 m). Early in the breeding season, dive profiles indicated that birds were probably following vertically migrating pelagic prey through the water column and were foraging in waters over 100 m deep. Later in the season, more uniform, shallower depths were used, suggesting an increase in benthic foraging activity. These changes in dive pattern and depth were consistent with the habitat preferences of prey species found in the diet. Gentoo Penguins swam at 1.04 m per s and had a maximum potential foraging range of about 26 km for single‐day trips. They tended to forage within 14 km of the colony, with a mean range of 5.4 km. This range encompassed the deep ocean habitat to the west and east of the island and a shallow area to the north.

The new Penguin enclosure at Edinburgh Zoo: the Palace for the 1990s

Penguins have been exhibited at Edinburgh Zoo since 1914 and the Zoo is well‐known for its expertise in keeping and breeding these birds, in particular the King penguin Aptenodvtes patagonica and Gentoo penguin Pygoscelis papua. Remodelling and extension of the existing penguin enclosure was completed in 1992 and a young group of Macaroni penguins Eudyptes chrysolophus has been added to the exhibit. The new enclosure is believed to be the largest penguin enclosure in existence and the larger and deeper pool has allowed the birds greater opportunity for swimming. The condition of King and Gentoo penguins has visibly improved and both species have produced young in the two breeding seasons since the reopening. In this paper the planning and design of the enclosure and water filtration is described, together with brief notes on the management of the birds.

Comparative fuel metabolism in Gentoo and King Penguins: adaptation to brief versus prolonged fasting

To compare fuel utilization in large birds adapted to brief or prolonged fasting, protein and lipid utilization were quantified in the Gentoo Penguin (Pygoscelis papua) and the King Penguin (Aptenodytes patagonica). The inshore feeder Gentoo Penguin fasts for only a few days in its colony, while King Penguin chicks starve for several months in the subantarctic winter and male King Penguins starve for 5–6 weeks at the beginning of their breeding cycle. After an initial decrease in both daily body mass loss and nitrogen excretion during the first days of food deprivation, these two parameters thereafter stabilized at low values. At that time, protein utilization accounted for 15% of total energy expenditure in Gentoo Penguins and only 6% in King Penguin chicks during winter, the remainder (85% and 94%, respectively) being provided by fat oxidation. Similar percentages in fuel metabolism as seen in chicks during winter were reached in fasting adult King Penguins and spring chicks. However, a seasonal adaptation occurs in fasting chicks because energy expenditure is lower during winter. As previously described in starved mammals, the effectiveness in protein sparing could be related to the initial adiposity of the birds: the larger the fat stores (about 9% and 30% in Gentoo Penguins and winter chicks of King Penguins, respectively), the longer the fast duration and the better the level of protein conservation.