Comparing King,Gentoo, and Royal Penguin Responses to Pedestrian Visitation

ABSTRACT For wildlife managers, determining inter-species differences in the behavioral responses of seabirds to visitation can allow greater efficacy of visitor guidelines. Two key management outcomes for such information include 1) tailoring visitor guidelines to protect the most sensitive species and 2) improving self-regulation during visits by identifying behaviors likely to indicate a change in the natural activity of visited species. On subantarctic Macquarie Island, Australia, I collected the behavioral responses of guarding king (Aptenodytes patagonicus), gentoo (Pygoscelis papua), and royal (Eudyptes schlegeli) penguins before, during, and after exposure to a standardized pedestrian visit, to compare species' behavioral responses to visitation. Gentoo penguins appeared more sensitive than royal or king penguins, exhibiting altered behavior for 5 minutes after the stimulus was removed; this pattern was not evident in kings or royals. Response behaviors useful for visitors to assess their impact on penguins include vigilance (repeated rapid head turning) in all 3 species, agonism in king and royal penguins (reaching and striking at conspecifics), and low threat-display (bill pointing) in gentoo penguins. This study is valuable for wildlife managers as it provides practical information in the application of on-ground visitor guidelines.     

UV-reflecting and absorbing body regions in gentoo and king penguin: Can they really be used by the penguins as signals for conspecific recognition?

Photographs of gentoo and king penguins were taken in the field on a bright and sunny day first in colour (here reproduced in black and white) and then, seconds later, through a filter that transmits only UV radiation and blocks all visible light. Because of the lower light intensity and different focal point of UV, it is unavoidable that the UV photographs turn out less sharp and less well focused than photographs taken with visible light. Comparisons of the two sets of photographs show that king penguins with white (but not yellow or orange) auricular patches reflect UV from these areas. Furthermore, the beaks of juvenile gentoo penguins, but not those of the adults, are UV reflectant. The findings are discussed in view of recent suggestions that UV reflection in penguins could be part of a communication system. However, this paper argues that as long as UV perception in penguins has not been demonstrated, UV reflection in penguins ought to be seen as an “associative phenomenon” with no significance to penguin behaviour.     

Liver and plasma retinol (vitamin A) in wild, and liver retinol in captive penguins (Spheniscidae)

In rockhopper penguins ( Eudyptes crestatus ), liver concentrations of retinol (vitamin A) were significantly higher in post-moult than in pre-moult birds. In Magellanic penguins ( Spheniscus magelianicus ), plasma concentrations of retinol were significantly higher in post-moult than in pre-moult birds; liver retinol concentrations were also higher, but not significantly so.
The pre- and post-moult Magellanics had higher liver and lower plasma retinol concentrations than the pre- and post-moult rockhoppers.
Captive blackfooted (jackass) ( Spheniscus demersus ), king ( Aptenodytes patagonica ) and Humboldt ( Spheniscus humboldti ) penguins had liver vitamin A stores significantly lower than those of the free-living rockhopper, Magellanic, gentoo ( Pygoscelis papua ), emperor ( Aptenodytes forsteri ), chinstraps ( Pygoscelis antarctica ) and Adélie ( Pygoscelis adeliae ) penguins.     

Energetic costs of surface swimming and diving of birds

The energetic costs of swimming at the surface (swimming) and swimming underwater (diving) are compared in tufted ducks (Aythya fuligula) and three species of penguins, the gentoo (Pygoscelis papua), the king (Aptenodytes patagonicus), and the emperor (Aythya forsteri). Ducks swim on the surface and use their webbed feet as paddles, whereas penguins tend to swim just below the surface and use their flippers as hydrofoils, the latter being much more efficient. Penguins are more streamlined in shape. Thus, the amount of energy required to transport a given mass of bird a given distance (known as the cost of transport) is some two to three times greater in ducks than in penguins. Ducks are also very buoyant, and overcoming the force of buoyancy accounts for 60% and 85% of the cost of descent and remaining on the bottom, respectively, in these birds. The energy cost of a tufted duck diving to about 1.7 m is similar to that when it is swimming at its maximum sustainable speed at the surface (i.e., approximately 3.5 times the value when resting on water). Nonetheless, because of the relatively short duration of its dives, the tufted duck dives well within its calculated aerobic dive limit (cADL, usable O(2) stores per rate of O(2) usage when underwater). However, these three species of penguins have maximum dive durations ranging from 5 min to almost 16 min and maximum dive depths from 155 to 530 m. When these birds dive, they have to metabolise at no more than when resting in water in order for cADL to encompass the duration of most of their natural dives. In gentoo and king penguins, there is a fall in abdominal temperature during bouts of diving; this may reduce the oxygen requirements in the abdominal region, thus enabling dive duration to be extended further than would otherwise be the case.     

Sex Identification of Four Penguin Species Using Locus‐Specific PCR

Traditional methods for sex identification are not applicable to sexually monomorphic species, leading to difficulties in the management of their breeding programs. To identify sex in sexually monomorphic birds, molecular methods have been established. Two established primer pairs (2550F/2718R and p8/p2) amplify the CHD1 gene region from both the Z and W chromosomes. Here, we evaluated the use of these primers for sex identification in four sexually monomorphic penguin species: king penguins (Aptenodytes patagonicus), rockhopper penguins (Eudyptes chrysocome), gentoo penguins (Pygoscelis papua), and Magellanic penguins (Spheniscus magellanicus). For all species except rockhopper penguins, primer pair 2550F/2718R resulted in two distinct CHD1Z and CHD1W PCR bands, allowing for sex identification. For rockhopper penguins, only primer pair p8/p2 yielded different CHD1Z and CHD1W bands, which were faint and similar in size making them difficult to distinguish. As a result, we designed a new primer pair (PL/PR) that efficiently determined the gender of individuals from all four penguin species. Sequencing of the PCR products confirmed that they were from the CHD1 gene region. Primer pair PL/PR can be evaluated for use in sexing other penguin species, which will be crucial for the management of new penguin breeding programs. Zoo Biol 32:257–261, 2013. © 2012 Wiley Periodicals, Inc.     

Killer whale predation on penguins in Antarctica

We report here the first published observations of killer whales (Orcinus orca) feeding on penguins in Antarctica. The sightings took place in the Gerlache Strait off the western Antarctic Peninsula during February 2010. Two species of pygoscelid penguins were taken—gentoo (Pygoscelis papua, at least four individuals) and chinstrap (P. antarctica, 2). From remains left at the surface, it was clear that the killer whales fed mainly on the breast muscles, although some penguins may have been swallowed whole. The killer whales were ecotype B, which are purported seal specialists, but we also saw ecotype A, prey specialists on Antarctic minke whales Balaenoptera bonaerensis, chase, but not catch penguins. Because of their small relative size, if penguins are regularly targeted by killer whales in Antarctica, the impact on their populations could be significant.     

Isotopic discrimination between food and blood and feathers of captive penguins: implications for dietary studies in the wild

Using measurements of naturally occurring stable isotopes to reconstruct diets or source of feeding requires quantifying isotopic discrimination factors or the relationships between isotope ratios in food and in consumer tissues. Diet-tissue discrimination factors of carbon ((13)C/(12)C, or delta (13)C) and nitrogen ((15)N/(14)N, or delta (15)N) isotopes in whole blood and feathers, representing noninvasive sampling techniques, were examined using three species of captive penguins (king Aptenodytes patagonicus, gentoo Pygoscelis papua, and rockhopper Eudyptes chrysocome penguins) fed known diets. King and rockhopper penguins raised on a constant diet of herring and capelin, respectively, had tissues enriched in (15)N compared to fish, with discrimination factors being higher in feathers than in blood. These data, together with previous works, allowed us to calculate average discrimination factors for (15)N between whole lipid-free prey and blood and feathers of piscivorous birds; they amount to +2.7 per thousand and +4.2 per thousand, respectively. Both fish species were segregated by their delta (13)C and delta (15)N values, and importantly, lipid-free fish muscle tissue was consistently depleted in (13)C and enriched in (15)N compared to whole lipid-free fish. This finding has important implications because previous studies usually base dietary reconstructions on muscle of prey rather than on whole prey items consumed by the predator. We tested the effect of these differences using mass balance calculations to the quantification of food sources of gentoo penguins that had a mixed diet. Modeling indicated correct estimates when using the isotopic signature of whole fish (muscle) and the discrimination factors between whole fish (muscle) and penguin blood. Conversely, the use of isotopic signatures of muscle together with discrimination factors between whole fish and blood (or the reverse) leads to spurious estimates in food proportions. Consequently, great care must be taken in the choice of isotopic discrimination factors to apply to wild species for which no controlled experiments on captive individuals have been done. Finally, our results also indicate that there is no need to remove lipids before isotopic analysis of avian blood.     

The influence of historical climate changes on Southern Ocean marine predator populations: a comparative analysis

The Southern Ocean ecosystem is undergoing rapid physical and biological changes that are likely to have profound implications for higher‐order predators. Here, we compare the long‐term, historical responses of Southern Ocean predators to climate change. We examine palaeoecological evidence for changes in the abundance and distribution of seabirds and marine mammals, and place these into context with palaeoclimate records in order to identify key environmental drivers associated with population changes. Our synthesis revealed two key factors underlying Southern Ocean predator population changes; (i) the availability of ice‐free ground for breeding and (ii) access to productive foraging grounds. The processes of glaciation and sea ice fluctuation were key; the distributions and abundances of elephant seals, snow petrels, gentoo, chinstrap and Adélie penguins all responded strongly to the emergence of new breeding habitat coincident with deglaciation and reductions in sea ice. Access to productive foraging grounds was another limiting factor, with snow petrels, king and emperor penguins all affected by reduced prey availability in the past. Several species were isolated in glacial refugia and there is evidence that refuge populations were supported by polynyas. While the underlying drivers of population change were similar across most Southern Ocean predators, the individual responses of species to environmental change varied because of species specific factors such as dispersal ability and environmental sensitivity. Such interspecific differences are likely to affect the future climate change responses of Southern Ocean marine predators and should be considered in conservation plans. Comparative palaeoecological studies are a valuable source of long‐term data on species’ responses to environmental change that can provide important insights into future climate change responses. This synthesis highlights the importance of protecting productive foraging grounds proximate to breeding locations, as well as the potential role of polynyas as future Southern Ocean refugia.     

Winter distribution and behaviour of gentoo penguins<Emphasis Type="Italic"> Pygoscelis papua</Emphasis> 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.     

Krill-feeding behaviour of gentoo penguins as shown by animal-borne camera loggers

Animal-borne camera loggers were used to examine the patterns of prey encounter and feeding behaviour of gentoo penguins at King George Island, Antarctica. The still images from the camera loggers showed that the penguins encountered the swarms of krill for 25.5% (range: 8–38%) of their dives (>5 m) on average, during their foraging trips (mean duration of 5.4 h, n = 7 trips). They encountered krill swarms during the dives to 10–70 m depth, in pelagic as well as benthic habitats. In the benthic habitat, the penguins swam just above the sea floor and headed downward over a krill swarm, probably using the sea floor to assist them to feed on mobile swarms. The shallow coastal waters would be the important foraging habitat of gentoo penguins breeding in King George Island.     

Blood glucose partition and levels of glycolytic enzymes in erythrocytes and somatic tissues of penguins

1. A comparative study was carried out on blood glucose partition and glucose metabolism of penguin erythrocytes and somatic tissues. Pygoscelidae penguins (Pygoscelis antarctica and P. papua) were used in these experiments. 2. Blood glucose partition was established by assaying whole blood and plasma glucose in several individuals of the gentoo and chinstrap penguins. 3. It was found that almost all the whole blood sugar is compartmentalized at the plasma site, the red blood cells being ineffective in regard to glucose metabolism. 4. Levels of hexokinase, phosphoglucose isomerase, phosphofructokinase, fructose bisphosphate aldolase, glyceraldehyde phosphate dehydrogenase, phosphoglycerate kinase, phosphopyruvate hydratase (enolase), pyruvate kinase, alpha-glycerolphosphate dehydrogenase and fructose bisphosphate phosphatase were estimated in the erythrocytes of both gentoo and chinstrap penguins, the same determinations being carried out also on the somatic tissues (leg muscle, breast muscle, heart muscle, liver and brain) of the gentoo.     

Detection, differentiation, and abundance estimation of penguin species by high-resolution satellite imagery

Due to its high spatial resolution, broad spatial coverage, and cost-effectiveness, commercial satellite imagery is rapidly becoming a key component of biological monitoring in the Antarctic. While considerable success in surveying emperor penguins (Aptenodytes forsteri) has been facilitated by their large size and the visual simplicity of their habitat, there has been considerably less progress in mapping colonies on the Antarctic Peninsula and associated sub-Antarctic islands where smaller penguin species breed on topographically complex terrain composed of mixed substrates. Here, we demonstrate that Adélie penguin (Pygoscelis adeliae), chinstrap penguin (P. antarcticus), gentoo penguin (P. papua), and macaroni penguin (Eudyptes chrysolophus) colonies can be detected by high-resolution (2-m multispectral, 40–50-cm panchromatic) satellite imagery and that under ideal conditions, such imagery is capable of distinguishing among groups of species where they breed contiguously. To demonstrate the potential for satellite imagery to estimate penguin population abundance, we use satellite imagery of Paulet Island (63°35′S, 55°47′W) to estimate a site-wide population of 115,673 (99,222–127,203) breeding pairs of Adélie penguins.     

Penguin responses to climate change in the Southern Ocean

Penguins are adapted to live in extreme environments, but they can be highly sensitive to climate change, which disrupts penguin life history strategies when it alters the weather, oceanography and critical habitats. For example, in the southwest Atlantic, the distributional range of the ice‐obligate emperor and Adélie penguins has shifted poleward and contracted, while the ice‐intolerant gentoo and chinstrap penguins have expanded their range southward. In the Southern Ocean, the El Niño‐Southern Oscillation and the Southern Annular Mode are the main modes of climate variability that drive changes in the marine ecosystem, ultimately affecting penguins. The interaction between these modes is complex and changes over time, so that penguin responses to climate change are expected to vary accordingly, complicating our understanding of their future population processes. Penguins have long life spans, which slow microevolution, and which is unlikely to increase their tolerance to rapid warming. Therefore, in order that penguins may continue to exploit their transformed ecological niche and maintain their current distributional ranges, they must possess adequate phenotypic plasticity. However, past species‐specific adaptations also constrain potential changes in phenology, and are unlikely to be adaptive for altered climatic conditions. Thus, the paleoecological record suggests that penguins are more likely to respond by dispersal rather than adaptation. Ecosystem changes are potentially most important at the borders of current geographic distributions, where penguins operate at the limits of their tolerance; species with low adaptability, particularly the ice‐obligates, may therefore be more affected by their need to disperse in response to climate and may struggle to colonize new habitats. While future sea‐ice contraction around Antarctica is likely to continue affecting the ice‐obligate penguins, understanding the responses of the ice‐intolerant penguins also depends on changes in climate mode periodicities and interactions, which to date remain difficult to reproduce in general circulation models.     

Breeding ecology of the gentoo penguin <Emphasis Type="Italic">Pygoscelis papua</Emphasis> at Kerguelen Archipelago

The gentoo penguin (Pygoscelis papua) is one of the most widespread penguin species and has been proven to be highly plastic in many aspects of its ecology. However, data from their sub-Antarctic range suggest an unexplained decline of their populations over the last 10–20 years, stressing the need for additional knowledge on their breeding ecology and demography. The present study provides insights into the breeding ecology of the gentoo penguin at a major breeding site, Kerguelen Archipelago, over three breeding seasons (1987, 2002 and 2003). Similarly to other northern populations, gentoo penguins breeding at Kerguelen exhibited winter laying, slow provisioning rate, slow growth rate associated with an extended rearing period and relatively low breeding success compared to southern populations. Our study also revealed interannual differences in the timing of laying and growth parameters as well as unusual sex differences in parental investment. Despite their high plasticity, there are indications that gentoo penguins at the northern edge of their range might work at the upper limit of their capacities. Sub-Antarctic populations would, therefore, be more sensitive to environmental changes than more southerly ones and need to be closely monitored.     

Morphometric and genetic evidence for four species of gentoo penguin

Gentoo penguins (Pygoscelis papua) are found across the Southern Ocean with a circumpolar distribution and notable genetic and morphological variation across their geographic range. Whether this geographic variation represents species‐level diversity has yet to be investigated in an integrative taxonomic framework. Here, we show that four distinct populations of gentoo penguins (Iles Kerguelen, Falkland Islands, South Georgia, and South Shetlands/Western Antarctic Peninsula) are genetically and morphologically distinct from one another. We present here a revised taxonomic treatment including formal nomenclatural changes. We suggest the designation of four species of gentoo penguin: P. papua in the Falkland Islands, P. ellsworthi in the South Shetland Islands/Western Antarctic Peninsula, P. taeniata in Iles Kerguelen, and a new gentoo species P. poncetii, described herein, in South Georgia. These findings of cryptic diversity add to many other such findings across the avian tree of life in recent years. Our results further highlight the importance of reassessing species boundaries as methodological advances are made, particularly for taxa of conservation concern. We recommend reassessment by the IUCN of each species, particularly P. taeniata and P. poncetii, which both show evidence of decline.     

Daily activity and minimum food requirements during winter for gentoo penguins (Pygoscelis papua) in the South Shetland Islands, Antarctica

Estimates of daily activity and consequent demand for food during winter are scarce for many polar seabirds, yet essential for assessing constraints on foraging effort, demand for food, and potential competition with local fisheries. We affixed archival temperature tags to gentoo penguins (Pygoscelis papua) from two colonies in the South Shetland Islands to measure the frequency, timing, and duration of foraging trips and to estimate minimum food requirements during winter. Foraging trip frequencies ranged from 0.85 to 1.0 trips day⁻¹ and were positively correlated with day length. Early winter foraging trips more closely matched day length than late winter foraging trips. The data suggest that individuals maximize foraging time during the early winter period, likely to recover body mass following the breeding season and molt. The more attenuated response of foraging trip durations to increasing day length in late winter may be related to differences in local resource availability or individual behaviors prior to the upcoming breeding season. Minimum food requirements also exhibited a seasonal cycle with a mid-winter minimum. On average, minimum food requirements were estimated at 0.70 ± 0.12 kg day⁻¹. Extrapolated to the regional population of gentoo penguins, winter food requirements by gentoo penguins were equivalent to roughly 33% of annual krill catches by commercial fisheries in the South Shetland Island region over the past decade. Current expansion of the gentoo population and the krill fishery in the southern Scotia Sea warrants continued monitoring of gentoo penguins during winter.     

Alloparental feeding in Adélie penguins: why is it uncommon?

We investigated alloparental interactions and conditions which could facilitate or prevent the expression of alloparental behaviours in Adélie penguins (Pygoscelis adeliae), a long-lived seabird which nests in high-density colonies around Antarctica. Observation sessions were carried out during the crèche stage on 48 identified pairs and 50 identified chicks in a 217-nest subcolony. As the season progressed, young were fed less often by their own parents because these were increasingly absent from the breeding site and less responsive to their offspring’s solicitations. As a consequence, young and particularly those with a low body mass, coming from a two-chick brood, opted for gradually soliciting more from other adults to obtain food, preferentially those nesting in their direct vicinity. Unsuccessful breeders represented a low and constant part of the adult population and were not specifically solicited by unrelated young. Despite the increasing chick demand, only 4.1% (3 out of 73) of alloparental solicitations resulted in feeding, which is negligible compared to parental feeding. To investigate factors that could trigger the appearance of alloparental care, we carried out comparisons with king (Aptenodytes patagonicus) and emperor penguins (Aptenodytes forsteri) which represent the closest species for which data on alloparental behaviour were available. Our results show different trends to those observed in these species and three factors may explain the low occurrence of alloparental behaviour in Adélie penguins: (1) the low and constant proportion of unsuccessful breeders, (2) the absence of chick selectivity towards unsuccessful breeders, and (3) the late period of chick accessibility for potential alloparents.     

Why Huddle? Ecological Drivers of Chick Aggregations in Gentoo Penguins,Pygoscelis papua,across Latitudes

Aggregations of young animals are common in a range of endothermic and ectothermic species, yet the adaptive behavior may depend on social circumstance and local conditions. In penguins, many species form aggregations (aka. crèches) for a variety of purposes, whilst others have never been observed exhibiting this behavior. Those that do form aggregations do so for three known benefits: 1) reduced thermoregulatory requirements, 2) avoidance of unrelated-adult aggression, and 3) lower predation risk. In gentoo penguins, Pygoscelis papua, chick aggregations are known to form during the post-guard period, yet the cause of these aggregations is poorly understood. Here, for the first time, we study aggregation behavior in gentoo penguins, examining four study sites along a latitudinal gradient using time-lapse cameras to examine the adaptive benefit of aggregations to chicks. Our results support the idea that aggregations of gentoo chicks decrease an individual’s energetic expenditure when wet, cold conditions are present. However, we found significant differences in aggregation behavior between the lowest latitude site, Maiviken, South Georgia, and two of the higher latitude sites on the Antarctic Peninsula, suggesting this behavior may be colony specific. We provide strong evidence that more chicks aggregate and a larger number of aggregations occur on South Georgia, while the opposite occurs at Petermann Island in Antarctica. Future studies should evaluate multiple seabird colonies within one species before generalizing behaviors based on one location, and past studies may need to be re-evaluated to determine whether chick aggregation and other behaviors are in fact exhibited species-wide.     

Penguins from space: faecal stains reveal the location of emperor penguin colonies

Aim  To map and assess the breeding distribution of emperor penguins ( Aptenodytes forsteri ) using remote sensing.
Location  Pan-Antarctic.
Methods  Using Landsat ETM satellite images downloaded from the Landsat Image Mosaic of Antarctica (LIMA), we detect faecal staining of ice by emperor penguins associated with their colony locations. Emperor penguins breed on sea ice, and their colonies exist in situ between May and December each year. Faecal staining at these colony locations shows on Landsat imagery as brown patches, the only staining of this colour on sea ice. This staining can therefore be used as an analogue for colony locations. The whole continental coastline has been analysed, and each possible signal has been identified visually and checked by spectral analysis. In areas where LIMA data are unsuitable, freely available Landsat imagery has been supplemented.
Results  We have identified colony locations of emperor penguins at a total of 38 sites. Of these, 10 are new locations, and six previously known colony locations have been repositioned (by over 10 km) due to poor geographical information in old records. Six colony locations, all from old or unconfirmed records, were not found or have disappeared.
Main conclusions  We present a new pan-Antarctic species distribution of emperor penguins mapped from space. In one synoptic survey we locate extant emperor penguin colonies, a species previously poorly mapped due to its unique breeding habits, and provide a vital geographical resource for future studies of an iconic species believed to be vulnerable to future climate change.     

How do weather conditions affect the huddling behaviour of emperor penguins?

Huddling allows emperor penguins to conserve energy and survive their long winter fast while facing harsh climatic conditions. Here we report the first investigation into the effects of changes in wind speed and ambient temperature on different components of penguin huddling behaviour. We attached light and temperature recorders to male emperor penguins at the Pointe Géologie colony, Antarctica, which recorded huddling events. We then compared the frequency, duration, occurrence and intensity of huddling bouts, with ambient air temperatures and wind speeds. Huddling occurrence increased with lower ambient temperatures and higher wind speeds, whereas huddling intensity was mainly enhanced by lower ambient temperatures. Moreover, huddling group movements were linked to wind direction and its global density to lower ambient temperatures. Hence, emperor penguins complex huddling behaviour was modulated differently depending on these two parameters. Weather conditions may then affect emperor penguins ability to save energy and survive their winter fast.