Penguin Colonies Research Articles

Status of the Humboldt Penguin in Peru, 1999-2000

The status of the Humboldt Penguin (Spheniscus humboldti) was investigated in Peru after the 1997-98 El Niño event, the strongest of the last century. Penguin numbers along the southern and central coast of Peru (97% of the total) did not differ significantly between 1999 and 2000; the average number was 4,425 individuals. In 1999, the proportion of juveniles (one-year-old birds) was only 0.2% compared with 7% in 2000, probably as a result of the 1997-98 El Niño. Penguins were found from La Foca Island (512’S) to Punta Coles (1742’S). However, the majority (78%) were clustered in five localities, Punta San Juan (36%), San Juanito Islet (11%), Hornillos Island (10%), Pachacamac Island (12%) and Tres Puertas (9%). The size and distribution of penguin colonies have changed over the last 15 years. Penguins have abandoned sites at Punta Corio, Sombrerillo and Morro Sama, and have decreased significantly in numbers in Punta San Fernando and Punta La Chira, where human disturbance has increased, mainly due to local fisheries activities. Penguins have increased at Punta San Juan, San Juanito Islet and San Gallan Island, all of which are partially protected. Half of the penguins were located in guano bird reserves, primarily at Punta San Juan. Guano bird reserves provide some protection against terrestrial predators and human disturbance; however, periodical guano extraction decreases their breeding success. Most penguin sites were found in inaccessible and marginal areas, which were vulnerable to occasional and unpredictable flooding from ocean swells. The methodology recommended by the Population and Habitat Viability Assessment workshop for a consistent census of penguins in Peru and Chile during the molting period was validated at the Punta San Juan Reserve. Continued monitoring of Humboldt Penguin numbers is recommended in order to more fully understand patterns of fluctuation and to be able to detect changes of conservation concern as early as possible. Collaborative efforts between local authorities and conservation biologists are needed to monitor and protect this vulnerable species.

Late-Holocene initiation of ice-free ecosystems in the southern Ross Sea, Antarctica

New data on marine sediments, seawater paleotemperatures, and the occupation his- tory of Adelie penguins indicate that modern ice-free conditions in the southern Ross Sea developed only within the last 1000 yr. Here we show that penguins permanently abandoned the southern Vic- toria Land Coast 2000 yr ago when extensive sea-ice cover blocked access to ice-free terrain for breeding. The first colonization of Ross Island in East McMurdo Sound, where over 300 000 penguins breed today, did not commence until after 1170 yr BP when coastal areas became exposed from under the Ross Ice Shelf. Our results demonstrate that investigations of abandoned penguin colonies can provide increased resolution to Holocene paleoclimatic records and paleoceanographic conditions in Antarctica.

A potential source of atmospheric sulfur from penguin colony emissions

Samples of fresh penguin excrements and lake sediments composed of aged penguin excrements were collected on an Antarctic Peninsula island. Gases emitted from these samples were collected and analyzed for volatile organosulfur compounds. No dimethyl sulfide (DMS) was found. However, dimethyl trisulfide (DMTS), dimethyl tetrasulfide (DMTTS), and dimethyl pentasulfide (DMPS) were found among the numerous organic compounds emitted from fresh penguin droppings. These sulfur compounds account for as mush as 13.5% of the emitted gases, but they have not been reported previously in atmospheric gases and therefore may represent a hitherto undetected source of atmospheric sulfur. To evaluate the potential contribution of this non‐DMS biogenic source to the atmospheric sulfur reservoir at high southern latitudes, measurements of various chemical species in aerosols at several coastal Antarctic locations were analyzed and compared. The locations include Zhongshan Station (China) and Dumont D'Urville (France) in east Antarctica. Tentative calculations based on assumptions of similar aerosol sources and composition at these locations show that in areas downwind from large penguin colonies up to 5.5 × 10−5 nmol m−3 sulfur may be attributed to penguin emissions on a per‐penguin basis. Depending on the size of penguin population at a given location, sulfur from this non‐DMS source may account for 5–15% of the total non‐sea‐salt (nss) sulfur in these areas. Such high contributions may significantly impact the atmospheric sulfur burden and alter the sulfur budget in the high southern latitudes.

Microalgal communities from ornithogenic soils at Cierva Point, Antarctic Peninsula

Microalgal communities inhabiting three soil sites with different degrees of influence from penguin colonies within and near the Cierva Point Site of Special Scientific Interest (64°10′S, 61°01′W) were analysed and their species composition and diversity compared with those in nearby mineral soils. Concentrations of NH4-N and PO4-P increased drastically as a function of the degree of use by the penguins. This chemical variation was accompanied by changes in algal community structure: chlorophytes and diatoms dominated the less enriched site, while cyanobacteria were the exclusive dominants at the most enriched site. A significant fraction (28%) of the recorded species were also present in the mineral soils, but their abundances decreased with nutrient concentration. Biodiversity as measured by the Shannon diversity index was lower than in the mineral soils, and dropped from 1.79 to 0.44 with increasing influence of the bird colonies. These observations indicate that soil algal biodiversity decreases with increasing trophic status, as recorded for freshwater phytoplanktonic communities.

Adélie penguin diet and climate change during the middle to late Holocene in northern Marguerite Bay, Antarctic Peninsula

We investigated one active and three abandoned Adelie penguin (Pygoscelis adeliae) colonies in northern Marguerite Bay, Antarctic Peninsula, during austral summer 2000. Extinct colonies were located by ground survey on small islands and recognized by concentrations of nest pebbles. The colonies were excavated to recover organic remains from ornithogenic soils. Radiocarbon dates on penguin bone and eggshell provided a 6,000-year occupation history after correction for the marine-carbon reservoir effect; this history was compared to the paleoclimate record (ice cores and marine sediments) to assess patterns in occupation by penguins with episodes of climate change. We quantified prey remains recovered from the sites to examine potential dietary shifts by penguins with climatic change. Two species, Antarctic silverfish (Pleuragramma antarcticum) and squid (Psychroteuthis glacialis), were most commonly represented in the sediments. The data indicate that silverfish may have been exploited more during cool, and squid in warm climatic intervals in the past.

HABITAT USE AND BREEDING DISTRIBUTION OF MAGELLANIC PENGUINS IN NORTHERN SAN JORGE GULF, PATAGONIA, ARGENTINA

Abstract We evaluated distribution and size of Magellanic Penguin (Spheniscus magellanicus) colonies in northern San Jorge Gulf, Argentina, characterizing nesting habitat at 14 islands with colonies (IC) and 28 islands without nesting penguins (INC). Digital analysis of a Landsat TM satellite image and field measurements were used to assess vegetation and substrate. The 14 breeding colonies ranged in size from 13 to 96,300 nests, and number of breeding pairs was estimated at 218,460. Colonies were only located on islands. Digital analysis of the satellite image showed that the proportion of area with shrub–steppe vegetation was significantly higher at IC than at INC (38.6 vs. 4.9%), whereas percentage of rocky substrate was lower at IC (33.6 vs. 64.8%). Percentage of vegetation cover was positively correlated with island area and with number of breeding pairs. Most nests (98.6%) were located under bushes, whereas the rest were burrows dug into the substrate. Mean size of bushes used for nesting was higher...

Habitat use and Breeding Distribution of Magellanic Penguins in Northern San Jorge Gulf, Patagonia, Argentina

Abstract We evaluated distribution and size of Magellanic Penguin (Spheniscus magellanicus) colonies in northern San Jorge Gulf, Argentina, characterizing nesting habitat at 14 islands with colonies (IC) and 28 islands without nesting penguins (INC). Digital analysis of a Landsat TM satellite image and field measurements were used to assess vegetation and substrate. The 14 breeding colonies ranged in size from 13 to 96,300 nests, and number of breeding pairs was estimated at 218,460. Colonies were only located on islands. Digital analysis of the satellite image showed that the proportion of area with shrub–steppe vegetation was significantly higher at IC than at INC (38.6 vs. 4.9%), whereas percentage of rocky substrate was lower at IC (33.6 vs. 64.8%). Percentage of vegetation cover was positively correlated with island area and with number of breeding pairs. Most nests (98.6%) were located under bushes, whereas the rest were burrows dug into the substrate. Mean size of bushes used for nesting was higher at IC (4.47 vs. 0.99 m2) as was the percentage of silt–clay substrate (47.31 vs. 1.98%). Coast minimum slopes at INC were steeper than the slopes of entrance routes at IC (27.6 vs. 5.7°). Probability of occupation of islands increased with amount of shrub-type vegetation cover and silt–clay substrate, and decreased with increasing slopes and amount of sandy substrate. Magellanic Penguins selected islands with shrub-type vegetation and soil that allow building nests with adequate cover. These results are consistent with other studies showing vegetation cover is an important nesting requirement for Magellanic Penguins.

Radiocarbon dates from abandoned penguin colonies in the Antarctic Peninsula region

Sixty-three radiocarbon dates on organic remains from 21 abandoned colonies of chinstrap (Pygoscelis antarctica) and Adélie (P. adeliae) penguins on 12 islands in the Antarctic Peninsula region are evaluated for determining the occupation history of penguins in this region. This record also provides a means for assessing sea-level change, glacial advances and retreats, and population responses by penguins to these events. All conventional dates were corrected for the marine-carbon reservoir effect by applying a ΔR = 700±50 BP and marine calibration curves. The 63 calibrated dates give 2σ ranges (95% confidence intervals) from modern to 5990 yr BP. These dates indicate progressively older occupations from north to south along the Antarctic Peninsula. No sites older than approximately 540 BP occur in the northern peninsula, either because they have not yet been found or older sites have been destroyed by solifluction and glacial scouring. Three dates from one locality near Rothera Point, Adelaide Island, also were calibrated with a ΔR = 750 ± 50 and 800 ± 50 BP. No difference was found between calibrated dates using these two other ΔR values, indicating that local corrections for variation in upwelling intensity may not be necessary.

A SPATIALLY EXPLICIT MODEL OF THE ANTARCTIC KRILL FISHERY OFF THE SOUTH SHETLAND ISLANDS

We show the development of a spatially explicit ecosystem model for the Euphausia superba fishery in the South Shetland Islands area (Antarctic Peninsula). We generated a virtual ecosystem, using a spatial automaton–geographic information system technique, to study management scenarios. We used literature data to generate the advection field, the initial krill biomass, and the distribution and size of penguin colonies in the area. Parameters for the fishing fleet were extracted from analysis of Chilean krill-fishing vessels. The model assumes that krill are passive current drifters and that penguin foraging occurs in areas close to their colonies. We analyzed the effect that a simulated 20-vessel fishing fleet would have on the availability of prey, considering the krill flux due to advection. The results show that it would be reasonable to manage the krill fishery in the South Shetland Islands as an interconnected set of ecotrophic modules, allocating the fleet downstream from the main penguin foraging sector.

Gene flow on the ice: genetic differentiation among Adélie penguin colonies around Antarctica.

Each summer Adélie penguins breed in large disjunct colonies on ice-free areas around the Antarctic continent. Comprising > 10 million birds, this species represents a dominant feature of the Antarctic ecosystem. The patchy distribution within a large geographical range, natal philopatry and a probable history of refugia, suggest that this species is likely to exhibit significant genetic differentiation within and among colonies. We present data from seven microsatellite DNA loci for 442 individuals from 13 locations around the Antarctic continent. With the exception of one locus, there was no significant genic or genotypic heterogeneity across populations. Pairwise FST values were low with no value > 0.02. When all colonies were compared in a single analysis, the overall FST value was 0.0007. Moreover, assignment tests were relatively ineffective at correctly placing individuals into their respective collection sites. These data reveal a lack of genetic differentiation between Adélie penguin colonies around the Antarctic continent, despite substantial levels of genetic variation. We consider this homogeneity in terms of the dispersal of individuals among colonies and the size of breeding groups and discuss our results in terms of the glacial history of Antarctica.

Life cycle of the tick Ixodesuriae in penguin colonies: relationships with host breeding activity

A survey of the temporal pattern of population structure and feeding activity of the seabird tick Ixodes uriae was conducted for the first time in two host species colonies: King penguin ( Aptenodytes patagonicus halli) and Macaroni penguin ( Eudyptes chrysolophus chrysolophus). The life cycle of the tick was investigated over 3 years in a King penguin colony and 2 years in a Macaroni penguin colony at Possession Island (Crozet Archipelago). There was a marked seasonal feeding activity pattern of ticks in both host species, connected with the presence of birds during the breeding season. Although the King penguin colonies were occupied throughout the year by birds, the favourable period for engorgement was limited to 3.5–4.5 months, and almost all the ticks overwintered in the unengorged state. Consequently, I. uriae probably completed its life cycle over 3 years in King penguin colonies. In contrast, this life cycle could be shortened to 2 years in Macaroni penguin colonies, as a result of a different timetable of the presence of birds for breeding and moulting. The relationships between such plasticity and the host behaviour and subantarctic climatic conditions are discussed.

African penguins as predators and prey – coping (or not) with change

African penguins Spheniscus demersus live in the Benguela and western Agulhas ecosystems off southern Africa. Their numbers decreased throughout the 20th century from at least 1.5 million to about 0.18 million adults, although different regional trends were apparent. They feed to a large extent on shoaling epipelagic fish, notably anchovy Engraulis capensis and sardine Sardinops sagax, and regional trends in the abundance of penguins are associated with trends in the abundance and distribution of these prey fish. Many first-time breeders emigrate from colonies where feeding or other conditions at the time are unfavourable to more favourable breeding localities. This has led to both the extinction and formation of colonies. Food now may limit colonies at relatively small sizes, a fact attributable to industrial fisheries reducing the densities of forage fish. African penguins share their habitat with several other predators, with which they compete for food and breeding space. One of these, the Cape fur seal Arctocephalus p. pusillus, increased through the 20th century to 1.5 – 2 million animals at its close. Reported observations of predation by fur seals on seabirds have increased in recent decades and threaten the continued existence of small colonies of penguins. Stochastic modelling suggests that colonies of 10 000 pairs have a 9% probability of extinction in 100 years, so smaller populations should be regarded as "Vulnerable". However, in a period of prolonged food scarcity off southern Namibia, the regional population decreased from more than 40 000 pairs in 1956 to about 1 000 pairs in 2000, and many colonies numbering less than 1 000 pairs became extinct. The minimum viable population for African penguins is currently considered to be >40 000 pairs, likely of the order of 50 000 pairs, a figure equivalent to its level in 2000. The chance of survival of the species through the 21st century is tenuous.

Intra-syllabic acoustic signatures used by the king penguin in parent-chick recognition: an experimental approach.

In king penguin colonies, several studies have shown that both parent-chick recognition and mate-pair recognition are achieved by acoustic signals. The call of king penguins consists of strong frequency modulations with added beats of varying amplitude induced by the two-voice generating process. Both the frequency modulation pattern and the two-voice system could play a role in the identification of the calling bird. We investigated the potential role of these features in individual discrimination. Experiments were conducted by playing back altered or reconstructed parental signals to the corresponding chick. The results proved that the king penguin performs a complex analysis of the call, using both frequency modulation and the two-voice system. Reversed or frequency-modulation-suppressed signals do not elicit any responses. Modifying the shape of the frequency modulation by 30 % also impairs the recognition process. Moreover, we have demonstrated for the first time that birds perform an analysis of the beat amplitude induced by the two-voice system to assess individual identity. These two features, which are well preserved during the propagation of the signal, seem to be a reliable strategy to ensure the accurate transmission of individual information in a noisy colonial environment.

Monitoring the concentration of N2O in the Fildes Peninsula, maritime Antarctica

Gases in the marine boundary layer in Fildes Peninsula, maritime Antarctica were sampled and analyzed for the first time. Sampling sites included areas covered by moss and lichen growth, penguin colonies and an area where scientific research stations are located. A total of 211 samples were analyzed for N2O concentrations, with an average of (321.33±3.07) nL/L. This is above the global average value of 314 nL/L. It is found that the N2O concentrations evidently increase during the summer months. Concentrations around the research stations are higher than at remote areas, indicating a potential source from human activities on the island. N2O concentrations at a large penguin colony on Barton Peninsula are the highest among the sampled areas. This may explain why N2O concentrations in Fildes Peninsula are higher than the global average. Our preliminary conclusions are that human activities and emissions from penguin dropping-amended soil and vegetation soil constitute the major sources of N2O in the maritime Antarctic atmosphere.

Detecting human bacterial contamination in Antarctic soils

The presence of non-indigenous microbial contaminants resulting from human faecal contamination of old and currently occupied base and field camp sites in South Victoria Land, Antarctica, was assessed by PCR amplification of extracted soil DNA using species-specific PCR primers. Positive controls (samples recovered from the environs of Scott Base, including the sewage outfall) gave strong signals with Escherichia coli primers whereas Clostridium clostridiiforme primers yielded a signal only with the sewage outfall sample. A comparison was made of PCR amplification results from samples from the abandoned Canada Glacier camp site, the Lake Fryxell summer camp site, the Cape Bird Adelie penguin colony and pristine sites from relatively inaccessible regions of the Taylor Valley. Results indicated a possible residual level of E. coli contamination in the abandoned Canada Glacier camp site, but no significant contamination of the currently occupied Lake Fryxell camp site. These data may provide indirect evidence for improved awareness and standards of waste handling and disposal over the past two decades of Dry Valley field research.

A method to assess population changes in king penguins: the use of a Geographical Information System to estimate area-population relationships

During the last decades, king penguin (Aptenodytes patagonicus) populations have been reported to increase throughout most of their breeding range. In this study, we compared the results obtained from direct counts of incubating king penguins with the results yielded by the estimation of the change in area occupied by breeding birds at the Ratmanoff king penguin colony at the Kerguelen Islands. The area of the colony was determined using a Geographical Information System with a georeferencing extension on aerial pictures taken in 1963, 1985 and 1998. Individual king penguin were counted on the same pictures or pictures taken on the same day. The overall population increase between 1963 and 1998 was 733% while the colony area increased by 677%. This study indicates that monitoring change in colony size is a good indicator for detecting and monitoring large population changes in king penguins, in particular for remote colonies. The discrepancy between the two results may be from two different kinds of bias. Firstly, there could be a possible error in the estimation of the area occupied by the colony resulting from the georeferencing of oblique pictures, and secondly, the density of king penguins may also change with population number. This method, which only requires high-altitude pictures, also reduces the possible disturbance to breeding made by low- to medium-altitude flights.

Adélie penguin colonies in eastern Prydz Bay: ‘biological indicators’ of exploration history and political change

AbstractTemporally and spatially increasing information on the distribution of Adélie penguin (Pygoscelis adeliae) breeding sites is used as an index of various national activities in eastern Prydz Bay, East Antarctica. Recorded instances of such sites are used to indicate both exploration and enhanced local knowledge. While Norwegians discovered the area (1935), and revisited it (1937), reports of penguins were minimal. The 1938 Ellsworth expedition added few details and the potential of Operation Highjump (1947) photographs to delimit breeding sites was never realised. Observations by Australian expeditioners from the mid-1950s onwards, supplemented to some extent by those from the Soviet Union, increased information substantially. When Davis station was established (January 1957), at least five breeding sites were known around eastern Prydz Bay. By 1973 this had increased to 23 or 24 sites, mostly north of the Sørsdal Glacier, which had apparently acted as a barrier to land-based exploration. Data available to 1980 showed 20 sites in the Vestfold Hills, added two in the Rauer Group, and omitted some recorded earlier. Ground surveys of the Vestfold Hills (November 1973) increased known sites slightly, discounted erroneous records, and massively increased numbers of individual colonies. In 1981 an air survey recognised 24 sites in the Vestfold Hills and increased those known to 47. In approximately the same period, official Soviet records showed perhaps four sites in the Vestfold Hills and another in the Rauer Group. Early reports provided poor estimates of breeding population sizes — totals of some 130,000 (or 174,200) pairs in the Vestfold Hills in 1973 are compared with perhaps 196,600 in 1981, with another 129,000 pairs to the south. By 1983 locations of breeding sites in the Vestfold Hills were well established, and this was achieved in southern Prydz Bay following publication of 1981 survey results.Progression of information regarding breeding sites in eastern Prydz Bay was slow. Initial Australian activities were slight following acceptance of its Antarctic Territory (1933). However, a Soviet Antarctic whaling fleet, uncertainty regarding American and Soviet intentions, and the imminent International Geophysical Year increased Australian interest. A station was established, local search areas expanded, and enhanced details regarding penguin breeding sites and colonies followed. Data reviews and surveys followed increasing international interest in southern ecosystems. Improved knowledge regarding the species' local populations reflected changing political agendas. Indeed, ‘knowledge’ itself gave early support to territorial claims. Participation in international surveys became an acceptable scientific endeavour, anticipated under Treaty agreements and promoted by associated organisations. In such fora, surveys and monitoring are expected, although not necessarily furthering the strength of existing claims.

Penguins use the two-voice system to recognize each other.

The sound-producing structure in birds is the syrinx, which is usually a two-part organ located at the junction of the bronchi. As each branch of the syrinx produces sound independently, many birds have two acoustic sources. Thirty years ago, we had anatomical, physiological and acoustical evidence of this two-voice phenomenon but no function was known. In songbirds, often these two voices with their respective harmonics are not activated simultaneously but they are obvious in large penguins and generate a beat pattern which varies between individuals. The emperor penguin breeds during the Antarctic winter, incubating and carrying its egg on its feet. Without the topographical cue of a nest, birds identify each other only by vocal means when switching duties during incubation or chick rearing. To test whether the two-voice system contains the identity code, we played back the modified call of their mate to both adults and also the modified call of their parents to chicks. Both the adults and the chicks replied to controls (two voices) but not to modified signals (one voice being experimentally suppressed). Our experiments demonstrate that the beat generated by the interaction of these two fundamental frequencies conveys information about individual identity and also propagates well through obstacles, being robust to sound degradation through the medium of bodies in a penguin colony. The two-voice structure is also clear in the call of other birds such as the king penguin, another non-nesting species, but not in the 14 other nesting penguins. We concluded that the two-voice phenomenon functions as an individual recognition system in species using few if any landmarks to meet. In penguins, this coding process, increasing the call complexity and resisting sound degradation, has evolved in parallel with the loss of territoriality.

Ammonium and potassium in snow around an emperor penguin colony

Snow samples taken at various distances from the emperor penguin (Aptenodytes forsteri) colony near Halley station were analysed by ion chromatography. Extremely high ammonium concentrations were encountered at the colony itself, but fell off sharply with distance from the colony, reaching background levels within a few kilometres of the colony. A seasonal effect was also seen, with the highest concentrations found in spring when the colony was at its most active. Levels of potassium and other sea-salt ions were also elevated near the colony. The ratio of sodium to potassium was lower than that found in bulk seawater, and closer to that found in the penguin's food source, indicating that the increased concentrations are due to emissions from the penguins and not merely to the proximity of open seawater to the site. The colony thus has a significant effect on the composition of the nearby snow, but this effect is strongly localised and is not likely to significantly influence snow chemistry at inland ice core drilling sites.

Factors influencing growth of the African penguin colony at Boulders, South Africa, 1985–1999

This paper reports on growth of the Boulders colony of African penguins Spheniscus demersus from inception in 1985 to the present. More than 900 pairs now breed there. Growth of the colony slowed in 1995 and 1996 and reversed in 1998, coinciding with periods of low abundance of Cape anchovy Engraulis capensis off South Africa. In December 1996, penguins were excluded from a portion of land where they had formerly bred. They responded by increasing the density of their nests in other areas and expanding their area of breeding longshore. These patterns indicate that food and not space are currently controlling colony growth rate. Much of the colony growth probably results from immigration of first-time breeders from other colonies. Of immigrants, 70–80% may be from Dyer Island to the south-east, where numbers of penguins have decreased. Boulders also is frequently visited by penguins from other colonies, and by rehabilitated birds.