King Penguin Colony Research Articles

Investigating two consecutive catastrophic breeding seasons in a large king penguin colony

Large-scale breeding failures, such as offspring die-offs, can disproportionately impact wildlife populations that are characterized by a few large colonies. However, breeding monitoring—and thus investigations of such die-offs—is especially challenging in species with long reproductive cycles. We investigate two unresolved dramatic breeding failures that occurred in consecutive years (2009 and 2010) in a large king penguin Aptenodytes patagonicus colony, a long-lived species with a breeding cycle lasting over a year. Here we found that a single period, winter 2009, was likely responsible for the occurrence of breeding anomalies during both breeding seasons, suggesting that adults experienced poor foraging conditions at sea at that time. Following that unfavorable winter, the 2009 breeding cohort—who were entering the late stage of chick-rearing—immediately experienced high chick mortality. Meanwhile, the 2010 breeding cohort greatly delayed their arrival and egg laying, which would have otherwise started not long after the winter. The 2010 breeding season continued to display anomalies during the incubation and chick-rearing period, such as high abandonment rate, long foraging trips and eventually the death of all chicks in winter 2010. These anomalies could have resulted from either a domino-effect caused by the delayed laying, the continuation of poor foraging conditions, or both. This study provides an example of a large-scale catastrophic breeding failure and highlights the importance of the winter period on phenology and reproduction success for wildlife that breed in few large colonies.

Developing UAV Monitoring of South Georgia and the South Sandwich Islands’ Iconic Land-Based Marine Predators

Many remote islands present barriers to effective wildlife monitoring in terms of challenging terrain and frequency of visits. The sub-Antarctic islands of South Georgia and the South Sandwich Islands are home to globally significant populations of seabirds and marine mammals. South Georgia hosts the largest breeding populations of Antarctic fur seals, southern elephant seals and king penguins as well as significant populations of wandering, black-browed and grey-headed albatross. The island also holds important populations of macaroni and gentoo penguins. The South Sandwich Islands host the world’s largest colony of chinstrap penguins in addition to major populations of Adélie and macaroni penguins. A marine protected area was created around these islands in 2012 but monitoring populations of marine predators remains a challenge, particularly as these species breed over large areas in remote and often inaccessible locations. During the 2019/20 austral summer, we trialled the use of an unoccupied aerial vehicle (UAV; drone) to monitor populations of seals, penguins and albatross and here we report our initial findings, including considerations about the advantages and limitations of the methodology. Three extensive southern elephant seal breeding sites were surveyed with complete counts made around the peak pupping date, two of these sites were last surveyed 24 years ago. A total of nine islands, historically recorded as breeding sites for wandering albatross, were surveyed with 144 fledglings and 48 adults identified from the aerial imagery. The UAV was effective at surveying populations of penguins that nest on flat, open terrain, such as Adélie and chinstrap penguin colonies at the South Sandwich Islands, and an extensive king penguin colony on South Georgia, but proved ineffective for monitoring macaroni penguins nesting in tussock habitat on South Georgia as individuals were obscured or hidden by vegetation. Overall, we show that UAV surveys can allow regular and accurate monitoring of these important wildlife populations.

Combined effects of glacial retreat and penguin activity on soil greenhouse gas fluxes on South Georgia, sub-Antarctica

The effects of soil succession after glacial retreat and fertilisation by marine animals are known to have major impacts on soil greenhouse gas (GHG) fluxes in polar terrestrial ecosystems. While in many polar coastal areas retreating glaciers open up new ground for marine animals to colonise, little is known about the combination of both factors on the local GHG budget. We studied the magnitude of GHG fluxes (CO2, CH4 and N2O) on the combined effect of glacial retreat and penguin-induced fertilisation along a transect protruding into the world’s largest King Penguin (Aptenodytes patagonicus) colony at Saint Andrews Bay on sub-Antarctic South Georgia. GHG production and consumption rates were assessed based on laboratory incubations of intact soil cores and nutrients and water additional experimental incubations. The oldest soils along the transect show significant higher contents of soil carbon, nutrients and moisture and were strongly influenced by penguin activity. We found a net CH4 consumption along the entire transect with a marked decrease within the penguin colony. CO2 production strongly increased along the transect, while N2O production rates were low near the glacier front and increased markedly within the penguin colony. Controlled applications of guano resulted in a significant increase in CO2 and N2O production, and decrease in CH4 consumption, except for sites already strongly influenced by penguin activity. The results show that soil microbial activity promptly catalyses a turnover of soil C and atmospheric methane oxidation in de-glaciated forelands. The methane oxidizers, however, may increase relatively slowly in their capacity to oxidise atmospheric CH4. Results show also that the increase of nutrients by penguins reduces CH4 oxidation whereas N2O production is greatly increased. A future expansion of penguins into newly available ice-free polar coastal areas may therefore markedly increase the local GHG budget.

A rare observation of group prey processing in wild leopard seals (Hydrurga leptonyx)

Cooperative feeding is often observed among predators with strong social bonds; however, it is unexpected in solitary predators. During 2016, several mass predation events were witnessed in St Andrews Bay and Right Whale Bay, South Georgia, where up to 36 leopard seals (Hydrurga leptonyx) were seen feeding together at king penguin (Aptenodytes patagonicus) colonies. Three post-mortem prey-processing events were observed where two leopard seals actively fed on the same carcass in an unusual display of tolerance for a species where anti-social behaviour is the norm. The seals were observed repeatedly tearing adult king penguins between themselves, while floating alongside each other at the surface of the water. This is the first record of co-feeding in this difficult-to-study species; however, it is expected that the behaviour is rare within the population. We propose that the high density of predators combined with the readily available prey, makes it costlier to defend a kill than it is to tolerate kleptoparasitism. It is unclear whether this behaviour shows cooperative feeding, which would likely enable more efficient prey processing: by holding the prey in their jaws, each seal provides an anchor on the prey that others can pull against to stretch and tear it.

Massive decline of the world’s largest king penguin colony at Ile aux Cochons, Crozet

AbstractKing penguins (Aptenodytes patagonicus Miller) are major consumers in the Southern Ocean. The colony at Ile aux Cochons, Iles Crozet, in the southern Indian Ocean was known in the 1980s as the largest king penguin colony and the second largest penguin colony in the world. However, there have not been any recent estimates of this colony. Aerial photographs taken from a helicopter, and satellite images were used to report on changes in the colony and population sizes over the past 50 years. The colony has declined by 88% over the past 35 years, from c. 500 000 pairs to 60 000 pairs. The possible causes of this decline were explored but no plausible explanation for such an unprecedented decrease in penguin populations was found. The study highlights the use of satellite imagery as a non-invasive technique for population monitoring, and stresses the need for further research on the causes of this alarming trend in this colony.

Structural organisation and dynamics in king penguin colonies

During breeding, king penguins do not build nests, however they show strong territorial behaviour and keep a pecking distance to neighbouring penguins. Penguin positions in breeding colonies are highly stable over weeks and appear regularly spaced, but thus far no quantitative analysis of the structural order inside a colony has been performed. In this study, we use the radial distribution function to analyse the spatial coordinates of penguin positions. Coordinates are obtained from aerial images of two colonies that were observed for several years. Our data demonstrate that the structural order in king penguin colonies resembles a 2D liquid of particles with a Lennard-Jones-type interaction potential. We verify this using a molecular dynamics simulation with thermally driven particles, whereby temperature corresponds to penguin movements, the energy well depth ϵ of the attractive potential corresponds to the strength of the colony-forming behaviour, and the repulsive zone corresponds to the pecking radius. We can recapitulate the liquid disorder of the colony, as measured by the radial distribution function, when the particles have a temperature of several (1.4–10) and a normally distributed repulsive radius. To account for the observation that penguin positions are stable over the entire breeding period, we hypothesize that the liquid disorder is quenched during the colony formation process. Quenching requires the temperature to fall considerably below 1 , which corresponds to a glass transition, or the repulsion radius to exceed the distance between neighbouring penguins, which corresponds to a jamming transition. Video recordings of a breeding colony together with simulations suggest that quenching is achieved by a behavioural motility arrest akin to a glass transition. We suggest that a liquid disordered colony structure provides an ideal compromise between high density and high flexibility to respond to external disturbances that require a repositioning of penguins.

Soundscape stability in king penguin colonies

King penguin colonies present an acoustically rich environment due to the highly vocal nature of these birds and the large abundance of birds within a colony (100.000 + ). Individual identification in adults and chicks is based on vocal signals. Penguins can recognize the call of their partner or chick even among thousands of calling individuals. However, the range of such identification is limited to a few meters, 8.8 m on average in the colony. In spite of the fact that king penguins are famous for their highly developed acoustic abilities, little is known regarding the overall acoustic colony structure. Using a distributed synchronized microphone array, we collected soundscape information over several months at several locations. We find location specific features in the soundscape that are stable over several weeks, regardless of environmental conditions and only require short integration time. We explore if current acoustic indices are able to capture these features, if soundscape stability information might be useful for navigation and if this information can be associated with current colony structure and spatial use.

Dispersal in the sub-Antarctic: king penguins show remarkably little population genetic differentiation across their range.

BackgroundSeabirds are important components of marine ecosystems, both as predators and as indicators of ecological change, being conspicuous and sensitive to changes in prey abundance. To determine whether fluctuations in population sizes are localised or indicative of large-scale ecosystem change, we must first understand population structure and dispersal. King penguins are long-lived seabirds that occupy a niche across the sub-Antarctic zone close to the Polar Front. Colonies have very different histories of exploitation, population recovery, and expansion.ResultsWe investigated the genetic population structure and patterns of colonisation of king penguins across their current range using a dataset of 5154 unlinked, high-coverage single nucleotide polymorphisms generated via restriction site associated DNA sequencing (RADSeq). Despite breeding at a small number of discrete, geographically separate sites, we find only very slight genetic differentiation among colonies separated by thousands of kilometers of open-ocean, suggesting migration among islands and archipelagos may be common. Our results show that the South Georgia population is slightly differentiated from all other colonies and suggest that the recently founded Falkland Island colony is likely to have been established by migrants from the distant Crozet Islands rather than nearby colonies on South Georgia, possibly as a result of density-dependent processes.ConclusionsThe observed subtle differentiation among king penguin colonies must be considered in future conservation planning and monitoring of the species, and demographic models that attempt to forecast extinction risk in response to large-scale climate change must take into account migration. It is possible that migration could buffer king penguins against some of the impacts of climate change where colonies appear panmictic, although it is unlikely to protect them completely given the widespread physical changes projected for their Southern Ocean foraging grounds. Overall, large-scale population genetic studies of marine predators across the Southern Ocean are revealing more interconnection and migration than previously supposed.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0784-z) contains supplementary material, which is available to authorized users.

Responses of king penguinAptenodytes patagonicusadults and chicks to two food-related odours

Increasing evidence suggests that penguins are sensitive to dimethyl sulphide (DMS), a scented airborne compound that a variety of marine animals use to find productive areas of the ocean where prey is likely to be found. Here we present data showing that king penguins Aptenodytes patagonicus are also sensitive to DMS. We deployed DMS on a lake near a king penguin colony at Ratmanoff beach in the Kerguelen archipelago. We also presented DMS to ‘sleeping’ adults on the beach. On the lake, penguins responded to the DMS deployments by swimming more, while on the beach, penguins twitched their heads and woke up more for the DMS than for the control presentations. Interestingly, penguins did not respond to cod liver oil deployments on the lake; mirroring at-sea studies of other penguins. Although at-sea studies are needed to confirm that king penguins use DMS as a surface cue that informs them of productivity under the water, this study is an important first step in understanding how these birds locate prey over significant distances.

Basal Metabolic Rate of the Black-Faced Sheathbill (Chionis minor): Intraspecific Variation in a Phylogenetically Distinct Island Endemic.

Metabolic rate is a fundamental characteristic of all organisms. It covaries most significantly with activity, body mass, seasonality, and temperature. Nonetheless, substantial additional variation in metabolic rate, especially either resting rate or basal rate, is associated with a range of factors including phylogenetic position, ecological distinctiveness, range position, and diet. Understanding this variation is a key goal of physiological ecology. The black-faced sheathbill is a phylogenetically distinct, high-latitude, island-endemic bird occurring exclusively on several archipelagos in the southern Indian Ocean. Here we examined the idea that the unique phylogenetic position and ecology of the black-faced sheathbill may lead to a basal metabolic rate (BMR) different from that predicted by its body mass. When compared with BMR data available for all birds and a subset of island species, it was clear that the BMR of the black-faced sheathbill on subantarctic Marion Island, estimated at 15°C using indirect calorimetry (2.370 ± 0.464 W, mean ± SD; n = 22), for a group of birds with a mean mass of 459 ± 64 g, is no different from that expected based on body mass. However, variation in BMR, associated with habitat use and diet, even when correcting for variation in mass, was found. Sheathbills foraging year-round in comparatively resource-rich king penguin colonies have a higher BMR (2.758 ± 0.291 W, n = 12) than sheathbills that split their foraging between rockhopper penguin colonies and the intertidal zone (2.047 ± 0.303 W, n = 10), which are poorer in resources. Because these populations coexist at relatively small spatial extents (the entire island is 290 km(2)), other factors seem unlikely as causes of this variation.

Bernard Stonehouse (1926-2014)

Bernard Stonehouse's long and varied career commenced with pioneering studies on the breeding habits of the two species of Aptenodytes penguins. As well as undertaking fieldwork in remote places, he taught in both schools and universities, wrote academic and popular books, and latterly led a long-term study on the ecological impact of tourism in Antarctica. Stonehouse was born on 1 May 1926 at Kingston upon Hull. After learning to fly in the Fleet Air Arm he served as a meteorologist with the Falklands Islands Dependencies Survey (now British Antarctic Survey). He was posted in February 1947 to the base at Stonington Island, in Marguerite Bay, where during his second year he discovered a colony of Emperor Penguins Aptenodytes fosteri on the tiny Dion Islands. That summer the pack-ice remained solid and the base could not be relieved. Stonehouse was able to put his third, enforced, winter to good use by spending 2 months on the Dion Islands where, camped in a tent with temperatures dropping to −40 °C, he made the first detailed study of the breeding habits of the Emperor Penguin, a species that lays its egg in the middle of the Antarctic winter. After his return to Britain, Stonehouse graduated in zoology and geology at University College, London, and moved to the Edward Grey Institute of Field Ornithology at Oxford University. He received special dispensation to spend 18 months at South Georgia to study the breeding behaviour of the King Penguin Aptenodytes patagonicus. With Nigel Bonner as assistant, he set up camp in a garden shed near a large King Penguin colony and was able to elucidate the species' unusual protracted breeding season. In 1957 Stonehouse was appointed leader of the British Ornithologists' Union Centenary Expedition to Ascension Island which would study the breeding cycles and breeding seasons of 11 species of seabirds and four species of introduced landbirds living in a near tropical environment. Of particular interest were the Sooty Tern (locally Wideawake Tern) Onychoprion fuscatus, Yellow-billed Tropic Bird Phaethon lepturus, Red-billed Tropic Bird P. aethereus and Brown Booby Sula leucogaster which have unusual shorter than annual breeding cycles. The team on Ascension Island consisted of Stonehouse, his wife Sally as camp manager, Douglas Dorward and Philip Ashmole, with shorter visits by Richard Allan, Michael Cullen and Eric Duffey. Stonehouse was appointed senior lecturer at the University of Canterbury, Christchurch, New Zealand, in 1960. He was able to return to Antarctica and continue the study of penguins. Aerial surveys were used to discover new colonies of both Adélie and Pygoscelis adeliae Emperor Penguins and record annual population fluctuations. An important strand of Stonehouse's research was the impact of human activity on animal populations and he persuaded the New Zealand and American authorities to restrict visits to penguin colonies. He was also concerned about the emergence of Antarctic tourism but he soon realized that tourists had more regard for wildlife than many of the administrators and scientists working in Antarctica. In 1972 Stonehouse moved to the University of Bradford to set up a School of Studies in Environmental Sciences. Eleven years later, he moved to Cambridge and, from 1983 to 1992, was editor of the Polar Record. In 1991, he initiated Project Antarctic Conservation to investigate the development and impact of the growing shipborne tourism. He noted that ‘On the whole, the tourists have done far less damage than some of the scientists’. Bernard Stonehouse was known to his colleagues as an efficient and unflappable organizer with an aptitude for improvisation, and by his many students for his ability to make them think critically and for unselfishly sharing his own knowledge. The International Steering Committee of the International Penguin Conferences recognized him with a Lifetime Achievement Award to celebrate his achievements in a lifetime of penguin research, the New Zealand Antarctic Society awarded him their Voycey Trophy for Antarctic Conservation and he was given an honorary D.Sc. by the University of Hull. The BOU awarded Bernard the Union Medal in 1971 (Ibis 1971, 113: 404–405). He is generally credited as the true father of penguin biology.

Spatial heterogeneity as a genetic mixing mechanism in highly philopatric colonial seabirds.

How genetic diversity is maintained in philopatric colonial systems remains unclear, and understanding the dynamic balance of philopatry and dispersal at all spatial scales is essential to the study of the evolution of coloniality. In the King penguin, Aptenodytes patagonicus, return rates of post-fledging chicks to their natal sub-colony are remarkably high. Empirical studies have shown that adults return year after year to their previous breeding territories within a radius of a few meters. Yet, little reliable data are available on intra- and inter-colonial dispersal in this species. Here, we present the first fine-scale study of the genetic structure in a king penguin colony in the Crozet Archipelago. Samples were collected from individual chicks and analysed at 8 microsatellite loci. Precise geolocation data of hatching sites and selective pressures associated with habitat features were recorded for all sampling locations. We found that despite strong natal and breeding site fidelity, king penguins retain a high degree of panmixia and genetic diversity. Yet, genetic structure appears markedly heterogeneous across the colony, with higher-than-expected inbreeding levels, and local inbreeding and relatedness hotspots that overlap predicted higher-quality nesting locations. This points towards heterogeneous population structure at the sub-colony level, in which fine-scale environmental features drive local philopatric behaviour, while lower-quality patches may act as genetic mixing mechanisms at the colony level. These findings show how a lack of global genetic structuring can emerge from small-scale heterogeneity in ecological parameters, as opposed to the classical model of homogeneous dispersal. Our results also emphasize the importance of sampling design for estimation of population parameters in colonial seabirds, as at high spatial resolution, basic genetic features are shown to be location-dependent. Finally, this study stresses the importance of understanding intra-colonial dispersal and genetic mixing mechanisms in order to better estimate species-wide gene flows and population dynamics.

Non-Target Species Management for the Macquarie Island Pest Eradication Project

Author(s): Springer, Keith; Carmichael, Noel | Abstract: Mitigation of non-target species impacts is a key challenge of the Macquarie Island Pest Eradication Project (MIPEP). The project aims to eradicate rodents and European rabbits from sub-Antarctic Macquarie Island through the aerial application of cereal-based brodifacoum bait, followed by a hunting program targeting surviving rabbits. Aerial baiting was attempted in winter 2010 but postponed due to sustained adverse weather that suspended helicopter operations. Following limited baiting in 2010 (10% of the island), non-target mortality of 960 individuals across 6 (of 27) seabird and duck species was recorded. In response, the Australian and Tasmanian governments conducted a review of the project. The review established that some species would be adversely affected by the project in the short-term, but that the island’s ecosystem and most other island species would substantially benefit from pest eradication, confirming the assessments in the Environmental Impact Statement prepared prior to the operation. Enhanced mitigation measures were recommended to minimise non-target species impacts. Of several potential mitigation measures assessed, two principal measures were adopted: releasing Rabbit Haemorrhagic Disease Virus to reduce the rabbit population prior to baiting, thus minimising the number of rabbit carcasses containing poison residues available for consumption by scavengers; and increasing the effort of field teams during and after baiting to remove carcasses (the primary 2010 strategy), in an attempt to minimise the exposure of scavengers to toxic residues. Baiting resumed in May 2011 and two island-wide drops were completed by July 2011. Seabird mortality was monitored, with over 1,460 dead birds of the same species found that were affected in 2010, primarily scavenging seabirds such as kelp gulls, giant petrels, and skua. No species was considered to have sustained impacts that threatened the viability of the local population. King penguin colonies were closely monitored during helicopter over-flights and only minor and transitory impacts were observed. Wandering albatross nests were cleared of bait and chicks were not affected. No marine mammal impacts were recorded. If successful, the MIPEP will be the largest and most complex sub-Antarctic island rabbit and rodent eradication yet undertaken.

Introduced black rats Rattus rattus on Ile de la Possession (Iles Crozet, Subantarctic): diet and trophic position in food webs

Rats introduced on islands can affect ecosystem structure and function by feeding on terrestrial plants and both marine and terrestrial animals. The diet and trophic position of Rattus rattus introduced on Ile de la Possession (Iles Crozet) was assessed from two sites, according to the presence or absence of a king penguin colony. We used three complementary assays: macroanalyses of the stomach, faecal microhistology, and stable isotope analyses of δ15N/δ13C in liver. Near the rookery, spermatophytes contributed on average 50% (confidential interval: 23–75) to the diet based on isotopes, mainly consisting in reproductive parts of Poa spp., Agrostis magellanica, and Cerastium fontanum identified in faeces. Terrestrial animal preys were represented by insects that contributed 25% (0–56) in isotopes, dominated in faeces by caterpillars of Pringleophaga spp. and adult weevils. Bird remains were found in faeces, forming 18% (6–30) of isotopes. Terrestrial earthworms contributed to 7% (0–21), with chaetae observed in faeces. On the other site, spermatophytes represented 62% (51–73) of assimilated food in rats’ livers, mainly formed by Poaceae and Acaena magellanica, insects by caterpillars [24% (10–39)], and terrestrial earthworms [13% (2–23)]. Our results suggest that rats, which were found at the top of terrestrial food chains, may have a direct role on a such simplified ecosystem, by preying on the most abundant and largest body-sized terrestrial invertebrates,—e.g. the keystone species Pringleophaga spp.—, and by feeding on both reproductive and vegetative parts of autochthonous and introduced plants. The discrepancies and usefulness of employing both isotopes and faecal analyses are discussed.

Do penguins dare to walk at night? Visual cues influence king penguin colony arrivals and departures

Orientation based on visual cues can be extremely difficult in crowded bird colonies due to the presence of many individuals. We studied king penguins (Aptenodytes patagonicus) that live in dense colonies and are constantly faced with such problems. Our aims were to describe adult penguin homing paths on land and to test whether visual cues are important for their orientation in the colony. We also tested the hypothesis that older penguins should be better able to cope with limited visual cues due to their greater experience. We collected and examined GPS paths of homing penguins. In addition, we analyzed 8 months of penguin arrivals to and departures from the colony using data from an automatic identification system. We found that birds rearing chicks did not minimize their traveling time on land and did not proceed to their young (located in creches) along straight paths. Moreover, breeding birds' arrivals and departures were affected by the time of day and luminosity levels. Our data suggest that king penguins prefer to move in and out of the colony when visual cues are available. Still, they are capable of navigating even in complete darkness, and this ability seems to develop over the years, with older breeding birds more likely to move through the colony at nighttime luminosity levels. This study is the first step in unveiling the mysteries of king penguin orientation on land.

Relating Demographic Performance to Breeding-Site Location in the King Penguin

Abstract. In colonial species, it is often assumed that locations in the center of the colony are of highest quality and provide highest breeding success. We tested this prediction, known as the “central-periphery model,” in a King Penguin colony in the subantarctic Crozet Archipelago. Breeding activity and survival of 150 penguins, ftted with transponder tags, were monitored over an entire breeding season. Among these 150 bird s, 50 bred on t he slope at the upper periphery of the colony, where the rates of predation and parasitism by ticks were high. fifty birds bred in the center of the colony, where rates of predation and tick parasitism were low, and 50 bred at the lower end of the colony, where the rate of tick parasitism was low but predation and fooding were important risks. We predicted that the center of the colony should provide the safest breeding place and consequently be characterized by the highest breeding success and be used by the highest-quality individuals. Yet we found that penguins b...

Nocturnal predation of king penguins by giant petrels on the Crozet Islands

Dietary segregation of sympatric seabirds in the Southern Ocean is partly linked to differences in their foraging techniques. We have investigated the activity of giant petrels (Macronectes spp.) in a king penguin (Aptenodytes patagonicus) colony day and night during the austral winter of 2001 on the Crozet Islands. Using an automatic identification system and an infrared video camera, we followed 15 petrels tagged with micro transponders. Our data show that giant petrels predate king penguin chicks during the night. The activity of giant petrels is even slightly higher during nighttime than during the day. In addition, our data show a higher nocturnal activity by northern giant petrels (M. halli) than by southern giant petrels (M. giganteus). These unexpected results raise questions concerning visual adaptations to nocturnal foraging in giant petrels and their potential impact on the sleep, vigilance and creching behavior of penguin chicks.

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.

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.

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.