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Modelling marine predator foraging habitats is a widespread research approach for projecting species responses to a rapidly changing Southern Ocean. Yet a key remaining challenge is to understand how changing prey biomass within foraging habitats could affect predator foraging success. Quantifying this using observed prey information is challenging given a paucity of synoptic data. Here, we investigated whether prey biomass from a mechanistic model, could provide useful predictions of pre-breeding arrival body mass of macaroni penguins (Eudyptes chrysolophus) from Marion Island, a standard metric of predator foraging success, measured over a 20-year period. In testing this, we used a spatially iterative correlation approach between predicted prey biomass and observed penguin arrival body mass, allowing likely foraging areas to emerge in regions most frequently associated with significant correlations. We then considered whether the distribution of these emergent foraging areas is consistent with tracking-derived foraging distributions for this species and island. Our results indicated emergent foraging areas where prey biomass was most often correlated with arrival body mass were located within expected and observed foraging ranges. Further, variability in prey biomass, within these emergent foraging areas provided reasonable predictions of annual penguin arrival body mass and outperformed metrics of primary production within these foraging areas. Our findings demonstrate that mechanistic models can provide biologically meaningful representations of difficult-to-observe prey, and can predict predator foraging success. This work could improve understanding of predator responses in a changing habitat.

Elephant Island sits on the front lines of ecological change in the Scotia Arc region, but most of the island has remained unsurveyed for nearly 50 years. As a result, there has been no way to establish whether changes on the island reflect those to the south along the Western Antarctic Peninsula or whether, in contrast, populations have remained stable, as on the more northerly South Sandwich Islands. At the core of the Chinstrap Penguin (Pygoscelis antarcticus) breeding range, at the southern edge of the Macaroni Penguin (Eudyptes chrysolophus) and (very recently) King Penguin (Aptenodytes patagonicus) ranges, at the northern limit of the Adélie Penguin (Pygoscelis adeliae) range, and in an area where Gentoo Penguin (Pygoscelis papua) populations are expanding southward, Elephant Island is situated at a unique ecological crossroads, hosting both sub-Antarctic and Antarctic seabirds, the former of which may be responding favorably to the very same climate changes that imperil the latter. Fortunately, an exhaustive census of the island in 1970–71 provides a rigorous baseline against which to document ecological change. Here, we report on the first complete survey of the island since 1970–71, conducted from January 9–20, 2020. Results indicate a decrease in Chinstrap Penguin populations, a doubling of Gentoo Penguins, a stable number of Macaroni Penguins, continuing occupancy by a few Adélie Penguins, and evidence of King Penguin breeding expansion. Our findings demonstrate that Elephant Island's seabird community has changed dramatically over the past five decades and that these changes appear to be ongoing. [ABSTRACT FROM AUTHOR]

As nonhuman animals age, geriatric individuals require additional care and veterinary support to ensure their well being. The focus on lifelong care is a relatively newer approach when providing good welfare, and few studies have examined how veterinary care impacts behavior at different ages or how best to accommodate geriatric individuals in zoos. The objectives of this study were to (a) assess both the immediate and long-term (one year later) behavioral impacts of cataract removal for macaroni (Eudyptes chrysolophus) and southern rockhopper (Eudyptes chrysocome) penguins; (b) compare the behavior of penguins following cataract surgery to that of other conspecifics in the same habitat; and (c) monitor the impacts of cataract surgery on swimming behavior using time-depth recorders. Individual responses to cataract removal differed in direction and magnitude, and these mixed results highlight that welfare is experienced and thus measured at the individual level. Positive responses included increased habitat use, increased time spent swimming, and increased rates of affiliative interactions. This study highlights the importance of assessing welfare impacts of veterinary interventions on geriatric individuals. [ABSTRACT FROM AUTHOR]

Highlights • We evaluated welfare effects of wearing time-depth recorders for penguins in a zoo. • Four penguin species showed few behavioral responses to wearing devices. • The penguins also required little to no time to habituate to wearing devices. • The devices, which are often used at sea, worked well in a freshwater pool. • Time-depth recorders can be used to monitor penguin welfare in zoos and aquariums. Abstract The time that penguins devote to aquatic behaviors likely has important implications for their welfare in zoos and aquariums. For decades, field researchers have used time-depth recorders (TDRs) to understand the behavior of penguins at sea. However, zoos and aquariums have rarely used these tools, and wearing devices can potentially affect animals negatively by causing discomfort or imposing energetic costs. We evaluated the long-term behavioral responses of 27 penguins (n = 8 king penguins, Aptenodytes patagonicus ; n = 3 gentoo penguins, Pygoscelis papua ellsworthi ; n = 8 macaroni penguins, Eudyptes chrysolophus ; and n = 8 southern rockhopper penguins, Eudyptes chrysocome) before, during, and after wearing TDRs in an ABA study design. Our novel method involved affixing the TDRs to a custom-designed cradle and securing them on the penguins using flipper bands, which the penguins were accustomed to wearing for identification. The experiment was repeated four times, and we used a total of 399.5 h of behavioral observations to evaluate the effects of the TDRs on locomotor, comfort, and social behaviors. We also conducted observations with a second set of penguins (two of each species) naïve to wearing TDRs to evaluate their acute responses following application of the devices. Finally, we conducted validation tests to assess the accuracy of TDRs in a freshwater pool. Penguins observed immediately after the devices were applied to their flipper bands for the first time showed little device-directed behavior. However, there were some individual differences, suggesting that zoos and aquariums should carefully monitor initial behavioral responses to TDRs. In the long term, wearing TDRs had few effects on the behavior of the penguins. The penguins displayed almost no device-directed behavior, and there were few statistically significant differences in their behavior across the three study conditions. Seasonal changes and penguin weight likely explained the increase in movement king penguins demonstrated after wearing TDRs (F 2,58 = 4.34, p = 0.02). King penguins also showed a small increase in agonistic behavior while wearing TDRs (F 2,73 = 3.81, p = 0.03), a difference that may have been related to mating competition during the breeding season. Our results indicate that these flipper-mounted TDRs had few effects on the penguins, while providing valuable information about 24-hour use of aquatic resources in their freshwater habitats. [ABSTRACT FROM AUTHOR]

Dietary studies of marine predators offer an immediate signal of foodweb changes occurring at lower trophic levels, and therefore are often used to assess the ecosystem status of marine systems. Conventionally, these studies are based on morphological analysis of prey remains in stomach contents, involving invasive and destructive techniques to collect samples. More recently, the number of dietary studies based on less invasive biochemical and molecular approaches has dramatically increased. However, all three methods, morphological, biochemical and molecular, have well-documented limitations for resolving taxonomy, temporal variation or biomass composition. In this study, we minimise these limitations by considering multiple techniques in combination. As a case study, we report the target prey species and diet composition of a marine predator that has been used to assess annual change in managed fishing areas for several decades, the macaroni penguin Eudyptes chrysolophus . We use biochemical (stable isotope) and molecular (DNA) analysis of faecal samples collected across the different phases of a single breeding season, and compare the resolved diet to a 26-year dataset of stomach contents collected from a closely located colony (0.25 km apart) that exploits identical foraging grounds. Molecular analysis increased the known target prey species for this highly monitored population by 31%, including a fish species of commercial importance. Biochemical analysis detected subtle changes in the proportion of fish and krill in the diet, demonstrating promising opportunities for using a combined molecular and biochemical method to assess inter-annual foodweb changes at lower trophic levels. The combined approach offers a less invasive sampling methodology, compared to morphological analysis, and provides more information regarding prey species diversity and the overall trophic signature of the diet. Further studies are required to examine the feasibility of using this approach for long-term dietary studies of different marine predator species. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms that link prey availability to predator behaviour and population change is central to projecting how a species may respond to future environmental pressures. We documented the behavioural responses and breeding investment of macaroni penguins Eudyptes chrysolophus across five breeding seasons where local prey density changed by five-fold; from very low to highly abundant. When prey availability was low, foraging trips were significantly longer and extended overnight. Birds also foraged farther from the colony, potentially in order to reach more distant foraging grounds and allow for increased search times. These extended foraging trips were also linked to a marked decrease in fledgling weights, most likely associated with reduced rates of provisioning. Furthermore, by comparing our results with previous work on this population, it appears that lowered first-year survival rates associated, at least partially, with fledging masses were also evident for this cohort. This study integrates a unique set of prey density, predator behaviour and predator breeding investment data to highlight a possible behavioural mechanism linking perturbations in prey availability to population demography. [ABSTRACT FROM AUTHOR]

Plumage aberrations, such as leucism, isabellinism, albinism and melanism, are hereditary and are caused by irregularities in the formation of melanin. This paper presents opportunistic observations of plumage aberrations in 15 Macaroni Penguins Eudyptes chrysolophus at sub-Antarctic Marion Island during 2008-2016. Across five colonies, full and partial leucism, isabellinism and partial melanism were recorded. Plumage aberration in Macaroni Penguins is rarely reported elsewhere in the world. The relatively high number of recorded individuals at Marion Island, in conjunction with limited mixing between global Macaroni Penguin colonies, suggests that a relatively high proportion of the population is entrained with this genetic predisposition. [ABSTRACT FROM AUTHOR]

Inter-annual variability in diet during crèche (December to February) over 22 years (1989-2010) was examined for gentoo penguins Pygoscelis papua breeding at Bird Island, South Georgia (54°00′S, 38°03′W). Overall, diets comprised 51% crustaceans and 49% fish by mass. Crustaceans were present in 89% of samples and were the main prey (>50% by mass) in 10 years of the study. Antarctic krill Euphausia superba were present in 85% of all diet samples. Fish were present in 79% of samples and were the main prey in 12 years, with Champsocephalus gunnari and Lepidonotothen larseni the most frequently recorded species, in 51 and 33% of samples, respectively. The energy or mass of krill in the diet was the most reliable predictor of breeding success (the number of chicks fledged per breeding pair); the correlation between model-predicted and observed values was 0.58. We compared annual patterns of gentoo penguin diet variability with those of macaroni penguins Eudyptes chrysolophus breeding at the same location. Our results suggest that the availability of krill is a key source of diet variability for both species, but their diets indicate that gentoo penguins are generalist predators (feeding on pelagic and bentho-pelagic prey), while macaroni penguins are krill specialists (feeding on pelagic prey). Differences in the response to variability in key prey species is an important factor separating the ecological niches of these two sympatric krill predators. [ABSTRACT FROM AUTHOR]

• Modelled mid-trophic prey biomass may be useful to predict predator foraging success. • Tested if prey biomass and predator foraging success was correlated in foraging areas. • Identified foraging areas by correlating prey biomass and predator foraging success. • Emergent foraging areas did occur within observed foraging distributions. • We highlight the applicability of prey models in marine predator foraging ecology. Modelling marine predator foraging habitats is a widespread research approach for projecting species responses to a rapidly changing Southern Ocean. Yet a key remaining challenge is to understand how changing prey biomass within foraging habitats could affect predator foraging success. Quantifying this using observed prey information is challenging given a paucity of synoptic data. Here, we investigated whether prey biomass from a mechanistic model, could provide useful predictions of pre-breeding arrival body mass of macaroni penguins (Eudyptes chrysolophus) from Marion Island, a standard metric of predator foraging success, measured over a 20-year period. In testing this, we used a spatially iterative correlation approach between predicted prey biomass and observed penguin arrival body mass, allowing likely foraging areas to emerge in regions most frequently associated with significant correlations. We then considered whether the distribution of these emergent foraging areas is consistent with tracking-derived foraging distributions for this species and island. Our results indicated emergent foraging areas where prey biomass was most often correlated with arrival body mass were located within expected and observed foraging ranges. Further, variability in prey biomass, within these emergent foraging areas provided reasonable predictions of annual penguin arrival body mass and outperformed metrics of primary production within these foraging areas. Our findings demonstrate that mechanistic models can provide biologically meaningful representations of difficult-to-observe prey, and can predict predator foraging success. This work could improve understanding of predator responses in a changing habitat. [ABSTRACT FROM AUTHOR]

Complete ophthalmic examinations were performed on 160 Macaroni penguins ( Eudyptes chrysolophus) and 90 Rockhopper penguins ( Eudyptes chrysocome) at eight North American zoological institutions. Cataract prevalence in the Macaroni population was 46.5% ( n = 74) of penguins and 42.3% (135/319) of eyes. Cataract prevalence in the Rockhopper population was 45.5% ( n = 40) of penguins and 40.6% (73/180) of eyes. The mean age of Macaroni penguins without ocular disease was 7.4 ± 5.8 yr, while that of Rockhoppers was 9.8 ± 6.4 yr. Risk factors for cataract were examined through husbandry surveys completed by each institution and by evaluation of light intensity and ultraviolet (UV) light measurements acquired in each penguin exhibit. Risk factors associated with cataract in Macaroni penguins included age, dietary smelt, hand-feeding, and fluorescent exhibit lighting. Risk factors associated with cataract in Rockhopper penguins included age, dietary capelin, increasing population density, and increasing length of minimum photoperiod. Factors associated with decreased odds of cataract in Macaroni penguins included saltwater pool, monitoring of water quality for salinity, pH, and alkalinity; use of water additives; presence of pool filtration and sterilization systems; use of metal halide lightbulbs; increasing light intensity; and UV spectrum lighting. Factors associated with decreased odds of cataract in Rockhoppers included dietary herring and krill, increasing exhibit land area, pool temperature monitoring, increasing maximum photoperiod, and increasing minimum UV light. [ABSTRACT FROM AUTHOR]

The South Sandwich Islands, in the South Atlantic Ocean, are a major biological hot spot for penguins and other seabirds, but their remoteness and challenging coastlines preclude regular biological censuses. Here we report on an extensive survey of the South Sandwich Islands, the first since the late 1990s, which was completed through a combination of direct counting, GPS mapping, and interpretation of high-resolution commercial satellite imagery. We find that the South Sandwich Islands host nearly half of the world's Chinstrap Penguin ( Pygoscelis antarctica) population (1.3 million breeding pairs), as well as c. 95,000 breeding pairs of Macaroni Penguins ( Eudyptes chrysolophus), and several thousand breeding pairs of Gentoo Penguins ( Pygoscelis papua). Despite being at the northern edge of their breeding range, we found an unexpectedly large (≥125,000 breeding pairs) population of Adélie Penguins ( Pygoscelis adeliae). Additionally, we report that nearly 1900 pairs of Southern Giant Petrels ( Macronectes giganteus) breed in the South Sandwich Islands, 4 % of the global population, almost all of which are found on Candlemas Island. We find that the South Sandwich Islands have not experienced the same changes in penguin abundance and distribution as the rest of the Scotia Arc and associated portions of the western Antarctic Peninsula. This discovery adds important context to the larger conversation regarding changes to penguin populations in the Southern Ocean. [ABSTRACT FROM AUTHOR]

Knowledge regarding interactions between predators and their prey is fundamental for understanding underlying links between climate change and ecosystem responses, including predator demographics, in the Southern Ocean. This study reports data on reproductive performance, total population size and diet composition for macaroni and chinstrap penguins breeding at Nyrøysa on Bouvetøya during the summers of 1996–97, 1998–99, 2000–01 and 2007–08. The breeding populations of these two species at Nyrøysa decreased significantly over the study period, with an 80% decline for chinstraps and a 50% decline for macaroni penguins, despite relatively high levels of chick production. During this period macaroni penguins at this site ate a diverse diet, dominated by myctophid fish and two krill species, whereas chinstrap penguins were Antarctic krill specialists. The population changes are probably primarily due to the expanding Antarctic fur seal population, and also to landslides that are the result of increased melting on the island which have destroyed penguin breeding sites. Additional impacts from global warming of the ocean might also be playing a role and could exacerbate the decline in these penguin populations if krill and other prey are negatively impacted in the future in this region. The local chinstrap penguin population would probably be most heavily affected given its narrow feeding niche and small current population size. [ABSTRACT FROM PUBLISHER]

Ophthalmic examinations were performed on 160 macaroni penguins ( Eudyptes chrysolophus) and 90 southern rockhopper penguins ( Eudyptes chrysocome) at eight North American zoos and aquaria. Intraocular pressure (IOP) was measured using rebound tonometry while penguins were held in two different body positions. Correlations between IOP and factors including age, body position, eye pathology, and housing parameters were evaluated. Normal macaroni penguins had a mean IOP of 42.0 ± 9.7 mm Hg. Normal rockhopper penguins had a mean IOP of 32.9 ± 6.2 mm Hg. Neither species had significantly different IOP between sexes or between left and right eyes of the same penguin. In both species, there was a negative linear correlation between age and IOP. In the macaroni population, IOP was significantly higher when IOP measurement was performed before ophthalmic exam; this was not true in rockhoppers. In both species, IOP measured in a horizontal body position was significantly higher than IOP measured in a vertical body position. In both species, eyes with corneal lesions had significantly lower IOP than normal eyes. In the macaroni penguin, eyes with rubeosis iridis had significantly lower IOP than normal eyes. In macaroni penguins, eyes with cataracts had significantly lower mean IOP than normal eyes; this was not true for rockhoppers. [ABSTRACT FROM AUTHOR]

Aim To infer the potential for competition between an important Antarctic predator, the macaroni penguin, and the krill fishery by examining the spatial overlap in prey consumption and catches. Location Scotia Sea and adjacent waters. Methods The study focused on the winter period as this is the only time of the year when spatio-temporal overlaps between macaroni penguin foraging and the krill fishery can occur. We tracked adult macaroni penguins from a colony in South Georgia using global location sensors to determine winter distribution, and bioenergetics models to calculate the biomass of food consumed during the winter period. We combined these to produce a surface of the tonnes of krill consumed, which could be compared directly with the spatial distribution of the tonnes of krill caught by the fishery. Results Adult macaroni penguins from South Georgia consumed 135,826 tonnes of krill (95% CIs: 83,446-188,140) during the winter, which is similar to the 98,431 tonnes caught by fisheries over the same period. However, macaroni penguins had a very wide pelagic distribution across the Scotia Sea, whereas the fishery was restricted to three small areas on shelf edges, such that their spatial overlap was negligible. The proportion of the estimated krill stock taken by macaroni penguins and the krill fishery was small at both the scale of the Scotia Sea and the local areas within which the fisheries operate. Main conclusions Competition between macaroni penguins and the krill fishery is low under current management and far less than that among the various species of krill predators that occur in the Scotia Sea. Our method will allow quantification of changes in competition between macaroni penguins and krill fisheries should the latter expand in the future, and provides a framework for assessing predator-fishery competition in other systems. [ABSTRACT FROM AUTHOR]

A 25-year-old female macaroni penguin ( Eudyptes chrysolophus) was diagnosed with exophthalmos secondary to retrobulbar neoplasia through use of computed tomography (CT). Histopathologic examination of the mass supported a diagnosis of malignant round cell neoplasia. Immunohistochemical (IHC) labeling was applied to determine cell origin; the neoplastic cells did not label with T-cell marker CD3 or B-cell marker BLA.36 and could not be further characterized. The scleral ossicles precluded evaluation of the retrobulbar space by ultrasonography; therefore, CT scanning is recommended for examination of intraorbital structures in penguin and other avian species. [ABSTRACT FROM AUTHOR]

Objective To describe ophthalmic examination findings and standard diagnostic test results in 2 penguin species. Animals Studied Macaroni & Southern Rockhopper Penguins. Procedure Complete ophthalmic examinations including Schirmer tear test ( STT), modified phenol red thread test ( PTT), tonometry, and echobiometry were performed on penguins housed at the Detroit Zoo. Mean and standard deviation of ophthalmic tests are reported and compared for significance using two sample t-tests with significance set at P < 0.05. Correlations between variables were assessed using Pearson's correlation coefficient. Results Cataracts were the most common finding, present in 64% of Macaroni Penguins, and 68% of Rockhopper Penguins. There were anterior segment anomalies in all eyes with cataracts consistent with lens-induced uveitis. The mean modified PTT for the Macaronis was 24.7 ± 6.37 mm/15 s and 25.1 ± 7.07 mm/15 s in the Rockhoppers. The mean STT value for the Macaronis was 12.1 ± 5.43 mm/min and 11.0 ± 3.96 mm/min in the Rockhoppers. Mean intraocular pressure ( IOP) for the Macaronis was 21.9 ± 7.05 mmHg measured by applanation tonometry and 29.1 ± 7.16 mmHg using rebound tonometry. The Rockhoppers had a mean IOP of 20.0 ± 5.77 mmHg and 24.1 ± 5.09 mmHg for applanation and rebound tonometry, respectively. In both populations, there was a significant difference in IOP measurement between the two instruments. In the Macaroni penguins, the presence of cataracts correlated significantly with increased age and lower IOP readings. Anterior chamber distance and axial globe length were significantly greater in males than in females in both penguin species. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim Competition for food among populations of closely related species and conspecifics that occur in both sympatry and parapatry can be reduced by interspecific and intraspecific spatial segregation. According to predictions of niche partitioning, segregation is expected to occur at habitat boundaries among congeners and within habitats among conspecifics, while negative relationships in the density of species or populations will occur in areas of overlap. We tested these predictions by modelling the winter distributions of two crested penguin species from three colonies in the south-western Atlantic. Location Penguins were tracked from two large colonies on the Falkland Islands and one in South Georgia, from where they dispersed through the South Atlantic, Southern Ocean and south-eastern Pacific. Methods Forty macaroni penguins ( Eudyptes chrysolophus) from South Georgia and 82 southern rockhopper penguins ( Eudyptes chrysocome chrysocome) from two colonies in the Falkland Islands were equipped with global location sensors which log time and light, allowing positions to be estimated twice-daily, from April to August in 2011. Positions were gridded and converted into maps of penguin density. Metrics of overlap were calculated and density was related to remote-sensed oceanographic variables and competitor density using generalized additive models. Results Macaroni penguins from western South Georgia and southern rockhopper penguins from Steeple Jason Island, Falkland Islands, were spatially segregated by differences in their habitat preferences thus supporting our first prediction regarding interspecific segregation. However, southern rockhopper penguins from Beauchêne Island showed a marked spatial overlap with macaroni penguins as the two had similar habitat preferences and strong mutual associations when controlling for habitat. Contrary to our predictions relating to intraspecific segregation, southern rockhopper penguins from Beauchêne Island and Steeple Jason Island were segregated by differences in habitat selection. Main conclusions Morphological differentiation probably allows macaroni penguins from South Georgia and southern rockhopper penguins from Beauchêne Island to coexist in areas of spatial overlap, whereas segregation of the two Falkland rockhopper penguin populations may have arisen from two distinct lineages retaining cultural fidelity to ancestral wintering areas. [ABSTRACT FROM AUTHOR]

Due to their restricted foraging range, flightless seabirds are ideal models to study the short-term variability in foraging success in response to environmentally driven food availability. Wind can be a driver of upwelling and food abundance in marine ecosystems such as the Southern Ocean, where wind regime changes due to global warming may have important ecological consequences. Southern rockhopper penguins (Eudyptes chrysocome) have undergone a dramatic population decline in the past decades, potentially due to changing environmental conditions. We used a weighbridge system to record daily foraging mass gain (the difference in mean mass of adults leaving the colony in the morning and returning to the colony in the evening) of adult penguins during the chick rearing in two breeding seasons. We related the day-to-day variability in foraging mass gain to ocean wind conditions (wind direction and wind speed) and tested for a relationship between wind speed and sea surface temperature anomaly (SSTA). Foraging mass gain was highly variable among days, but did not differ between breeding seasons, chick rearing stages (guard and crèche) and sexes. It was strongly correlated between males and females, indicating synchronous changes among days. There was a significant interaction of wind direction and wind speed on daily foraging mass gain. Foraging mass gain was highest under moderate to strong winds from westerly directions and under weak winds from easterly directions, while decreasing under stronger easterly winds and storm conditions. Ocean wind speed showed a negative correlation with daily SSTA, suggesting that winds particularly from westerly directions might enhance upwelling and consequently the prey availability in the penguins' foraging areas. Our data emphasize the importance of small-scale, wind-induced patterns in prey availability on foraging success, a widely neglected aspect in seabird foraging studies, which might become more important with increasing changes in climatic variability. [ABSTRACT FROM AUTHOR]

Macaroni penguins Eudyptes chrysolophus are thought to be one of the most important mesopredators in the Southern Ocean having a greater impact on prey availability and abundance than any other seabird species. Their population centre has long been held to be South Georgia where populations were thought to comprise many million animals. Here we report the results of a recent census of the macaroni population at South Georgia undertaken using aerial survey methods. We report dramatic declines in numbers (∼1.0 million breeding pairs) compared to numbers observed in the late 1970s (∼5.4 million pairs), but show that these reductions have occurred principally at sites where numbers had previously been very large. During the breeding season, the main foraging grounds of birds from these sites overlap with the foraging grounds of Antarctic fur seals Arctocephalus gazella, a major competitor for their principal prey, Antarctic krill Euphausia superba. We suggest that the redistribution of the macaroni penguin population at South Georgia reflects the recent recovery of fur seal populations and thus the ongoing consequences of human intervention at South Georgia, a process which started more than 2 centuries previously. The implied resource competition and the observed population changes may also be exacerbated by recent reductions in Antarctic krill abundance which have been linked with reductions in seasonal sea ice following recent, rapid, regional warming in the Antarctic; however, the recovery of fur seal populations, and the ongoing recovery of krill-eating whale populations argues that tropho-dynamic interactions may be sufficient to explain the observed changes. [ABSTRACT FROM AUTHOR]

The article discusses sighting of an apparent immature Royal Penguin Eudyptes Schlegeli on New Island, Falkland Islands. The white-faced bird sighted on New Island had comparatively short crest feathers, suggesting it was not yet a fully grown adult. Based on its overall size and its long and high build, it is suggested that the bird was a male. The observed sizes differences and stronger likelihood that a pale-faced individual is a Royal Penguin argue against the possibility that it was an aberrant Macaroni Penguin.

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. [ABSTRACT FROM AUTHOR]

The article features South Georgia, a mountainous island in the waters of the Southern Ocean, a British Oversees Territory, and an important seabird island. More than 100 million seabirds are estimated to be based in the island, with 29 species of breeding bird, and is considered the most important breeding site in the world for six species including Macaroni Penguin Eudyptes chrysolophus, Grey-headed Albatross Thalassarche chrysostoma, and Northern Giant Petrel Macronectes halli.

It has long been held that Eudyptes penguins will only ever develop a maximum of two mature yolky follicles to match their invariant two-egg clutch, an idea inferred largely from egg removal studies. Combining our own data with those from a previous but rarely cited study and by applying these to a simple developmental model, we show that macaroni penguins ( Eudyptes chrysolophus) develop up to four large, yolky vitellogenic follicles, and they do so despite the fact that they will never lay more than two eggs or rear more than one chick, a tactic that seems maladaptive given their realized reproductive success. We discuss these results within the context of the usual pattern of reproductive investment in Eudyptes penguins and suggest a broader significance to modes of clutch size determination among all penguins (order Sphenisciformes). [ABSTRACT FROM AUTHOR]

Predation by fur seals and sea lions has been identified, among others, as a potential cause of the declines in rockhopper penguin populations. Here, we report a multiple predation event of southern rockhopper penguins Eudyptes chrysocome by South American sub-adult male sea lions Otaria flavescens at Staten Island, Argentina. The sea lions attacked and preyed on penguins mostly using a wait and rush tactic at sea, but in some cases, penguins were also pursued on land. Although observations suggested that only a few sea lions are involved in predation, further research is necessary to elucidate the importance of this predation in the rate of population decline. [ABSTRACT FROM AUTHOR]

Hatching asynchrony in avian species generally leads to a size hierarchy among siblings, favouring the first-hatched chicks. Maternally deposited hormones affect the embryo and chick's physiology and behaviour. It has been observed that progesterone, a hormone present at higher levels than other steroid hormones in egg yolks, is negatively related to body mass in embryos, chicks and adults. A differential within-clutch progesterone deposition could therefore be linked to the size hierarchy between siblings and to the resulting brood reduction. We tested whether yolk progesterone levels differed between eggs according to future parental ability to feed the entire clutch in wild rockhopper penguins Eudyptes chrysocome. This species presents a unique reversed egg-size dimorphism and hatching asynchrony, with the larger secondlaid egg (B-egg) hatching before the smaller first-laid egg (A-egg). Yolk progesterone levels increased only slightly with female body mass at laying. However, intra-clutch ratios were not related to female body mass. On the other hand, yolk progesterone levels increased significantly with the date of laying onset for A-eggs while they decreased for B-eggs. Early clutches therefore had proportionally more progesterone in the B-egg compared to the A-egg while late clutches had proportionally less progesterone in the B-egg. We propose that females could strategically regulate yolk progesterone deposition within clutches according to the expected food availability during chick growth, an adaptive strategy to adjust brood reduction to conditions. We also discuss these results, relating to yolk progesterone, in the broader context of other yolk steroids. [ABSTRACT FROM AUTHOR]

Despite the large biomass of macaroni penguins Eudyptes chrysolophus in the Southern Ocean, their feeding ecology is poorly known at some important breeding localities. We investigated the diving behaviour and diet of female macaroni penguins feeding small chicks on Marion Island (46º52′S, 37º5′E), South Africa, one of the species' most northerly breeding sites, supporting 4% of their global population. We then compared our results with similar studies from other localities. In December 2008, we collected information on 12 foraging trips from 6 individuals using time-depth recorders, as well as diet from 42 individuals. Median trip duration was 22.8 h (5.6-80.8 h). Penguins performed 42.8 ± 15.9 dives per hour at sea, with dive depths averaging 24.6 ± 8.6 m and lasting 40.8 ± 12.1 s, although 74.3% of dives were <10 m. Euphasids dominated their diet (86% by mass), mainly Thysanoessa vicina. A second peak in dive depths at 55-80 m might reflect the 12% of fish in their diet. The substantial proportion of shallow night dives (30% of total dives) suggests some foraging occurs at night. Differences in diving patterns of individual macaroni penguins in this study confirmed the behavioural flexibility of these birds reported from other breeding localities. However, most other studies assumed that dives <3-5 m were commuting dives whereas our study suggests that at least some prey are caught during shallow dives. We highlight how different analytical methods can change the outcome of studies. Despite macaroni penguins' apparent flexibility in foraging behaviour during the breeding season, their numbers are decreasing globally. Further investigations of their foraging behaviour are needed to assess potential competition with other predators and krill fisheries. [ABSTRACT FROM AUTHOR]

The article discusses a research study on macaroni penguins, their distribution at sea during winter and trophic ecology variation in several colonies compared to neighbouring localities. Observed were 30 penguins from Kerguelen and Crozet Islands in the Indian Ocean from 2006-2007 through the stable isotope analyses for trophic ecology and their habitat use with miniatrurised light-based geolocators. Results indicated large distribution patterns of macaroni penguins in Polar Frontal Zone deep oceanic waters with temperatures ranging from 3.0 to 3.5 degrees Centigrade. Additional findings include the distribution of those from Crozet in distinct areas far from the Kerguelen birds while their trophic ecology remain similar.

Abstract: In altricial and semi-altricial species, asynchronous hatching gives the first chicks to hatch an initial advantage over other siblings and often leads to the elimination of the smallest chicks. Both baseline corticosterone and acute stress-induced corticosterone levels have been shown to be higher in food deprived chicks than in chicks fed ad libitum. However, first-hatched chicks have also been shown to exhibit higher corticosterone levels than last-hatched chicks, suggesting an influence of the initial differences between eggs on corticosterone levels. We subjected single-chicks of southern rockhopper penguins Eudyptes chrysocome chrysocome to a standardised capture-stress protocol. In this species having very dimorphic two-egg clutches, we examined whether corticosterone levels were different between the two chick categories and tested for the effect of body condition controlled by the chick category. Neither body sizes, nor corticosterone levels differed between A- and B-chicks at 18days. In contrast to baseline corticosterone levels, acute stress-induced levels of corticosterone were negatively correlated to body condition: chicks with a good body condition had lower acute stress-induced levels of corticosterone than chicks with a poor condition, whatever the chick category. Our results do not support the idea that initial differences in egg characteristics could drive the difference in corticosterone levels between siblings. On the contrary, they show that the A-egg of rockhopper penguins has, when reared alone, the same intrinsic potential to develop into a fledged chick as the B-egg. Later differences in body condition appear to lead to variation in the acute stress-induced levels of corticosterone. [ABSTRACT FROM AUTHOR]

Where life-history stages overlap, there is the potential for physiological conflicts that might be important in mediating carryover effects. However, our knowledge of the specific physiological mechanisms underlying carryover effects remains rudimentary, and specific examples remain rare. Here we show that female macaroni penguins (Eudyptes clirysolophus) initiate vitellogenesis and yolk formation while at sea during return migrations to breeding colonies; yolk formation takes approximately 16 days, but females lay only 714 days after their return. Once on land, Eudyptes penguins show a unique reproductive pattern of extreme egg size dimorphism in which the smaller, first-laid A-egg is 55%-75% of the size of the larger B-egg. We show that the degree of egg size dimorphism is inversely correlated with time between arrival and laying; that is, females that begin reproductive development well in advance of their return produce more dimorphic eggs. Furthermore, late-arriving females that produce the most dimorphic eggs have lower plasma levels of the yolk precursor vitellogenin on arrival; that is, they show lower reproductive "readiness." These data support the hypothesis that extreme egg size dimorphism in Eudyptes penguins is due to a physiological constraint imposed by a migratory carryover effect and argue against small A-eggs having a specific, adaptive function. [ABSTRACT FROM AUTHOR]

On 20 and 22 January 2007, we observed macaroni penguins ( Eudyptes chrysolophus) on Avian Island, Antarctica, approximately 1° south of the Antarctic Circle along the Western Antarctic Peninsula (WAP) near Adelaide Island, a new high-latitude observational record for the species within this region of the continent. Additionally, we report several extra-limital sightings of macaroni penguins over the last decade at relatively lower latitudes along the WAP near Anvers Island, including observations of breeding attempts. Although vagrancy cannot be ruled out as a possible causal factor in our observations, we hypothesize that a climate-induced shift in the species’ bio-geographic range may be in progress. In this context, our observations are similar to the well-documented range shifts and eventual establishment of breeding populations by other sub-Antarctic penguin species along the WAP, over the last three decades, in response to regional climate warming. We highlight that the few observations reported here do not provide conclusive evidence for any putative causal mechanism explaining the presence of macaroni penguins at locations outside their natural geographic range. However, our observations are important for developing a better understanding of the natural history of the species along the WAP. [ABSTRACT FROM AUTHOR]

Recording the activity of animals as they migrate or forage has proven hugely advantageous to understanding how animals use their environment. Where animals cannot be directly observed, the problem remains of how to identify distinct behaviours that represent an animal’s decision-making process. An excellent example of this problem is that of foraging penguins, which travel to sea to find prey to provision their young. Without direct sampling of the prey field, we cannot calibrate patterns of movement with prey capture, and therefore we cannot determine how different activities link to decision-making. To overcome this, we use a hidden markov model (HMM), which is a machine-learning technique that seeks to identify the underlying states of a system from observable outputs. We apply HMM to determine classes of behaviour from repetitive dives. We take dive data from 103 breeding macaroni penguins at Bird Island, South Georgia, for which we have measures of weight gain over a trip. We identify two classes of behaviour; those of short-shallow and long-deep dives. Using these two behaviours, we calculate the transition probabilities between these states and analyse these data to determine what predicts variation in the transition probabilities. We found that the stage of reproduction during a season, the sex and year of an individual influenced the probability of transition between long-deep and short-shallow sequential dives. We also found differences in the hourly transition rates between the four reproductive stages (incubation, broodguard, crèche and premoult) over a daily cycle. We conclude that this application of HMMs for behavioural switching is potentially useful for other species and other types of recorded behaviour. [ABSTRACT FROM AUTHOR]

The nature of how behaviour at one time step influences the next is of great interest to behavioural ecologists, but rarely used for comparisons between animals. Time depth recorders (TDR) and other archival tags have been widely used to infer patterns of diving and foraging. However, while we can extract variables that describe individual dives, how runs of dives may indicate behaviours and how one dive influences the next are not fully understood. Treating TDR data as time series, we examined patterns of autocorrelation to investigate structure in the timing of behaviour. We fitted an oscillating best-fit curve to the autocorrelation and used the parameters of this curve to investigate differences in foraging strategy of 129 macaroni penguins, Eudyptes chrysolophus, of both sexes. We found interannual differences in autocorrelation parameters as well as differences between reproductive stages. In contrast to other studies of macaroni penguin diving based on depth analysis, we found no differences between the sexes. We mimicked changes in the various parameters by simulation of dive profiles, and used these to infer biological meaning from the parameters. As this technique makes very few assumptions about how to identify a dive or cluster of dives, we suggest that it is a useful first characterization of diving or cyclical behaviour in a wide range of animals. [Copyright &y& Elsevier]

Antarctic fur seals Arctocephalus gazella and macaroni penguins Eudyptes chrysolophus are the two main land-based krill Euphausia superba consumers in the northern Scotia Sea. Using a combination of concurrent at-sea (predator observations, net hauls and multi-frequency acoustics), and land-based (animal tracking and diet analysis) techniques, we examined variability in the foraging ecology of these sympatric top predators during the austral summer and autumn of 2004. Krill availability derived from acoustic surveys was low during summer, increasing in autumn. During the breeding season, krill occurred in 80% of fur seal diet samples, with fish remains in 37% of samples. Penguin diets contained the highest proportion of fish in over 20 years of routine monitoring (46% by mass; particularly the myctophid Electrona antarctica), with krill (33%) and amphipods ( Themisto gaudichaudii; 21%) also occurring. When constrained by the need to return and feed their offspring both predator species foraged to the northwest of South Georgia, consistent with an area of high macrozooplankton biomass, but fur seals were apparently more successful at exploiting krill. When unconstrained by chick-rearing (during March) penguins foraged close to the Shag Rocks shelf-break, probably exploiting the high daytime biomass of fish in this area. Penguins and seals are able to respond differently to periods of reduced krill abundance (in terms of variability in diet and foraging behaviour), without detriment to the breeding success of either species. This highlights the importance of myctophid fish as an alternative trophic pathway for land-based predators in the Scotia Sea ecosystem. [ABSTRACT FROM AUTHOR]

Four species of penguin breed regularly at South Africa's Prince Edward Islands: king penguin Aptenodytes patagonicus, gentoo penguin Pygoscelis papua, macaroni penguin Eudyptes chrysolophus and southern rockhopper penguin E. chrysocome. In December 2008, it was estimated that some 65 000 pairs of king penguins were incubating eggs at Marion Island, the larger of the two islands in the group, and 2 000 pairs at Prince Edward Island. At Marion Island from 1987 to 2008, there was no long-term trend in numbers of king penguin chicks that survived to the end of the winter period, but there was considerable fluctuation in chick production in the 1990s. It was roughly estimated that on average 88% of king penguin chicks survived the winter period (from April to September/October). Numbers of gentoo penguins at Marion Island decreased from more than 1 300 pairs in the mid-1990s to fewer than 800 pairs in 2003, and then increased to almost 1 100 pairs in 2008 as breeding success improved. Between 1994/1995 and 2008/2009, numbers of macaroni and southern rockhopper penguins at Marion Island decreased by about 30% and 70% respectively. In 2008/2009, some 290 000 pairs of macaroni penguins bred at this island, mostly in two large colonies where there was a progressive decrease in the density of nests. At both these colonies, decreases in numbers breeding followed outbreaks of disease. Inadequate breeding success has influenced the decreases of macaroni and rockhopper penguins. In 2008/2009, some 42 000 pairs of southern rockhopper penguins bred at Marion Island and 12 000 pairs of macaroni penguins and 38 000 pairs of southern rockhopper penguins at Prince Edward Island. [ABSTRACT FROM AUTHOR]

We report the characterization of 25 microsatellite loci isolated from the macaroni penguin ( Eudyptes chrysolophus). Thirteen loci were arranged into four multiplex sets for future genetic studies of macaroni penguin populations. All 25 loci were tested separately in each of four other penguin species [Adélie penguin ( Pygoscelis adeliae), chinstrap penguin ( Pygoscelis antarctica), gentoo penguin ( Pygoscelis papua) and king penguin ( Aptenodytes patagonicus)]. Between eight and 12 loci were polymorphic per species. These loci are expected to be useful for studies of population genetic structure in a range of penguin species. [ABSTRACT FROM AUTHOR]

The article reports on avian disease outbreaks at sub-Antarctic Marion Island, one of South Africa's Prince Edward Islands in the south-west Indian Ocean, and considers what procedures should be adopted to reduce the risks of further outbreaks at the island group. Several species of King Penguins Aptenodytes patagonicus and an estimated 5-10 thousand Macaroni Penguins Eudyptes chrysolophus were reportedly killed by unknown diseases in the island during 1992 and 1993. An outbreak of avian cholera Pasteurella multocida was also reported in the same island during November 2004. Procedures for preventing these outbreaks have been developed in the islands and in Antarctica.

We measured daily energy expenditure (DEE) continuously for a whole year in a free ranging bird, the macaroni penguin Eudyptes chrysolophus. We combined these measurements with concurrently recorded foraging behaviour, and literature information on body mass and dietary factors to estimate prey consumption rates and foraging success. DEE was at a maximum during late chick-rearing but was equally high during all other active phases of the breeding season. DEE was approximately 4×resting metabolic rate, which accords with established theory and suggests a common ‘energetic ceiling’ throughout the summer period. However, whether this represents a maximum in physiological capacity, or a rate which optimises fitness is still unclear. Rates of prey consumption and foraging success followed different patterns from daily energy expenditure. Daily prey consumption was high as the penguins prepared for long fasts associated with moulting and incubation but relatively low during chick-rearing, when foraging areas were restricted and foraging success lower. It appears that the energy intake of macaroni penguins is subject to extrinisic or environmental constraints rather than to intrinsic physiological limits. [ABSTRACT FROM AUTHOR]

The article discusses research on the at-sea movements of the macaroni penguin Eudyptes chrysolophus during its inter-breeding period at Kerguelen Islands. The study utilized global location sensors (GLS) attached to the penguins in order to monitor their foraging movements and feeding habits during winter. It has observed varying monthly traveling speed in the penguins during the season. Other findings include similar migratory behaviour in all the penguins and unexpected dispersal over winter.

Abstract: Female birds deposit corticosterone into their eggs. Elevated concentrations of this hormone may interfere with the development of their offspring, and mothers should thus regulate corticosterone levels deposited into the eggs adaptively. However, if females are unable to regulate deposition, then the corticosterone concentration in eggs should reflect that in female plasma and should be influenced by stressors to the females. We measured corticosterone levels in the albumen of rockhopper penguins, and assessed their relationship with hatching order, human disturbance and laying date. Rockhopper penguins (Eudyptes chrysocome chrysocome) lay two eggs, of which the second egg (B-egg) is larger and hatches faster than the first egg (A-egg). The chick hatching from the B-egg is also much more likely to survive than its sibling. Albumen corticosterone concentrations were lower in B-eggs. However, as B-eggs contained more albumen than A-eggs, the total corticosterone deposited in the albumen was not significantly different between the two eggs. Daily disturbance by human observers during albumen production did not influence albumen corticosterone levels. Laying date had an effect on total albumen corticosterone through a higher albumen mass. However, we observed a high individual component in the composition of eggs from the same clutch. Thus, more work is required to explore the hypotheses of passive versus active transfer to eggs and to understand the adaptive value of contrary effects on the amount and concentration of corticosterone. [Copyright &y& Elsevier]

Abstract: High corticosterone levels can have deleterious effects in developing avian embryos and chicks. Therefore, it may be adaptive for avian mothers to reduce corticosterone transfer to their eggs. However, until now, data about the active or/and passive role of mothers in corticosterone transfer to eggs are inconclusive. Here, we study maternal investment into A- and B-eggs of southern rockhopper penguins (Eudyptes chrysocome chrysocome). This species exhibits reversed hatching asynchrony and provides a unique model to test whether there is a strategic investment in corticosterone favoring the B-chick, which is most likely to survive. We found that rockhopper penguins had the highest yolk concentrations of any wild bird species studied so far. Contrary to our expectations, B-eggs had more yolk corticosterone both in concentration and in quantity than A-eggs, independently of the laying period and the level of human disturbance. Additionally, females deposited more yolk corticosterone in their eggs when they were disturbed. However, this disturbance effect was particularly strong for A-eggs and for late-laid eggs. The present data support neither the predictions for an active regulation nor for a passive deposition, and hormone deposition mechanisms still need to be explored. The adaptive value, if any, of high yolk corticosterone is presently unknown. [Copyright &y& Elsevier]

The diving behaviour of female southern rockhopper penguins ( Eudyptes chrysocome) was studied at Noir Island (54°30′S–73°00′W), Chile, in the southeast Pacific Ocean. This isolated island is located at the edge of the continental shelf in an area where the Humboldt Current originates, and holds a population of more than 150,000 breeding pairs. On 13 December 2005, four TDRs were successfully attached to females at the end of the brooding period and recorded diving activity at intervals of 2 s over the next 4 weeks. In total, 40 complete foraging trips were recorded. Trip duration was on average 42.4 ± 40.1 h and the proportion of overnight trips (60%) was the highest value found so far for this species. Mean dive depth and dive duration was 20.6 ± 19.4 m and 63.7 ± 36.4 s, respectively. The diving effort was higher than that of brooding females from the Indian Ocean and comparable with that of conspecifics from colonies in the southwest Atlantic in terms of diving rate (38 ± 14.2 dives h−1), but slightly lower as regards the proportion of time spent underwater (61 ± 10.5%). This study confirms that the diving behaviour of rockhopper penguins varies as a function of the physical and biological characteristics of the foraging areas and of the particular stage of the breeding season. [ABSTRACT FROM AUTHOR]

The movement of marine vertebrates has been tracked using a variety of techniques, all of which depend on the external attachment of a transmitting or recording device. However, these devices can have negative effects on the subject animals, limiting both the quantity and quality of data collected. We present a new method for monitoring large-scale movement of marine vertebrates that uses behavioural data stored on a surgically implanted data logger. The technique (‘behavioural geolocation’) relies on the principles of light-based geolocation but rather than measuring ambient light levels, changes in diving behaviour associated with sunrise and sunset are used to infer daylength and time of local sunrise, and hence location. We present data from a trial, post-hoc, analysis of diving data collected from macaroni penguins Eudyptes chrysolophus during long foraging trips associated with incubation and preparation for moult. Our results showed that the penguins usually travelled to the polar frontal zone to the north of their breeding colony at South Georgia, an area broadly consistent with previously measured behaviour and the availability of preferred prey at this period of the annual cycle. [ABSTRACT FROM AUTHOR]

We surveyed the coast of Chile between Isla Terhalten (54° 20' S) and Islote Leonard (55° 44' S) by boat during November-December 2005 to document breeding locations of Rockhopper (Eudyptes chrysocome chrysocome) and Macaroni (E. chrysolophus) penguins, and to count the number of nests during the early incubation period. A yacht-based observation recorded 1,000 Rockhopper Penguin nests at Isla Terhalten. Ground-based counts at Isla Noir estimated a total of 158,200 Rockhopper and 3,470 Macaroni penguin nests in 17 mixed colonies and one Macaroni Penguin breeding colony. The Rockhopper population on Isla Noir increased significantly from the previous estimate of 70,000 pairs, making this island the most important breeding site for the southern subspecies of Rockhopper Penguin. The new estimate for Rockhopper Penguins suggests a population increase over the last 20 years, consistent with recent data for the main colony in Argentina. Conservation status of the species and the factors potentially responsible for population declines elsewhere may need to be re-evaluated. [ABSTRACT FROM AUTHOR]

The rockhopper penguins Eudyptes chrysocome have recently been split into the northern E. moseleyi and the southern E. chrysocome rockhopper penguin. It is therefore crucial to have a comprehensive understanding of the biology of each species in order to develop appropriate conservation measures. We investigated the breeding biology of the southern rockhopper on New Island, in the western part of the Falklands Islands, by following the breeding attempt of 160 pairs during the 2006/2007 season and examining the effect of lay time and colony habitat on breeding success. Specifically, we compared survival and growth parameters between A- and B-eggs and chicks from non-manipulated and artificially manipulated nests to investigate why southern rockhopper penguins in the Falkland Islands are more able to fledge an A-egg (first laid) than conspecifics elsewhere. Breeding was highly synchronous, with no significant difference in the breeding success between early and late breeders or between pairs breeding in different habitats. We demonstrate for the first time that the A-egg produced by the southern rockhopper penguin has, when alone, the same theoretical intrinsic potential to lead to a fledged chick as the B-egg. In contrast, the hatching success and survival of the B-chick was similar when alone or in a two-egg clutch. [ABSTRACT FROM AUTHOR]

For rockhopper penguins Eudyptes chrysocome at Marion Island, there were significant decreases over time in the numbers breeding and breeding success at three monitored colonies from 1985/1986 to 2006/2007, and in mass on arrival for breeding of both males and females from 1994/1995 to 2007/2008. Breeding success decreased by 0.15 chicks pair-1 y-1 over 22 years and was significantly correlated with mass on arrival of males and females. Survival of chicks at the guard stage was low in the late 1990s; hatching success decreased in the early 2000s. It is thought that an increasingly poor parental condition caused birds to abandon breeding at a progressively early stage. Parental condition is influenced by feeding opportunities at overwintering grounds, which have probably been altered by global climate. [ABSTRACT FROM AUTHOR]