Penguin Populations Research Articles

Diet plasticity and links to changing foraging behaviour in the conservation of subantarctic yellow‐eyed penguins (Megadyptes antipodes)

Abstract Diet is a key factor affecting seabird foraging behaviour, ultimately influencing survival, breeding success and long‐term population viability. The density and distribution of prey species in the marine environment are influenced by many factors including climate effects such as El Niño southern oscillation and climate change that alter water temperature. While poor quality diet has been implicated as a contributing factor in the decline of some mainland New Zealand yellow‐eyed penguin (Megadyptes antipodes) populations, little is known about their diet in the subantarctic where the majority of the species breeds. Blood and feather samples (n = 63) were collected for stable isotope analysis of diet from 25 individual birds breeding on subantarctic Enderby Island, Auckland Islands, New Zealand, from 2015 to 2018. Diet data were analysed by factors such as breeding year, sex and foraging behaviour. Stable isotope analysis demonstrated significant changes in diet during each year of the study, which included both El Niño and La Niña conditions. Diet during El Niño conditions comprised lower trophic level prey, which were more benthic, and found closer to shore than diet during La Niña. Coupled with the reported variable breeding success of yellow‐eyed penguins in the subantarctic, variable diet suggests prey availability is likely to be a limiting factor in some years. Prey availability is therefore expected to be a major influence on survival and breeding success of this endangered species in the future, particularly if the effects of climate change become more pronounced. This research highlights an urgent conservation need to identify prey species utilized by the southern population, along with their distribution in time and space, and therefore also the effect of diet on long‐term population stability.

Status of breeding birds at Observatorio and Goffré Islands, Argentina

Continental islands are often sites of low diversity and endemism, as well as important areas for the protection of bird populations, especially seabirds. On Isla Observatorio and the Año Nuevo Islands, in the Southwestern Atlantic, the latest assessment of avifauna dates from more than 20 years ago. In this study, we use a combination of methods to update the status of the main seabird colonies and the most abundant avian terrestrial predator at Observatorio and Goffré Islands during the breeding season. In only 4.5 km2, the islands would harbour ~ 90,000 breeding seabirds. Seabird colonies occupied different areas of the islands and varied in their population status, with Imperial Shags (Leucocarbo atriceps) showing an increase and Southern Giant Petrels (Macronectes giganteus) a decrease according to the last surveys. Magellanic Penguin (Spheniscus magellanicus) population estimations also suggest a decrease but the last survey was based on total, and not on occupied nest sites. We recorded and assessed one new breeding species: The globally near-threatened Striated Caracara (Phalcoboenus australis), which has an important breeding population of around 15 territorial pairs at Observatorio Island. These islands appear to be an important regional bird site and future studies would determine their trends and threats, especially those related with invasive species.

Ornithogenic soils in the lake margin reveal the most recent Adélie penguin recolonization in Cape Royds, Antarctica

Ice-free areas hold the most biologically active and diverse ecosystems in Antarctica, in which penguins play an important role. As the climate conditions changed in the past, penguins migrated among different breeding sites, making their populations recorded in a certain area a key index to explore the interactions between the local environment and ecological processes. Two 210Pb-dated ornithogenic soil profiles encoded MR1 and MR2 are used in this study to recover the time of Adélie penguin (Pygoscelis adeliae) recolonization in Cape Royds of Ross Island, and their recent population change based on the element assemblage related to penguin guano, including Cu, Cd, Hg, P, S, Se, and Zn. It is revealed by both profiles that abundant penguins reentered this ice-free area at about 1820 to 1830, corresponding to the onset of a continuous warming. We found the reconstructed penguin population change pattern of MR1 in the lake margin in good agreement with the census and monitoring data since the late 1950s, and the pattern was subjected to environmental factors including temperature, sea ice, and polynyas. Our results showed that the ornithogenic soils in the lake margin can reflect the size of the penguin colony, and bridge the gap between long-term records and modern census, laying the basis for assessing the future penguin population in response to the drastically changing climate due to anthropogenic influence.

Optimization of semen cryopreservation in black-footed (Spheniscus demersus) and gentoo (Pygoscelis papua) penguins using dimethylacetamide and dimethylsulfoxide

Black-footed penguins (Spheniscus demersus) are classified as endangered, and the populations of gentoo penguins (Pygoscelis papua) are rapidly decreasing. The optimization of semen cryopreservation in these species, for preserving their genetic diversity in genome resource banks, is essential for the success of captive breeding programs. This study compares the effectiveness of two permeating cryoprotectants, dimethylacetamide (DMA) and dimethylsulfoxide (DMSO), on frozen–thawed sperm characteristics. Semen samples were collected during each breeding season once a week during two consecutive years. Semen samples were packaged in 0.25 ml straws and frozen by placing them in nitrogen vapors. After thawing, sperm motility characteristics were examined by computer-assisted sperm analysis. Propidium iodide and SYBR-14 were used as fluorochromes for the examination of membrane integrity. DNA integrity was evaluated by TUNEL assay. Gentoo sperm characteristics after freeze-thawing did not show any differences when using DMSO or DMA. In black-footed samples, progressive motility, curvilinear velocity (VCL), straight-line velocity (VSL), average path velocity (VAP), linearity (LIN), and straightness (STR) were greater using 8% DMSO (P < 0.05) than 6% DMA. The cryoresistance ratio (CR) using 8% DMSO was greater (P < 0.05) in gentoo than black-footed samples for CR-VCL and CR-VAP, and 6% DMA returned greater CR values (P < 0.05) than in black-footed samples for all characteristics evaluated. No differences were found in DNA fragmentation. In conclusion, the present results highlight the benefits of using 8% DMSO compared to 6% DMA in penguins. Sperm from black-footed showed a higher sensitivity to freezing-thawing process than gentoo sperm.

Blood biochemistry and antioxidant status altered by anthropogenic impact in Adélie penguins (Pygoscelis adeliae).

Human activities are increased in Antarctica during decades, primarily due to the logistic and tourism operations, which consequent negative impact on penguin populations, altering their physiological responses. Therefore, we aimed to assess the blood biochemistry and oxidant/antioxidant balance of Adélie penguins (Pygoscelis adeliae) inhabiting two selected colonies: Potter Peninsula, considered as a low impacted colony, and Esperanza/Hope Bay as a high impacted colony. The levels of calcium, uric acid, and fructosamine, showed significant high values (p<0.05) for the Potter Peninsula´s penguins. Besides, this population showed high levels of plasma protein oxidation and erythrocyte lipid peroxidation (p<0.005) while the Esperanza/Hope Bay population presented high levels of erythrocyte protein oxidation and plasma lipid peroxidation (p<0.005). The oxidative damage values were similar in the Potter Peninsula population and slightly lower in the Esperanza/Hope Bay penguins if the results were compared to previous reports. The enzymes superoxide dismutase and glutathione peroxidase had significantly (p<0.005) high activity in the Esperanza/Hope Bay population, which also showed high reduced glutathione levels. The glutathione S-transferase activity was significantly high (p<0.005) in the Potter Peninsula population. The obtained results might take into account for making decisions about management and protection plans for the different penguin nesting areas in Antarctica.

Organic sulfur compositions and their relationships with iron sulfides in Antarctic lake sediments

本文利用有机硫硫同位素组成（δ³⁴S_org）及活性铁的黄铁矿化度（DOP）和硫化度（DOS）研究了南极阿德雷岛受企鹅活动影响的Y2湖和未受影响的菲尔德斯半岛燕鸥湖YO沉积物中有机硫的来源组成及其与铁硫化物的联系.结果表明，Y2沉积物1~15 cm较低的δ³⁴S_org指示有机质硫化形成的贫³⁴S成岩有机硫（S_diag）占比较高，其中在8~15 cm较高的DOS指示铁硫化物形成和有机质硫化同时发生，源于该层位高含量的活性铁供给.Y2剖面48~56 cm沉积物有机硫富集³⁴S显著，对应于企鹅数量高峰期，表明大量企鹅粪的外部输入使沉积物中富³⁴S的生物有机硫（S_bio）快速增加，并超过了内部硫转化过程中成岩有机硫的增加.YO沉积物在28 cm处δ³⁴S_org显著降低，主要是由于该层位硫酸盐异化还原强，有机质硫化形成的大量S_diag成为有机硫的主要成分，同位素质量平衡计算结果显示该层位S_diag占比高达95.4%；同时，28 cm处较高的DOP指示沉积物黄铁矿的形成与有机质硫化同时发生，主要源自沉积物中高硫酸盐还原强度产生了足够多的硫化氢前体.本研究表明，有机硫组分的来源转化与有机质、活性铁紧密耦合，对区域湖泊有机质成岩埋藏及潜在的气候环境效应具有重要的指示意义.;Sulfur isotope ratios of organic sulfur (δ³⁴S_org), degrees of pyritization (DOP) and sulfurization (DOS) in sediments were analyzed to reveal the organic sulfur compositions and their relationships with iron sulfides in a penguin-affected lake Y2 and a pristine Yanou Lake (YO) at Ardley Island and Fildes Peninsula, Antarctica, respectively. The depleted δ³⁴S_org values in Y2 sediments of 1-15 cm indicated a high proportion of ³⁴S-depleted diagenetic organic sulfur (S_diag) in total sulfur. Meanwhile, the high DOS in Y2 sediments of 8-15 cm indicated a concurrent sulfurization of iron and the organic matter, likely due to the high availability of active iron in this layer. The observed much enriched δ³⁴S_org in Y2 sediments of 48-56 cm corresponding to the period of high penguin populations, which indicated that large external inputs of penguin guanos result in a rapid increase in ³⁴S-enriched biological organic sulfur (S_bio) in the sediments, and exceeds the S_diag that from the internal sulfur transformations. The depleted δ³⁴S_org in YO sediment of 28 cm indicates a high proportion (95.4%) of ³⁴S-depleted S_diag which was from strong sulfurization of organic matter, corresponding to the strongest sulfate reduction in this layer. Meanwhile, the high DOP in YO sediment of 28 cm indicated a concurrent formation of pyrite sulfur and the sulfurization of organic matter in this layer, due to the high available precursors of hydrogen sulfide and/or intermediate species of sulfur from the sulfate reduction. Our study indicates that the components of organic sulfur are coupled tightly with organic matter and reactive iron and provides a direct implication for the depositions of organic matter and thus the potential climatic and environmental effects in regional aquatic ecosystems.

Genetic diversity and structure of captive gentoo penguin populations in Japan.

Until the last decade, gentoo penguins were usually split into two subspecies, northern gentoo penguins (Pygoscelis papua papua) breeding in the Falkland Islands, South Georgia, and other subantarctic islandsand southern gentoo penguins (P. papua ellsworthi) breeding in the South Sandwich, South Orkney and South Shetland islands, and Antarctic Peninsula. Recent genetics research, however, suggests that the population at South Georgia is much more closely related to those further southand should be included in P. papua ellsworthi. In Japanese zoos and aquariums, captive breeding of gentoo penguins is conducted separately in three populations: "Captive-South Georgia,"originating from South Georgia, "Captive-South Shetlands,"originating from South Shetlands, and "Captive-Unknown,"originating from at least one founder of unknown subspecies. The aims of the present study were to investigate the genetic diversity and differentiation of these captive populations using microsatellite analysis. Genetic diversity in each captive population was similar to that found in the wild, although they had much lower contemporary effective population sizes. Pairwise genetic differentiation indexes (FST ) among the three captive populations were as follows: 0.0309 ("Captive-South Georgia" and "Captive-Unknown"), 0.1094 ("Captive-South Georgia" and "Captive-South Shetlands"), and 0.1214 ("Captive-South Shetlands" and "Captive-Unknown"). Using Bayesian clustering, there was relatively high genetic differentiation between the "Captive-South Shetlands" group, which formed a distinct cluster, and individuals of the "Captive-Unknown" group, which were assigned to clusters in common with "Captive-South Georgia."The results from the present study are useful for future management of captive gentoo penguin populations in Japan.

Where’s the best supermarket deal? Female Southern Rockhopper Penguins (Eudyptes chrysocome) show variable foraging areas during the guard stage at Isla de los Estados, Argentina

Understanding the spatial distribution of seabirds contributes to comprehending their ecological requirements and dispersion patterns. We studied the at-sea distribution of female Southern Rockhopper Penguins (Eudyptes chrysocome (J.R. Forster, 1781)) at Isla de los Estados colony during the early chick-rearing period. We used a clustering analysis approach to identify different groups according to the foraging trip (tracking and diving data from GPS and temperature and depth data loggers) and diet (δ15N composition on blood samples) characteristics. Foraging trips differed in duration, location, and dive depths explored. Females in clusters 1 and 3 traveled longer distances and in opposite directions (36.3 ± 21.3 and 40.3 ± 14.0 km, respectively). Females in cluster 2 fed closer to the colony (16.8 ± 7.8 km). Dives occurred in pelagic habitats. Higher δ15N values suggested a greater proportion of fish (e.g., the Fuegian sprat, Sprattus fuegensis (Jenyns, 1842)) consumption in the northern foraging areas (cluster 1). The variability observed in the spatial distribution suggests flexibility in the foraging behavior of Southern Rockhopper Penguins and availability of adequate foraging areas within the colony range during the early chick-rearing period, both important features for Southern Rockhopper Penguin population. These results contribute to understanding the use of the Southern Ocean by marine mesopredators and top predators and to the marine spatial planning in the area.

Correction to 'Bayesian inference reveals positive but subtle effects of experimental fishery closures on marine predator demographics'.

Correction to 'Bayesian inference reveals positive but subtle effects of experimental fishery closures on marine predator demographics'.

South Africa's experimental fisheries closures and recovery of the endangered African penguin

Abstract In a scientifically-transformative project, South Africa implemented a decade-long field experiment to understand how fisheries may be affecting its most iconic seabird, the African penguin Spheniscus demersus. This unique effort prohibits the take of anchovy and sardine within relatively small areas around four African penguin breeding colonies, two in the Benguela upwelling ecosystem and two in the adjacent Agulhas region. For the Benguela, fisheries closures within the birds’ primary foraging range increased their breeding productivity and perhaps reduced parental foraging efforts, indicating that the fisheries are competing with the birds for food. Results were less clear for foraging behaviour in the Agulhas, but no data on breeding success were collected there. The African penguin is endangered, its population continues to decline, and fisheries closures have been demonstrated to improve demographic traits that contribute to population growth. Therefore, given the critical status of the species, fisheries closures should be maintained, at least at Dassen Island where the population has great capacity to expand and support other nearby colonies. Continuing or implementing corresponding fisheries closures in the Agulhas region is also warranted, as well as creating and testing the value of pelagic closed areas during the non-breeding season when the penguins disperse widely across these ecosystems. These management actions would increase penguin food supplies and may help to meet societal goals of halting the decline of the penguin population, as well as maintaining the economic and cultural services provided by fisheries and ecotourism.

Sex and Age Differences in Activity Budgets in a Population of Captive African Penguins (Spheniscus demersus)

ABSTRACT The African penguin (Spheniscus demersus) is an endangered species that continues to experience population decline. Understanding the behavior of this species is a critical step in the conservation efforts to prevent their extinction. A comprehensive activity budget of this species has yet to be conducted in any captive population, which are critical for the Species Survival Plan (SSP) breeding programs. We performed scan sampling observations on a group of 19 penguins to construct an activity budget. We also investigated the behavioral differences between males and females, as well as between adults and juveniles. Results indicate there are minimal sex differences in time budget allocations, but there are some notable age related differences. Creating and comparing activity budgets between populations are critical for understanding animal welfare in captive settings.

Aptenodytes Forsteri Optimization: Algorithm and applications

This paper proposes a new naturally inspired swarm intelligence algorithm called the Aptenodytes Forsteri Optimization Algorithm (AFO). The main inspiration is the emperor penguin’s warm-hugging behaviour. When looking for a suitable location, emperor penguins need to sense the change of temperature, consider the location of other penguins, move closer to the centre of the penguin population, minimize their energy loss, and refer to their memory. These five strategies are evolved into five update modes of variables. According to the characteristics of these update modes in the exploration and exploitation stage, adaptive adjustment methods are designed to mix the five ways. The effectiveness of the proposed AFO is checked, through a comparison with other nature-inspired algorithms, on shifted classical benchmark problems and CEC2017 benchmark problems. Moreover, four engineering problems are utilized to estimate the effectiveness of AFO in optimizing constrained problems. The experimental results show that AFO has the best performance in most problems, which can be considered an excellent and competitive algorithm. In addition, as for the problem of partial algorithm update bias towards the origin, particular experiments and metrics are designed to examine the impact of such update methods on the generality of the algorithm. Source codes of AFO are publicly available at https://github.com/TwilightArchonYz/A-new-Nature-inspired-optimization-algorithm-AFO.

Effects of Diesel, Heavy Metals and Plastics Pollution on Penguins in Antarctica: A Review.

Simple SummaryAntarctica is contaminated by anthropogenic pollution. Due to the persistent low temperatures, the toxic impacts of pollution to the environment can be extensive. The severity of the effects varies according to the animal species, chemical type and level of exposure. Penguins are at major risk as they are the most prominent group of animals in Antarctica. This review highlights the background of penguins in Antarctica, the anthropogenic pollution and cases, as well as the toxic effects of diesel, heavy metals and microplastics toward penguins. A bibliometric analysis is also included.Antarctica is a relatively pristine continent that attracts scientists and tourists alike. However, the risk of environmental pollution in Antarctica is increasing with the increase in the number of visitors. Recently, there has been a surge in interest regarding diesel, heavy metals and microplastics pollution. Contamination from these pollutants poses risks to the environment and the health of organisms inhabiting the continent. Penguins are one of the most prominent and widely distributed animals in Antarctica and are at major risk due to pollution. Even on a small scale, the impacts of pollution toward penguin populations are extensive. This review discusses the background of penguins in Antarctica, the anthropogenic pollution and cases, as well as the impacts of diesel, heavy metals and microplastics toxicities on penguins. The trends of the literature for the emerging risks of these pollutants are also reviewed through a bibliometric approach and network mapping analysis. A sum of 27 articles are analyzed on the effects of varying pollutants on penguins in Antarctica from 2000 to 2020 using the VOSviewer bibliometric software, Microsoft Excel and Tableau Public. Research articles collected from the Scopus database are evaluated for the most applicable research themes according to the bibliometric indicators (articles, geography distribution, annual production, integrated subject areas, key source journals and keyword or term interactions). Although bibliometric studies on the present research theme are not frequent, our results are sub-optimal due to the small number of search query matches from the Scopus database. As a result, our findings offer only a fragmentary comprehension of the topics in question. Nevertheless, this review provides valuable inputs regarding prospective research avenues for researchers to pursue in the future.

Intraspecific Variation in Mercury, δ15 N, and δ13 C Among 3 Adélie Penguin (Pygoscelis adeliae) Populations in the Northern Antarctic Peninsula Region.

Mercury (Hg) is a pervasive environmental contaminant that accumulates in the organs and tissues of seabirds at concentrations capable of causing acute or long-term adverse health effects. In the present study, Hg concentrations in Adélie penguin (Pygoscelis adeliae) egg membranes and chick feathers served as a proxy for Hg bioavailability in the marine environment surrounding the northern Antarctic Peninsula. Stable isotopes were measured in conjunction with Hg to infer information regarding feeding habits (δ15 N, diet/trophic level; δ13 C, foraging habitat). The Hg concentrations were low relative to toxicity benchmark values associated with adverse health effects in birds and ranged between 0.006 and 0.080 µg g-1 dry weight (n = 65) in egg membranes and 0.140 to 1.05 µg g-1 fresh weight (n = 38) in feathers. Egg membrane δ15 N signatures suggested that females from different breeding colonies had similar diets consisting of lower and higher trophic prey prior to arrival to breeding grounds. In contrast, δ15 N signatures in feathers indicated that chick diet varied by colony. The Hg concentrations demonstrated significant positive relationships with δ15 N, providing support for the hypothesis of Hg biomagnification up the food chain. The δ13 C signatures in both tissue types provided evidence of foraging habitat segregation among populations. The differences in Hg exposure and foraging ecology suggest that each colony has localized foraging behaviors by breeding adults that warrant additional investigation.Environ Toxicol Chem 2021;40:2791-2801. © 2021 SETAC.

Quantifying the causes and consequences of variation in satellite‐derived population indices: a case study of emperor penguins

AbstractVery high‐resolution satellite (VHR) imagery is a promising tool for estimating the abundance of wildlife populations, especially in remote regions where traditional surveys are limited by logistical challenges. Emperor penguins Aptenodytes forsteri were the first species to have a circumpolar population estimate derived via VHR imagery. Here we address an untested assumption from Fretwell et al. (2012) that a single image of an emperor penguin colony is a reasonable representation of the colony for the year the image was taken. We evaluated satellite‐related and environmental variables that might influence the calculated area of penguin pixels to reduce uncertainties in satellite‐based estimates of emperor penguin populations in the future. We focused our analysis on multiple VHR images from three representative colonies: Atka Bay, Stancomb‐Wills (Weddell Sea sector) and Coulman Island (Ross Sea sector) between September and December during 2011. We replicated methods in Fretwell et al. (2012), which included using supervised classification tools in ArcGIS 10.7 software to calculate area occupied by penguins (hereafter referred to as ‘population indices’) in each image. We found that population indices varied from 2 to nearly 6‐fold, suggesting that penguin pixel areas calculated from a single image may not provide a complete understanding of colony size for that year. Thus, we further highlight the important roles of: (i) sun azimuth and elevation through image resolution and (ii) penguin patchiness (aggregated vs. distributed) on the calculated areas. We found an effect of wind and temperature on penguin patchiness. Despite intra‐seasonal variability in population indices, simulations indicate that reliable, robust population trends are possible by including satellite‐related and environmental covariates and aggregating indices across time and space. Our work provides additional parameters that should be included in future models of population size for emperor penguins.

6,000‐Year Reconstruction of Modified Circumpolar Deep Water Intrusion and Its Effects on Sea Ice and Penguin in the Ross Sea

AbstractThe Ross Sea has the world's largest marine protected area. Modified Circumpolar Deep Water (MCDW) has significant effects on physical and biological processes in the Ross Sea. Totally 13 penguin ornithogenic sediment profiles were collected from Inexpressible Island, Ross Sea, and the Cd/P ratios were used as a proxy of MCDW intrusion, enabling to reconstruct the variability of MCDW intrusion into the Ross Sea during the past 6,000 years. During the intervals of ∼0.7–1.6 and ∼2.8–6.0 kyr BP, enhanced MCDW intrusion increased the heat supply which warmed the surface water and reduced the coastal sea ice concentration. By contrast, reduced MCDW intrusion during ∼1.6–2.8 kyr BP caused a decrease in the penguin population via restricting food supply and/or increasing sea ice concentration. Thus, changes in MCDW were responsible for driving millennial changes in sea ice and penguin population in the Ross Sea.

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.

How animals distribute themselves in space: energy landscapes of Antarctic avian predators

BackgroundEnergy landscapes provide an approach to the mechanistic basis of spatial ecology and decision-making in animals. This is based on the quantification of the variation in the energy costs of movements through a given environment, as well as how these costs vary in time and for different animal populations. Organisms as diverse as fish, mammals, and birds will move in areas of the energy landscape that result in minimised costs and maximised energy gain. Recently, energy landscapes have been used to link energy gain and variable energy costs of foraging to breeding success, revealing their potential use for understanding demographic changes.MethodsUsing GPS-temperature-depth and tri-axial accelerometer loggers, stable isotope and molecular analyses of the diet, and leucocyte counts, we studied the response of gentoo (Pygoscelis papua) and chinstrap (Pygoscelis antarcticus) penguins to different energy landscapes and resources. We compared species and gentoo penguin populations with contrasting population trends.ResultsBetween populations, gentoo penguins from Livingston Island (Antarctica), a site with positive population trends, foraged in energy landscape sectors that implied lower foraging costs per energy gained compared with those around New Island (Falkland/Malvinas Islands; sub-Antarctic), a breeding site with fluctuating energy costs of foraging, breeding success and populations. Between species, chinstrap penguins foraged in sectors of the energy landscape with lower foraging costs per bottom time, a proxy for energy gain. They also showed lower physiological stress, as revealed by leucocyte counts, and higher breeding success than gentoo penguins. In terms of diet, we found a flexible foraging ecology in gentoo penguins but a narrow foraging niche for chinstraps.ConclusionsThe lower foraging costs incurred by the gentoo penguins from Livingston, may favour a higher breeding success that would explain the species’ positive population trend in the Antarctic Peninsula. The lower foraging costs in chinstrap penguins may also explain their higher breeding success, compared to gentoos from Antarctica but not their negative population trend. Altogether, our results suggest a link between energy landscapes and breeding success mediated by the physiological condition.

Long-term variation in the breeding diets of macaroni and eastern rockhopper penguins at Marion Island (1994–2018)

Populations of the macaroni penguin Eudyptes chrysolophus and the eastern rockhopper penguin E. filholi breeding at Marion Island (Prince Edward Islands) in the sub-Antarctic Indian Ocean decreased from 1994 to 2018. We examined their diets when rearing chicks during this period. There was substantial overlap in the diets of the two species, with crustaceans, dominated by the euphausiids Thysanoessa vicina and Euphausia vallentini, making up >80% of the diets by number and >60% by mass over the study period. The lanternfishes Krefftichthys anderssoni and Protomyctophum tenisoni were the most-commonly consumed fish in the diet of breeding macaroni penguins and dominated in their diet in three of the 25 years (1994, 1998 and 2014); they were also the most commonly consumed fish by eastern rockhopper penguins. Macaroni penguins consumed more of the amphipod crustacean Themisto gaudichaudii and the lanternfish Electrona carlsbergi as well as a greater diversity of and larger-sized fish than did eastern rockhopper penguins. The horsefish Zanclorhynchus spinifer was found in substantial amounts in the diet of eastern rockhopper penguins in 1996 and 1997. Despite annual variations in relative prey contributions to the diets, there were no significant long-term changes in the diet of either penguin species over the study period or when compared with an earlier assessment in 1982. We conclude that changes in the relative proportions of prey in the diets of these penguin species during breeding are unlikely to account for the recent declines in these penguin populations.

Vector incrimination and transmission of avian malaria at an aquarium in Japan: mismatch in parasite composition between mosquitoes and penguins

BackgroundCaptive populations of penguins outside of their natural distributions are often maintained in outdoor facilities, such as zoos and aquariums. Consequently, such penguins in captivity are constantly exposed to mosquito vectors and risk of avian malarial infection during their active period from spring to autumn, which can be lethal to these naïve birds. Previous studies have investigated parasite prevalence in mosquitoes or penguins, but simultaneous investigations, which would be crucial to monitor the transmission dynamics and cycle within a facility, have not been done. To identify dominant lineages and trends, multiple-year surveys are recommended.MethodsAvian malaria parasites (Plasmodium spp.) and related haemosporidia were tested in penguins and mosquitoes at an aquarium in Japan through multiple years from 2011 to 2018. Prevalence and dynamics were confirmed, and molecular analyses targeting the protozoal cytb gene were used to reveal the transmission cycle. Blood meals of mosquitoes were also identified using molecular methods.ResultsParasite detection in penguins tended to fluctuate within an individual. Two Plasmodium lineages were consistently detected in mosquitoes that had fed on penguins and wild birds observed around the aquarium. Plasmodium lineage CXPIP09 was detected from both mosquitoes and penguins, suggesting active transmission at this facility. However, Plasmodium cathemerium PADOM02 was only detected in mosquitoes, which may be due to host, vector or parasite-related factors, or detection methods and their limits. Additionally, Haemoproteus larae SPMAG12 was detected from penguins, suggesting active transmission via biting midges.ConclusionsThe mismatch in parasite composition between penguins and mosquitoes shows that multiple aspects such as captive birds, wild birds and vector insects should be monitored in order to better understand and control avian malarial infection within ex-situ conservation facilities. Furthermore, morphological analyses would be needed to confirm competency and infection dynamics of avian malaria parasites.