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Rationale: Understanding the migration of marine animals is hindered by the limitations of traditional tracking methods. It is therefore crucial to develop alternative methods. Stable isotope‐based tracking has proven useful for this task, although it requires detailed isoscapes in the focal area. Here, we present predator‐based isoscapes of the coastal zone of the Patagonian Shelf Large Marine Ecosystem (PSLME), which offers a novel tool for geolocation. Methods: Whole‐blood samples from breeding Magellanic penguins nesting at 11 colonies were used to create δ15N and δ13C isoscapes. Isotopic values were assigned to random positions inside their corresponding foraging area. Spatial analysis and data interpolation resulted in δ15N and δ13C isoscapes for the coastal zone of the PSLME, which were validated through cross‐validation. Results: The isoscapes mean standard error ranged from 0.05 to 0.41 for δ15N and from 0.07 to 0.3 for δ13C, similar to the error range of the mass spectrometer used for measuring isotope ratios. Predictive surfaces reflected the latitudinal trends, with δ13C and δ15N values increasing northwards. δ13C values showed a strong latitudinal gradient, while δ15N values had two distinct domains, with higher values in the north. The error surface indicated the highest certainty within 130 km from the shore and within the reported Magellanic penguin foraging areas. Conclusions: Both isoscapes revealed strong spatial variation. The δ13C isoscape showed a latitudinal gradient, consistent with patterns in other oceans. The δ15N isoscape clearly separated northern and southern colonies, likely influenced by nitrogen sources. The error obtained fell within the measurement error ranges, adding credibility to the models. [ABSTRACT FROM AUTHOR]

The relative importance of genetic drift and local adaptation in facilitating speciation remains unclear. This is particularly true for seabirds, which can disperse over large geographic distances, providing opportunities for intermittent gene flow among distant colonies that span the temperature and salinity gradients of the oceans. Here, we delve into the genomic basis of adaptation and speciation of banded penguins, Galápagos (Spheniscus mendiculus), Humboldt (Spheniscus humboldti), Magellanic (Spheniscus magellanicus), and African penguins (Spheniscus demersus), by analyzing 114 genomes from the main 16 breeding colonies. We aim to identify the molecular mechanism and genomic adaptive traits that have facilitated their diversifications. Through positive selection and gene family expansion analyses, we identified candidate genes that may be related to reproductive isolation processes mediated by ecological thermal niche divergence. We recover signals of positive selection on key loci associated with spermatogenesis, especially during the recent peripatric divergence of the Galápagos penguin from the Humboldt penguin. High temperatures in tropical habitats may have favored selection on loci associated with spermatogenesis to maintain sperm viability, leading to reproductive isolation among young species. Our results suggest that genome-wide selection on loci associated with molecular pathways that underpin thermoregulation, osmoregulation, hypoxia, and social behavior appears to have been crucial in local adaptation of banded penguins. Overall, these results contribute to our understanding of how the complexity of biotic, but especially abiotic, factors, along with the high dispersal capabilities of these marine species, may promote both neutral and adaptive lineage divergence even in the presence of gene flow. [ABSTRACT FROM AUTHOR]

We studied the migration of Magellanic penguins near the southern tip of the breeding distribution, and for the first time found evidence of partial migration for this species within the same colony. Forty‐three percent of the penguins studied stayed within ~ 290 km of the colony (residents), while others went northwards as far as 2000 km. All penguins spent the same amount of time at sea and traveled similar total distances, but residents experienced colder waters (2°C lower) and habitats with lower Chlorophyll‐a concentrations than migrants. The two habitats are inhabited by different prey items, consequently offering the penguins distinct prey options. We have shown high variability in the non‐breeding dispersion behavior of Magellanic penguins within the same colony; nonetheless, further research is required to understand the proximate and ultimate causes, and the consequences, of this behavior. [ABSTRACT FROM AUTHOR]

We evaluated the mortality due to aspergillosis in free-ranging Magellanic penguins during their migration and the reproductive season. A total of 98 carcasses of penguins were collected along 370 km of coastline in Southern Brazil, between June 2017 and October 2019, and from reproductive colonies in Patagonian Argentina, in January 2019. All animals were necropsied, and only proven cases were computed. Aspergillosis was diagnosed in 2.5% of the penguins evaluated during their migration route. Our study, of the Southern coast of Brazil, is the first to demonstrate that aspergillosis is an important cause of mortality in free-ranging penguins. The implications of these findings in the One Health context are discussed. [ABSTRACT FROM AUTHOR]

Longline fisheries have grown throughout the world's oceans for more than 40 years. This type of fisheries has captured high-quality fish (mature individuals rather than unwanted juveniles), has had minimal [...]

The overall population size and trend of the Magellanic Penguin (Spheniscus magellanicus) is uncertain and population estimates are available only for few locations. The last complete census along its central-southern distribution range in Argentina, province of Santa Cruz, was made in the 1990s. This study updates the breeding population size along Santa Cruz. Population estimates were compared with the last complete census, and trends were studied when it was possible. With 353,256 estimated breeding pairs, the overall population in Santa Cruz remained relatively stable after 25 years. The Santa Cruz population represents 31% of the Argentine Patagonian coast population and could represent between 22 and 30% of the species' global population. Colony sizes varied between 9 and 127,492 breeding pairs. Changes in abundance differed among locations, with individual colonies showing increasing, decreasing, or stable trends, which suggests that local factors determine population dynamics. The most significant increases (> 40%) were observed in the southern sector of Santa Cruz. Contrary to what was observed at the north of the distribution range in the province of Chubut, where trends of several colonies were inversely related to colony size, in Santa Cruz most of the largest colonies remained stable or even increased from the 1990s onwards. [ABSTRACT FROM AUTHOR]

Egg laying is one of the most important phases in a female bird's breeding cycle. Its cost is high because eggs contain all the resources needed for the development of an embryo. Variation in size and quality of eggs can have important long‐term consequences for offspring survival. Hatching asynchrony is known to influence sibling competition in many bird species. Last‐hatched chicks will have a competitive disadvantage throughout the pre‐fledgling period because they are smaller. The aim of this study was to analyze the effect of hatching asynchrony and egg size variation on the growth and fledging success of Magellanic penguin Spheniscus magellanicus chicks after disentangling the effects of parental condition. We simultaneously manipulated egg size dimorphism, hatching asynchrony and parental condition by performing a cross‐fostering experiment, creating broods with controlled egg size dimorphism and hatching asynchrony in a colony of Magellanic penguins located in Isla Quiroga, Santa Cruz, Argentina. We found that hatching asynchrony had a negative effect on last‐hatched chicks, but this disadvantage was mitigated by egg size dimorphism in their favor. Moreover, females in good condition invest more in second than in first chicks, which, added to a greater investment by foster fathers, leading to offspring fledging in good condition. On the contrary, for the first‐hatched chicks, we found that body condition of the biological father was an important factor for their growth. We conclude that raising more than one chick seems to be a decision based on parental condition throughout the breeding season. [ABSTRACT FROM AUTHOR]

Millions of penguins live in Patagonia, Argentina, but their existence is being threatened by oil pollutants in the seawaters. Tourists do not represent a destructive force although they sometimes compete with the limited resources available in the area. The area, particularly Chubut Province, has the 500-acre Punto Tombo reserve which boasts of having the biggest collection of two-feet-tall Magellanic penguins aside from other animal species such as the Pampas cat and dolphin gulls.

Population connectivity is driven by individual dispersal potential and modulated by natal philopatry. In seabirds, high vagility facilitates dispersal yet philopatry is also common, with foraging area overlap often correlated with population connectivity. We assess the interplay between these processes by studying past and current connectivity and foraging niche overlap among southern rockhopper penguin colonies of the coast of southern South America using genomic and stable isotope analyses. We found two distinct genetic clusters and detected low admixture between northern and southern colonies. Stable isotope analysis indicated niche variability between colonies, with Malvinas/Falklands colonies encompassing the species entire isotopic foraging niche, while the remaining colonies had smaller, nonoverlapping niches. A recently founded colony in continental Patagonia differed in isotopic niche width and position with Malvinas/Falklands colonies, its genetically identified founder population, suggesting the exploitation of novel foraging areas and/or prey items. Additionally, dispersing individuals found dead across the Patagonian shore in an unusual mortality event were also assigned to the northern cluster, suggesting northern individuals reach southern localities, but do not breed in these colonies. Facilitated by variability in foraging strategies, and especially during unfavorable conditions, the number of dispersing individuals may increase and enhance the probability of founding new colonies. Metapopulation demographic dynamics in seabirds should account for interannual variability in dispersal behavior and pay special attention to extreme climatic events, classically related to negative effects on population trends. [ABSTRACT FROM AUTHOR]

The Magellanic penguin Spheniscus magellanicus is a top predator and a major consumer of marine resources in the Patagonian Continental Shelf and worldwide. It is the most migratory of the Spheniscus penguins, but until recently, its migration route was only partially known. Our aims with regard to the Magellanic penguin breeding on Isla Quiroga, Argentina, were: 1) to compare the distribution during the winter period between sexes and 2) in case that habitat is segregated, to evaluate possible proximate causes like competitive exclusion and/or habitat specialization. In March 2017 and 2018, prior to migration, we equipped 26 penguins with MK3/4 geolocators, which were recovered in late September/early October. Penguins dispersed northwards up to 29°S and southwards up to 56°S, near the Beagle Channel, being distributed over 2158 ± 50 km of latitudinal range and showing a large‐scale distribution pattern across longitudes in waters within the continental shelf. We found a longitudinal segregation between sexes in their winter grounds, with males closer to the 200‐m isobath and further from the coastline than females. Morphological and physiological differences between sexes might allow males to dive deeper at a lower cost than females, which could result in a more offshore path for males. This spatial segregation was supported by bulk blood stable isotope values and estimated isotopic niche, which differed between males and females at their arrival from winter breeding grounds, but not while penguin breed and behave as central place foragers in the colony. For the first time in this species, we combined two independent tools, geolocation and stable isotope data, and find that sexual segregation in habitat use could potentially generate an optimal winter foraging strategy for both sexes, precluding potential intersex competition for food. [ABSTRACT FROM AUTHOR]

The annual molt of Southern Rockhopper Penguins, Eudyptes chrysocome, usually takes place at their colonies after a pre-molting foraging trip. In 2016, an unusual number of Rockhopper Penguins was found molting, and in part subsequently dying, along the southernmost portion of the Argentine coast, far from the main colonies. To report the extent of this dispersion and mortality event, a survey was conducted between February and May 2016 along the southern Patagonian coast. A total of 1039 molting Rockhopper Penguins were reported. The mortality, mainly attributed to starvation, varied between 40 and 89%, according to sites. Furthermore, as adverse oceanographic conditions are known to affect prey availability and penguin’s survival, chlorophyll a concentrations (as a primary productivity index) and sea surface temperatures were analyzed at main foraging grounds. The results showed lower chlorophyll a and sea surface temperature values close to the main colonies during 2016 (compared to average 2003-2015). Although these values alone cannot explain such mortality (as similar low values already occurred in some of the previous year without inducing mortality events), our results support the hypothesis of a reduction in primary productivity close to the main colonies prior to the molt, inducing penguins to move towards more distant foraging grounds, which finally led them to molt later and away from their colonies. Although the oceanographic processes were not fully understood, this event highlights the serious effects that unusual conditions prior to molting can pose on the survival of this endangered penguin, in a context of climate variability. [ABSTRACT FROM AUTHOR]

Rationale: Food provisioning is considered one of the main traits affecting offspring fitness. Differences in food provisioning between sexes, particularly in dimorphic species, could affect the amount and type of food provided, due to differences in the amount of food carried to the nest as a result of differential resources exploitation. Quantitative evidence for sexual differences in food provisioning by parents in penguins is scarce. The Magellanic penguin is moderately sexually dimorphic and breeds along a broad latitudinal range, with birds north and south of this range being essentially dietary specialists while those at intermediate latitudes consume a more diverse diet. Methods: We used stable isotope analysis of carbon and nitrogen by isotope ratio mass spectrometry to examine if there was a differential parental contribution to chicks in ten Magellanic penguin colonies throughout its latitudinal breeding distribution. We used the heuristic Euclidean isotopic distance (ED) and individual isotope distances between the chicks and their parents as a proxy for diet similarity (the smaller the distance, the more similar the diet). Results: The analysis showed that chicks tended to have a more similar diet to that of their male parent and that this pattern was more evident at colonies and in seasons where penguins had a more diverse diet, which could be explained by differences in diet between parents. Distance in δ15N values, but not in δ13C values, differed between both sexes and their chicks in all the pairs sampled, suggesting that δ15N values drive the differences found in ED between chicks and their parents. Conclusions: We have developed an approach that provides the first assessment of the extent of differential food provisioning between male and female Magellanic penguins. Results suggest chicks have a diet more similar to that of their male parent, probably related to the higher trophic level of male penguin prey. [ABSTRACT FROM AUTHOR]

For seabirds, nest site features are an important factor that determines reproductive success. During three breeding seasons (2010-2012), we visited two coastal cliff colonies of Red-legged Cormorants Phalacrocorax gaimardi in the Ría Deseado, Argentina, and studied how nest site characteristics influenced their breeding success. We measured six physical characteristics at 46 nest sites, and we counted the number of fledglings produced each year from each nest (breeding success). We also related nest site temperature and wind exposure with nest site orientation. Breeding success was higher at nest sites with a broad base (greater capacity for holding young) and at nests that were less exposed to winds greater than 25 knots (46.25 km/h), which were sites with a north orientation. The lowest breeding success was observed in nest sites that were exposed to the strongest winds (i.e., sites with a south orientation). Strong winds often blow eggs and chicks away from the nests and increase opportunistic predation by gulls Larus sp. No significant relationship was found between nest site orientation and nest site temperature. Breeding success decreased with the distance to the nearest nest, which agrees with the idea that higher density of reproductive individuals reduces effectiveness of predators. Nest cover, distance from the top of the cliff, and distance from the tide line had no effect on breeding success at this study scale. Our results suggested that nest site characteristics that were related to protection against adverse weather conditions (e.g., strong winds) and avian predation, in combination with a suitable nest space, determined the breeding success of Red-legged Cormorants. [ABSTRACT FROM AUTHOR]

In many bird species, eggs in a brood hatch within days of each other, leading to a size asymmetry detrimental to younger siblings. Hatching asynchrony is often thought of as an adaptive strategy, and the most widely studied hypothesis in relation to this is the 'brood reduction hypothesis'. This hypothesis states that when food resources are unpredictable, hatching asynchrony will allow the adjustment of the brood size maximizing fledging success and benefitting parents. The Magellanic penguin Spheniscus magellanicus is an appropriate species to test this hypothesis because it has a 2-egg clutch that hatches over a 2-d interval with a broad range of variation (-1 to 4 d), it shows facultative brood reduction, and food abundance between breeding seasons is variable. We performed a manipulative study at Isla Quiroga, Argentina, during three breeding seasons (2010-2012) by forcing broods to hatch synchronously (0 d) or asynchronously (2 or 4 d). Years were categorized based on estimated food abundance. Our study provided mixed results because in the low estimated food abundance year asynchronous broods did not have higher nestling survival than synchronous broods, and the second-hatchling in asynchronous broods did not die more often than those in synchronous broods. On the other hand, younger siblings of 4-d asynchronous broods starved earlier than those of synchronous broods, and 2-d asynchronous broods fledged heavier young than synchronous broods. Asynchronous hatching would seem to benefit reproduction in this species, not with respect to survival, but in terms of the advantages it can accord to nestlings and, in terms of lower costs, for parents raising nestlings. [ABSTRACT FROM AUTHOR]

The available information about the feeding habits and preferences of the Red-legged Cormorant (Phalacrocorax gaimardi) generally suggests that this near-threatened South American cormorant is a sedentary benthic forager that also incorporates pelagic prey in its diet. In order to describe the dietary composition and assess the importance of certain prey types (pelagic vs benthic), we studied the diet of this cormorant on the Argentine Atlantic coast during four breeding seasons, using a combined technique of conventional diet assessment (pellets) and stable isotope analysis. Our results show that the Red-legged Cormorant forages mainly on pelagic and demersal—pelagic prey. Results of both techniques showed the main prey to be the Patagonian Sprat, a small high-energy-content pelagic forage fish, and the Patagonian Squid, a low-energy-content demersal—pelagic invertebrate. We also found an overall low prey diversity and important interannual variation for the main prey types, as well as variation between the different breeding stages. This study therefore contributes new and unambiguous information about the Red-legged Cormorant's use of trophic resources and suggests that the combination of a conventional technique with stable isotope analysis provides a solid framework for this seabird diet assessment. [ABSTRACT FROM PUBLISHER]

The evolutionary and adaptive potential of populations or species facing an emerging infectious disease depends on their genetic diversity in genes, such as the major histocompatibility complex ( MHC). In birds, MHC class I deals predominantly with intracellular infections (e.g., viruses) and MHC class II with extracellular infections (e.g., bacteria). Therefore, patterns of MHC I and II diversity may differ between species and across populations of species depending on the relative effect of local and global environmental selective pressures, genetic drift, and gene flow. We hypothesize that high gene flow among populations of Humboldt and Magellanic penguins limits local adaptation in MHC I and MHC II, and signatures of selection differ between markers, locations, and species. We evaluated the MHC I and II diversity using 454 next-generation sequencing of 100 Humboldt and 75 Magellanic penguins from seven different breeding colonies. Higher genetic diversity was observed in MHC I than MHC II for both species, explained by more than one MHC I loci identified. Large population sizes, high gene flow, and/or similar selection pressures maintain diversity but limit local adaptation in MHC I. A pattern of isolation by distance was observed for MHC II for Humboldt penguin suggesting local adaptation, mainly on the northernmost studied locality. Furthermore, trans-species alleles were found due to a recent speciation for the genus or convergent evolution. High MHC I and MHC II gene diversity described is extremely advantageous for the long-term survival of the species. [ABSTRACT FROM AUTHOR]

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Rationale The use of stable isotopes for ecological studies has increased exponentially in recent years. Isotopic trophic studies are based on the assumption that animals are what they eat plus a discrimination factor. The discrimination factor is affected by many variables and can be determined empirically. The Magellanic penguin is a highly abundant marine bird that plays a key role in the southern oceans. This study provides the first estimation of the Magellanic penguin blood discrimination factor for 13C and 15N. Methods A two and a half month feeding experiment was performed, in which ten captive penguins were fed their main natural prey (anchovy Engraulis anchoita). The discrimination factors were estimated by comparing anchovy δ13C and δ15N values (obtained with isotope ratio mass spectrometry using lipid-extracted and bulk anchovy muscle) with penguin blood δ13C and δ15N values. Results Penguin blood was shown to be enriched, compared with anchovies, for 13C and 15N. No changes were observed in the stable isotope ratios of anchovies and discrimination factors during the experiment. The overall discrimination factors were 0.93 ± 0.12 (bulk) and 0.41 ± 0.12 (lipid-free) for 13C; and 2.81 ± 0.17 (bulk) and 2.31 ± 0.17 (lipid-free) for 15N. Conclusions Having an accurate discrimination factor for the studied species is key in any trophic or food web isotopic study. Comparisons of estimated diet-to-blood discrimination factors with published values of aquatic piscivore birds showed that the 13C discrimination factor is particularly variable, and therefore ecologists should be cautious when using a surrogate value from other species. In this study, the Magellanic penguin discrimination factor of a tissue that does not require euthanasia was obtained, a fundamental input for trophic isotopic modeling of the species. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]