Foraging strategies are of great ecological interest, as they have a strong impact on the fitness of an individual and can affect its ability to cope with a changing environment. Recent studies on foraging strategies show a higher complexity than previously thought due to intraspecific variability. To reliably identify foraging strategies and describe the different foraging niches they allow individual animals to realize, high-resolution multivariate approaches which consider individual variation are required. Here we dive into the foraging strategies of Galápagos sea lions (Zalophus wollebaeki), a tropical predator confronted with substantial annual variation in sea surface temperature. This affects prey abundance, and El Niño events, expected to become more frequent and severe with climate change, are known to have dramatic effects on sea lions. This study used high-resolution measures of depth, GPS position and acceleration collected from 39 lactating sea lion females to analyze their foraging strategies at an unprecedented level of detail using a novel combination of automated broken stick algorithm, hierarchical cluster analysis and individually fitted multivariate hidden Markov models. We found three distinct foraging strategies (pelagic, benthic, and night divers), which differed in their horizontal, vertical and temporal distribution, most likely corresponding to different prey species, and allowed us to formulate hypotheses with regard to adaptive values under different environmental scenarios. We demonstrate the advantages of our multivariate approach and inclusion of individual variation to reliably gain a deeper understanding of the adaptive value and ecological relevance of foraging strategies of marine predators in dynamic environments.

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Amphibious mammal species alternate between foraging at sea and attendance on land. Due to thermoregulatory requirements, they often haul out during the night, making social interactions difficult to observe. We tested the suitability of UHF-proximity loggers for assessing social relationships among Galápagos sea lions Zalophus wollebaeki. To survive periods at sea, proximity loggers were embedded in epoxy. Automatic downloads to receiving stations rendered logger recovery unnecessary. Encounters were logged within a range of 10 m. Logs provided information about interacting individuals as well as time and duration of encounters. 'Received signal strength indicator' values correlated with distance, but were influenced by antenna angle and environmental factors. Laboratory tests and validation in the field demonstrated that the spatial resolution corresponded to 2 m. Data needed to be corrected, as single encounters were recorded as multiple logs and reciprocity of loggings between animals was not always achieved. Digital data correlated with observational data, but associations were 4 times more likely to be detected using proximity loggers. Data revealed that non-territorial males frequently associated for extended periods of time, especially during the night and even outside the study colony. The modified proximity logger system proves an excellent tool to determine social structure in situations where direct observation is limited. KEY WORDS: Amphibious species · Proximity logger · Social structureResale or republication not permitted without written consent of the publisher AQUATIC BIOLOGY

Population monitoring is vital for conservation and management. However, simple counts of animals can be misleading and this problem is exacerbated in seals (pinnipeds) where individuals spend much time foraging away from colonies. We analyzed a 13-year-series of census data of Galapagos sea lions (Zalophus wollebaeki) from the colony of Caamaño, an islet in the center of the Galapagos archipelago where a large proportion of animals was individually marked. Based on regular resighting efforts during the cold, reproductive (cold-R; August to January) and the warm, non-reproductive (warm-nR; February to May) season, we document changes in numbers for different sex and age classes. During the cold-R season the number of adults increased as the number of newborn pups increased. Numbers were larger in the morning and evening than around mid-day and not significantly influenced by tide levels. More adults frequented the colony during the warm-nR season than the cold-R season. Raw counts suggested a decline in numbers over the 13 years, but Lincoln-Petersen (LP-) estimates (assuming a closed population) did not support that conclusion. Raw counts and LP estimates were not significantly correlated, demonstrating the overwhelming importance of variability in attendance patterns of individuals. The probability of observing a given adult in the colony varied between 16% (mean for cold-R season) and 23% (warm-nR season) and may be much less for independent 2 to 4 year olds. Dependent juveniles (up to the age of about 2 years) are observed much more frequently ashore (35% during the cold-R and 50% during the warm-nR seasons). Simple counts underestimate real population size by a factor of 4–6 and may lead to erroneous conclusions about trends in population size.

We analyzed reports of Antarctic and Sub-Antarctic seabirds with migration routes over seven South American countries (Argentina, Brazil, Chile, Ecuador, Peru, Uruguay, and Venezuela). Forty-eight species were reported, observed over oceanic and/or coastal areas. Chile presented the highest number of Antarctic seabird species (39), followed closely by Brazil (38). Diomedea exulans, D. epomophora, Thalassarche melanophris, Macronectes giganteus, Fulmarus glacialoides, Pachyptila desolota and Oceanites oceanicus were the most common species, recorded in six of the seven searched countries. The least reported species were Pygoscelis adeliae, Thalassoica antarctica, Pagodroma nivea, Pachyptila salvini and Pterodroma inexpectata, observed in one country each. According to the IUCN, the species with migration routes over the South American countries are considered endangered (three species), vulnerable (eight species) and near threatened (eight species). Consequently, it is important to protect not only breeding habitats in the Antarctic environment, but their entirely migration routes over South America. Keywords: Pelagic seabirds; conservation areas; biodiversity. RESUMO AVES MARINHAS ANTÁRTICAS E SUB-ANTÁRTICAS RESUMENAVES MARINAS ANTÁRTICAS Y SUB-ANTÁRTICAS EN AMÉRICA DEL SUR: UNA REVISION. Analizamos registros de aves marinas antárticas y sub-antárticas en países de América del Sur (Argentina, Brasil, Chile, Ecuador, Perú, Uruguay y Venezuela) en publicaciones científicas, disertaciones, tesis y libros. Se registraron cuarenta y ocho especies, observadas sobre áreas oceánicas o costeras de los países estudiados. Chile presentó el mayor número de especies migratorias que anidan en la Antártida (39), seguido por Brasil (38). Las especies observadas con mayor frecuencia fueron Diomedea. exulans, D. epomophora, Thalassarche melanophris, Macronectes giganteus, Fulmarus glacialoides, Pachyptila desolota y Oceanites oceanicus; las cuales fueron reportadas en seis de los siete países analizados. Asimismo, las especies con menor frecuencia fueron Pygoscelis adeliae, Thalassoica antarctica, Pagodroma nivea, Pachyptila salvini y Pterodroma inexpectata, observadas apenas en uno sólo de los países analizados. Entre las especies registradas, tres son consideradas especies amenazadas, ocho vulnerables y otras ocho clasificadas como casi amenazadas de acuerdo con IUCN. Consecuentemente, es importante proteger no sólo las áreas de nidificación en el ecosistema Antártico, sino también toda la ruta de migración de estas aves marinas sobre los países de América del Sur. Palabras clave: Aves marinas pelágicas; áreas para conservación; biodiversidad.

Introduction:Threats that affect the avian diversity on the Galápagos Islands are increasing. We evaluated threats such as climate change and severe weather, human intrusions and disturbance, biological resource use, invasive and other problematic species, genes and diseases, pollution, geological events and loss of genetic diversity in relation with avian species enlisted in both the international and national (Ecuador) IUCN Red List, which can be used as sentinel species of the ecosystem. Here, the status of the threatened species for the next ten years (present time up to 2028), under two scenarios, including thestatus quoand theavian diversity visionfor the species’ conservation, was assessed.Methods:The conceptual framework of the assessment was envisioned within the existing knowledge and projections of present and future threats to revisit current conservation efforts. Based on this evaluation, a set of management actions coupled with mitigation strategies to address new anthropogenic threats affecting the long-term survival of species in the face of global and regional environmental changes are recommended. Alternative strategies for species conservation, mainly when declining avian populations are susceptible to demographic bottlenecks or risk of extinction and when natural disasters affect ecosystem stability, are also considered.Results:These results should be envisioned as a guide for the evaluation and management of the avian species in the future to be replicated every decade.

In many mammals, early survival differs between the sexes, with males proving the more fragile sex ["Fragile male (FM) hypothesis"], especially in sexually dimorphic species where males are the larger sex. Male-biased allocation (MBA) by females may offset this difference. Here, we evaluate support for the FM and MBA hypotheses using a dataset on Galapagos sea lions (Zalophus wollebaeki). We statistically model sex-specific survival as it depends on body mass and environmental conditions (sea surface temperature, SST, a correlate of marine productivity) at three developmental stages, the perinatal phase (1st month), the main lactation period (1st year), and the weaning period (2nd year). Supporting the FM hypothesis, we found that, early in life (1st month), at equal birth mass, males survived less well than females. During the remainder of the first year of life, male survival was actually less sensitive to harsh environmental conditions than that of females, contradicting the FM hypothesis and supporting the MBA hypothesis. During the second year of life, only male survival suffered with high SSTs as predicted by the FM hypothesis. At each developmental stage, observed survival rates were almost equal for both sexes, suggesting that mothers buffer against the inherent fragility of male offspring through increased allocation, thereby masking the differences in survival prospects between the sexes.

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