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Seabirds coexist within colonies yet the role of conspecifics, whilst foraging is still poorly understood. In the 2019/20 and 2020/21 breeding seasons Magellanic penguins Spheniscus magellanicus and Gentoo penguins Pygoscelis papua were equipped with video loggers and GPS devices (n = 3 and n = 2, respectively) or only GPS devices (n = 11 and n = 2) at Martillo Island (54°54′ S, 67°23′ W), Argentina and compared with GPS tracks from previous seasons (2014, 2015 and 2017). Magellanic penguins transited in groups with conspecifics to the feeding grounds (up to 13 individuals were recorded simultaneously) in search of pelagic Fuegian sprat Sprattus fuegensis, but then were not filmed in close company of conspecifics during prey capture. Gentoo penguins generally fed on Nototheniid sp. at the seafloor. Contrary to predictions, Gentoo penguins foraged with conspecifics in small groups of 2–4 individuals, they coordinated to dive down, search and ambush prey. Gentoo penguins were also recorded foraging pelagically on Fuegian sprat. Conspecifics play an important role either during the initial search for prey patches, particularly when searching for elusive pelagic prey or during the small-scale search and hunt for benthic prey hidden in the seafloor substrate. The presence of conspecifics seems to be important during foraging for Magellanic and Gentoo penguins and this may be reflecting a positive aspect of coloniality. [ABSTRACT FROM AUTHOR]

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Optimal foraging theory predicts an inverse relationship between the availability of preferred prey and niche width in animals. Moreover, when individuals within a population have identical prey preferences and preferred prey is scarce, a nested pattern of trophic niche is expected if opportunistic and selective individuals can be identified. Here, we examined intraspecific variation in the trophic niche of a resident population of striated caracara (Phalcoboenus australis) on Isla de los Estados (Staten Island), Argentina, using pellet and stable isotope analyses. While this raptor specializes on seabird prey, we assessed this population's potential to forage on terrestrial prey, especially invasive herbivores as carrion, when seabirds are less accessible. We found that the isotopic niche of this species varies with season, age, breeding status, and, to a lesser extent, year. Our results were in general consistent with classic predictions of the optimal foraging theory, but we also explore other possible explanations for the observed pattern. Isotopic niche was broader for groups identified a priori as opportunistic (i.e., nonbreeding adults during the breeding season and the whole population during the nonbreeding season) than it was for individuals identified a priori as selective. Results suggested that terrestrial input was relatively low, and invasive mammals accounted for no more than 5% of the input. The seasonal pulse of rockhopper penguins likely interacts with caracara's reproductive status by constraining the spatial scale on which individuals forage. Niche expansion in spatially flexible individuals did not reflect an increase in terrestrial prey input; rather, it may be driven by a greater variation in the types of marine prey items consumed. [ABSTRACT FROM AUTHOR]

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• We conducted surveys on nature relatedness and soundscape perception in Argentina. • Hearing was of secondary importance to vision in experiences of nature. • Nature relatedness was positively correlated with valuation of natural soundscapes. • Valuation of natural soundscapes was higher than that of technophonic soundscapes. • Natural-soundscape-based educational programs may help promote nature relatedness. Human disconnection from nature is thought to have contributed to the environmental crises we currently face, and increasing connection with nature has been proposed as one way of promoting pro-environmental behavior, nature conservation, and social-ecological sustainability. Some efforts to increase connection with nature ("nature relatedness") have centered on exploring the social-ecological importance of soundscapes, but there is a paucity of empirical evidence supporting the theoretical linkage between soundscape perception and nature relatedness. Using prerecorded and in situ soundscape prompts, we conducted a street intercept survey in Ushuaia, Tierra del Fuego, Argentina to assess: 1) the relative importance of senses in experiences of nature, 2) the relationship between nature relatedness and soundscape perception, 3) differences in soundscape perception between various soundscapes, and 4) possible sociodemographic influences on sense importance, nature relatedness, and soundscape perception. Participants reported that hearing was of secondary importance to vision in experiences of nature. We also found that nature relatedness was positively correlated with the valuation of soundscapes—particularly more natural ones—but not with the discernment of soundscapes or identification of where soundscapes were recorded. Valuation of more natural soundscapes was higher than valuation of more technophonically dominated soundscapes, while soundscape discernment and location identification were higher for soundscapes that were likely more familiar to listeners. Sociodemographic influences on these variables were minor, but women reported higher sense importance, and having a nature-based occupation was associated with higher nature relatedness and valuation of a soundscape from a penguin colony. Our study highlighted a number of potential research areas concerning soundscape perception, including differences between prerecorded and in situ soundscape prompts, defining various aspects of soundscape perception, and the relative influences of sound sources and quantitative acoustic parameters on soundscape perception. Further research is certainly needed to account for global diversity in cultures and soundscapes, but we found some promising empirical support for the use of natural-soundscape-focused educational programs in efforts to promote nature relatedness. [ABSTRACT FROM AUTHOR]

The time seabirds have to forage is restricted while breeding, as time at sea must be balanced against the need to take turns with the partner protecting the nest site or offspring, and timing constraints change once the breeding season is over. Combined geolocator-immersion devices were deployed on eleven Imperial Shags (four males and seven females) in Argentina (43°04′S; 64°2′W) in November 2006 and recovered in November 2007. During the breeding season, females foraged throughout the morning, males exclusively in the afternoon, and variability between individuals was low. Outside the breeding season, both sexes foraged throughout the day, and variability between individuals was high. Timing differences may be explained by higher constraints on foraging or greater demands of parental duties experienced by the smaller sex, females in this case. Sexual differences in reproductive role, feeding habits or proficiency can also lead to segregation in timing of foraging, particularly while breeding. [ABSTRACT FROM AUTHOR]

Abstract: The American mink (Neovison vison) is a semi-aquatic, generalist carnivore released onto Tierra del Fuego (TDF) Island in the 1940s, subsequently spreading to adjacent islands in the archipelago with potential effects on native prey populations. Knowledge of this new predator''s trophic ecology is essential to identify threats, plan control strategies and conserve native fauna. We studied seasonal mink diet in TDF in different habitats. We identified undigested remains from 493 scats collected between May 2005 and March 2009 along marine coasts and freshwater shores (rivers and lakes). Small mammals and fish were the main mink prey in TDF (over 65% of diet items). Seasonal variations were not detected, but diet did vary significantly between marine and freshwater habitats, where more terrestrial items were consumed. Among mammals, mink consumed more small native rodents than exotic species. Native fish consumption was also important with greater representation of species from the families Nototheniidae and Galaxiidae in marine and freshwater habitats respectively. Birds were the third item in importance, but did not constitute a particularly large part of the mink''s diet on TDF. Overall, differences found in mink diet between habitats reflected their generalist/opportunistic feeding behaviour and did not differ greatly from observations in its native range or in other areas where it has been introduced. Our results establish the interactions between this novel predator and its prey and also illustrate the need to continue research on native prey populations to quantify mink impact on them and understand the ecological context of this biotic assemblage. [Copyright &y& Elsevier]

The present article is the first formal record of pelagic swarms and beach strandings of the squat lobster Munida gregaria in the Beagle Channel, southern South America. To describe size composition and natural diet of beach strandings and swarms, samples from strandings were taken in April 2007, March 2008 and March 2010. Samples from swarms were taken in May 2007 and April 2010. Also, during November 2008 and January 2009, two acoustic surveys were carried out to describe both, horizontal distribution and school metrics of swarms. Pelagic swarms and beach strandings were composed of 100% individuals of the morph gregaria of M. gregaria. Mean size of males and females in both, beach strandings and swarms, were similar. The diet of pelagic M. gregaria was composed mainly of crustaceans, unicellular algae and small macroalgae, sediment and particulate organic matter. Swarms of pelagic Munida took the shape of extended layers of varying density and height. Their positions in the water column were also variable: swarms were found at different depths, from the subsurface layer to near the sea bottom. Occasionally, some large swarms occupied most of the water column. In the Beagle Channel, SW winds during spring tides could be a forcing factor for M. gregaria strandings. The absence of shoaling animals in the Beagle Channel between 1997 and 2002 and the recent occurrence of swarms are coincident with their appearance in other locations in Patagonia. In consequence, we hypothesize that the factor influencing the formation of swarms must be acting at a regional scale. [ABSTRACT FROM AUTHOR]

We examined the isotopic signatures (δC, δN) of adult body feathers from southern giant petrels Macronectes giganteus collected at two breeding colonies in Antarctica (Potter Peninsula and Cape Geddes) and one in southern Patagonia (Observatorio Island), as well as in whole blood collected from adults of both sexes at each Antarctic colonies and from chicks at Potter Peninsula. As body feather moult is a continuous process in giant petrels, feathers provide an integrated annual signal of an adult's diets and foraging habitats. In contrast, the stable isotope values of adult and chick blood are reflective of their diets during the breeding season. We found that sex-specific dietary segregation in adults breeding in Antarctica was notable during the breeding season (blood samples) but absent when examined across the entire year (feather samples). In addition, blood stable isotope values differed between chicks and adults, indicating that adults provision their offspring with a relatively higher amount of penguin and seal prey that what they consume themselves. This finding confirms previous work that suggests that chicks are preferentially fed with prey of presumably higher nutritional value such as carrion. Finally, based on isotopic differences between major oceanographic zones in the Southern Ocean, our data indicate population-specific differences in foraging distribution, with Antarctic populations move seasonally between Antarctic and subantarctic zones, while Patagonian populations likely forage in subtropical waters and in continental shelf habitats year-round. [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]

This study investigates the movements of Magellanic Penguins Spheniscus magellanicus breeding on Isla Martillo during the early chick-rearing period. Foraging paths were reconstructed using GPS loggers that registered the penguins′ geographic position, water temperature and depth at regular intervals. The relationship between penguins′ movements and search strategies, tide and tidal currents were assessed. Mean trip duration was on average 14.7 ± 6.9 h (33% overnight), and the maximum distance reached was 24 ± 10 km. All penguins studied foraged to the east of the colony. We identified three phases based on the sinuosity and speed of the trajectory: transit, central and return. Foraging effort was higher during the central phase, followed by the transit phase, and lower in the return phase. Foraging success, measured as the percentage of time at the bottom during each phase, was also highest during the central phase. In all birds studied, the central phase of the foraging trip took place during ebb tide, and birds travelled to the foraging areas with flow tide running in the same direction of displacement. Our study suggests that penguins take advantage of tidal currents to facilitate their movements to and from the main foraging area, thereby reducing the energy expended. Moreover, we suggest that piscivorous diving birds may enhance their catch rate during ebb tide when fish are more concentrated near the channel bed. [ABSTRACT FROM AUTHOR]

Understanding the relationship between reproductive performance and food availability requires knowledge about many different variables, including such factors as the length of incubation shifts, provisioning rates and patterns, as well as how variability in these factors affects reproductive output. To examine some of the most important aspects of parental investment, we studied the provisioning behaviour and patterns of adult Southern Rockhopper Penguins Eudyptes chrysocome chrysocome breeding at Staten Island, Argentina. We investigated foraging trip duration, provisioning rates and chick survival using adult foraging patterns. Our results show that Rockhopper Penguins had clear sex-specific differences in their provisioning behaviour. Females provision chicks throughout chick rearing. By contrast, males provision chicks only during the crèche stage and at a slightly lower rate than females during this period. Foraging trips increased in length as the breeding season progressed. Rockhopper Penguins from Staten Island performed longer trips throughout the breeding season than do other species of Eudyptes at several other locations. Our results also show differences in parental investment between years that were related to differences in chick survival. We suggest that this was most likely to be related to female rather than male foraging behaviour as only females showed inter-annual differences in their provisioning rates. [ABSTRACT FROM AUTHOR]