André Chiaradia

Faced with unpredictable prey in dynamic ecosystems, seabirds have developed strategies to efficiently locate food, particularly during breeding when time and space are constrained. Using 13 yr of GPS data from 422 little penguins Eudyptula minor , we tested whether they rely on consistent foraging areas to reduce search times or respond to dynamic environmental cues. Our results suggest a combination of these strategies, depending on the spatial scale. Little penguins used only 32% of the potential foraging range, concentrating in shallow waters within 70 km and mostly east of their colony, as confirmed by our spatial density models. However, finer-scale analyses using kriging maps showed no recurring foraging hotspots over 13 yr, suggesting high inter-annual variability in prey availability. Despite this variability, penguins consistently spent more time in the most productive areas and also exploited more areas with favourable environmental conditions to access prey (thermocline, current, waves), even as these conditions shifted within and across breeding seasons. In years of poor conditions, they foraged farther from the colony, resulting in lower breeding success. These results emphasise the adaptability of little penguins to dynamic environmental conditions, but underscore the vulnerability of their foraging and breeding success to oceanographic variability in a climate-impacted ecosystem.

Phenotypic responses to climate affect individual fitness, but the extent to which this translates into effects on population dynamics remains poorly understood. We assemble 213 time series on phenotypes and population sizes of wild vertebrates globally and match them with local climate data. Our meta-analysis shows that morphological traits are mostly climate insensitive. However, phenology is earlier in warmer-than-average years, which contributes positively to population growth in most species. At lower latitudes, temperature has weaker effects on phenology but stronger direct negative effects on population growth, likely because these populations are less capable of tracking climate via plasticity. Variation in the phenology-mediated effect of temperature on population growth cannot be explained by latitude, generation time, migratory mode, or diet. This suggests that simple relationships between species characteristics and population responses to warming may not occur in nature. Instead, we may need to embrace ecological complexity by considering local-scale predictors that capture intra-specific variation.

Marine megafauna species are affected by a wide range of anthropogenic threats. To evaluate the risk of such threats, species’ vulnerability to each threat must first be determined. We build on the existing threats classification scheme and ranking system of the International Union for Conservation of Nature (IUCN) Red List of Threatened Species by assessing the vulnerability of 256 marine megafauna species to 23 at‐sea threats. The threats we considered included individual fishing gear types, climate‐change‐related subthreats not previously assessed, and threats associated with coastal impacts and maritime disturbances. Our ratings resulted in 70 species having high vulnerability ( v > 0.778 out of 1) to at least 1 threat, primarily drifting longlines, temperature extremes, or fixed gear. These 3 threats were also considered to have the most severe effects (i.e., steepest population declines). Overall, temperature extremes and plastics and other solid waste were rated as affecting the largest proportion of populations. Penguins, pinnipeds, and polar bears had the highest vulnerability to temperature extremes. Bony fishes had the highest vulnerability to drifting longlines and plastics and other solid waste; pelagic cetaceans to 4 maritime disturbance threats; elasmobranchs to 5 fishing threats; and flying birds to drifting longlines and 2 maritime disturbance threats. Sirenians and turtles had the highest vulnerability to at least one threat from all 4 categories. Despite not necessarily having severe effects for most taxonomic groups, temperature extremes were rated among the top threats for all taxa except bony fishes. The vulnerability scores we provide are an important first step in estimating the risk of threats to marine megafauna. Importantly, they help differentiate scope from severity, which is key to identifying threats that should be prioritized for mitigation.

Upon the rise in the intensity, duration and frequency of extreme events threatening life on Earth across land and ocean, there is a need to select ecologically significant areas for targeted management interventions. This study assesses the spatial overlap of multiple extreme events and calculates the cumulative magnitude faced across the Southern Hemisphere during the last decades, focusing on the 18 species of penguins as ecosystem sentinels that rely on terrestrial and marine environments. Our analysis identifies African, Snares, Emperor, Adélie and Galápagos as the penguin species experiencing the highest cumulative values of extreme events. Additionally, when looking at the trends, we identify that all penguin species, except the Galápagos penguin, will face a potential increase in extreme events if current trends are maintained. This study carries a crucial message in conservation, establishing a spatial framework that allows sounding the alert in ecologically important areas to reduce vulnerability during present and future extreme events.

Early environmental conditions experienced during juvenile growth are known to have marked effects on adult phenotypes in animal populations. Yet, the life‐history outcomes of variable growth strategies have rarely been investigated in wild populations. The aim of this study was to examine the natural variation of growth patterns displayed within a seabird population and assess their impact on juvenile survival, age at first reproduction, lifetime reproductive outputs (LRO) and longevity. Using a 26‐year study on the ecology of little penguins, we compiled over 2200 chick growth curves and defined 11 growth parameters classified by magnitude, form and rate. Although the growth curves formed a continuum according to these 11 growth parameters, non‐supervised statistical clustering showed that growth trajectories clustered into three main groups: fast, slow and light. Fast chicks ( n = 48%) attained the highest maximum mass in the shortest amount of time, whereas slow chicks ( n = 33%) stood out by a prolonged (+7 days, i.e. +13% in comparison to fast chicks) and irregular period of juvenile growth. Finally, light chicks ( n = 19%) reached low maximum and fledging masses (~−350 g; −37% and −36% of fast and slow chicks). We tested for the effects of chick growth parameters on subsequent annual vital rates estimated through capture–mark–recapture methods as well as longer term effects on life‐history outcomes using Markov chain models. Fast and slow individuals had the highest survival rates from hatching to yearling age (19% and 17%, respectively), while light chicks were at a disadvantage during this initial period (3% survival). Fast individuals reproduced 12% earlier (2.6 years old) than slow individuals, had 12.5%–88% greater longevity (up to 21 years old), and produced 1.2–3.8 times more eggs over their lifespan than slow and light individuals, respectively. Fast chicks reached maturity faster and produced more offspring during their lifetime without discernible negative effects to their longevity, highlighting possible silver spoon effects.

The recent Kunming-Montreal Global Biodiversity Framework (GBF) sets ambitious goals but no clear pathway for how zero loss of important biodiversity areas and halting human-induced extinction of threatened species will be achieved. We assembled a multi-taxa tracking dataset (11 million geopositions from 15,845 tracked individuals across 121 species) to provide a global assessment of space use of highly mobile marine megafauna, showing that 63% of the area that they cover is used 80% of the time as important migratory corridors or residence areas. The GBF 30% threshold (Target 3) will be insufficient for marine megafauna’s effective conservation, leaving important areas exposed to major anthropogenic threats. Coupling area protection with mitigation strategies (e.g., fishing regulation, wildlife-traffic separation) will be essential to reach international goals and conserve biodiversity.

Understanding the relative contributions of environmental, behavioural and social factors to reproductive success is crucial for predicting population dynamics of seabirds. However, these factors are often studied in isolation, limiting our ability to evaluate their combined influence. This study investigates how marine environmental variables, foraging behaviour and social factors (divorce), influence reproductive success in little penguins (Eudyptula minor) over 13 breeding seasons. By examining these factors together, we aimed to identify which is the most reliable predictor of population‐level reproductive success. We found that divorce rate was the most consistent predictor of reproductive success, with lower annual rates of divorce preceding the breeding season associated with higher hatching and fledging success. Foraging trip duration also influenced reproductive success, but in contrasting ways: Longer trips during egg incubation were linked with increased hatching success, while shorter trips after hatching led to higher fledging success. Marine environmental conditions had unexpected effects, with a lower Southern Oscillation Index (SOI) correlating with improved hatching and fledging success, in contrast to previous research, while sea surface temperature (SST) had no significant effect on reproductive success. This highlights the complexity of seabird breeding responses to large‐scale oceanographic indices, suggesting SOI and SST are generally less reliable measures to use as indicators of reproductive success. Our results suggest that divorce rate could serve as a valuable, noninvasive index of reproductive success in seabirds.

Passive acoustic monitoring is firmly established as an effective non-invasive technique for wildlife monitoring. The analysis of animal vocalizations recorded in their natural habitats is commonly used to monitor species occupancy, distribution mapping and community composition. The ability to distinguish between individual animals, however, remains underexplored and presents an exciting opportunity to study individual animal behavior and population demographics in more detail. In this work, we investigate bioacoustic individual-level recognition. In contrast to existing work, we focus on settings where only a subset of the existing population is known and labeled. This is crucial because wildlife populations are constantly changing so that solutions operating only within a known set of individuals are not realistically applicable in the wild. Using two novel datasets, we show that models initially trained to classify only known individuals can also be extended to detect new, previously unseen, individuals that are not part of the training set. We demonstrate that feature extractors pretrained on species classification can be successfully adapted for this task. Extending individual-level recognition to unknown individuals, so-called out-of-distribution classification, is a crucial step towards making individual recognition a realistic possibility in the wild. Highlights We show that features learned by models pretrained on bird species data can be transferred to individual classification tasks with minimal effort. We define and explore the out-of-distribution classification problem on individual animal vocalisations and address various subtleties and eco-logical use cases. We compile and contribute two additional datasets to facilitate further research on individual acoustic recognition.

Semiaquatic taxa, including humans, often swim at the air–water interface where they waste energy generating surface waves. For fully marine animals however, theory predicts the most cost-efficient depth-use pattern for migrating, air-breathing species that do not feed in transit is to travel at around 2 to 3 times the depth of their body diameter, to minimize the vertical distance traveled while avoiding wave drag close to the surface. This has rarely been examined, however, due to depth measurement resolution issues at the surface. Here, we present evidence for the use of this strategy in the wild to the nearest centimeter and document the switch to shallow swimming during naturally occurring long-distance migrations. Using high-resolution depth-accelerometry and video data for little penguins ( Eudyptula minor ) and loggerhead turtles ( Caretta caretta ), satellite-relayed data for green turtles ( Chelonia mydas ), and literature data for further sea turtle, penguin, and whale species, we show that near-surface swimming is likely used broadly across nonforaging diving animals to minimize the cost of transport.