Seabirds are undergoing drastic declines globally and spend the non-breeding season at sea, making it challenging to study the drivers of their survival. Harsh weather and changes in climate ...conditions can have large impacts on seabird population dynamics through increased mortality. The intensity and persistence of extreme events are forecasted to increase with global warming. As shared conditions can induce population synchrony, multi-population studies of key demographic parameters are imperative to explore the influence of climate change. We used long-term mark-recapture data and position data to determine non-breeding stop-over areas of 5 Atlantic puffin (
Fratercula arctica
) populations over a latitudinal gradient in the Northeast Atlantic (56°11’-70°23’N). We investigated synchrony in adult survival in relation to shared stop-over areas. We quantified effects of extreme extra-tropical cyclones (ETCs) specific to populations’ stop-over areas and the North Atlantic Oscillation on adult survival. Populations with overlapping stop-over areas exhibited temporal synchrony in survival rates. Winter ETCs negatively influenced survival in 1 population, which was the one most exposed to extreme weather, but did not directly influence adult survival in the other 4 populations. Synchrony among populations with shared stop-over areas highlights the importance of these areas for adult survival, a key life-history rate. However, extreme weather was not identified as a driving factor for the majority of study populations. This suggests other factors in these areas, likely related to bottom-up trophic interactions, as environmental drivers of synchrony in the survival of Atlantic puffins.
Bird migration is commonly defined as a seasonal movement between breeding and non-breeding grounds. It generally involves relatively straight and directed large-scale movements, with a latitudinal ...change, and specific daily activity patterns comprising less or no foraging and more traveling time. Our main objective was to describe how this general definition applies to seabirds. We investigated migration characteristics of 6 pelagic seabird species (little auk
Alle alle
, Atlantic puffin
Fratercula arctica
, common guillemot
Uria aalge,
Brünnich’s guillemot
U
.
lomvia,
black-legged kittiwake
Rissa tridactyla
and northern fulmars
Fulmarus glacialis
). We analysed an extensive geolocator positional and saltwater immersion dataset from 29 colonies in the North-East Atlantic and across several years (2008-2019). We used a novel method to identify active migration periods based on segmentation of time series of track characteristics (latitude, longitude, net-squared displacement). Additionally, we used the saltwater immersion data of geolocators to infer bird activity. We found that the 6 species had, on average, 3 to 4 migration periods and 2 to 3 distinct stationary areas during the non-breeding season. On average, seabirds spent the winter at lower latitudes than their breeding colonies and followed specific migration routes rather than non-directionally dispersing from their colonies. Differences in daily activity patterns were small between migratory and stationary periods, suggesting that all species continued to forage and rest while migrating, engaging in a ‘fly-and-forage’ migratory strategy. We thereby demonstrate the importance of habitats visited during seabird migrations as those that are not just flown over, but which may be important for re-fuelling.
Tracking data of marine predators are increasingly used in marine spatial management. We developed a spatial data set with estimates of the monthly distribution of 6 pelagic seabird species breeding ...in the Northeast Atlantic. The data set was based on year-round global location sensor (GLS) tracking data of 2356 adult seabirds from 2006-2019 from a network of seabird colonies, data describing the physical environment and data on seabird population sizes. Tracking and environmental data were combined in monthly species distribution models (SDMs). Cross-validations were used to assess the transferability of models between years and breeding locations. The analyses showed that birds from colonies close to each other (<500 km apart) used the same nonbreeding habitats, while birds from distant colonies (>1000 km) used colony-specific and, in many cases, non-overlapping habitats. Based on these results, the SDM from the nearest model colony was used to predict the distribution of all seabird colonies lying within a species-specific cut-off distance (400-500 km). Uncertainties in the predictions were estimated by cluster bootstrap sampling. The resulting data set consisted of 4692 map layers, each layer predicting the densities of birds from a given species, colony and month across the North Atlantic. This data set represents the annual distribution of 23.5 million adult pelagic seabirds, or 87% of the Northeast Atlantic breeding population of the study species. We show how the data set can be used in population and spatial management applications, including the detection of population-specific nonbreeding habitats and identifying populations influenced by marine protected areas.
Species breeding at high latitudes face a significant challenge of surviving the winter. Such conditions are particularly severe for diurnal marine endotherms such as seabirds. A critical question is ...therefore what behavioural strategies such species adopt to maximise survival probability. We tested 3 hypotheses: (1) they migrate to lower latitudes to exploit longer day length (‘sun-chasing’), (2) they forage at night (‘night-feeding’), or (3) they target high-quality food patches to minimise foraging time (‘feasting’). We studied the winter migration and foraging strategies of European shags
Phalacrocorax aristotelis
from 6 colonies across a latitudinal gradient from temperate regions to north of the Arctic Circle using geolocators deployed over 11 winters. We found evidence for ‘sun-chasing’, whereby average southerly movements were greatest from colonies at higher latitudes. However, a proportion of individuals from higher latitudes remained resident in winter and, in the absence of daylight, they foraged during twilight and only very occasionally during the night. At lower latitudes, there was little evidence that individuals migrated south, nocturnal feeding was absent, and twilight feeding was infrequent, suggesting that there was sufficient daylight in winter. There was no evidence that winter foraging time was lowest at higher latitudes, as predicted by the ‘feasting’ hypothesis. Our results suggest that shags adopt different behavioural strategies to survive the winter across their latitudinal range, dictated by the differing light constraints. Our study highlights the value of multi-colony studies in testing key hypotheses to explain population persistence in seabird species that occur over large latitudinal ranges.
Global climate change requires species to adapt to increasing environmental variability, rising air and ocean temperatures and many other effects, including temperature associated phenological ...shifts. Species may adapt to such rapid changes by microevolutionary processes and/or phenotypic plasticity. The speed of microevolutionary adaptation may critically be enhanced by between-individual differences in phenotypic plasticity. However, such between-individual differences have rarely been shown, especially for long-lived and migratory species that appear particularly vulnerable to phenological shifts. Southern rockhopper penguins Eudyptes chrysocome chrysocome are migratory, long-lived seabirds with a ‘vulnerable’ conservation status. We studied clutch initiation date (CID) and investment into egg mass in individually marked females in response to broad-scale and local climate variables across 7 yr. We thereby distinguished within-individual and between-individual variation and tested the existence of between-individual differences in the expression of phenotypic plasticity. Because of both within-individual and between-individual variation, CID was significantly advanced under high Southern Annular Mode (SAM), reflecting colder environmental conditions and higher food availability. Total clutch mass increased under low local sea surface temperatures (significant within-individual effect) but was mostly accounted for by female identity. Intra-clutch egg-mass dimorphism was not affected by environmental variables at all. We found no indication of between-individual differences in phenotypic plasticity and overall, the expression of phenotypic plasticity appeared to be limited. This raises the question whether between-individual differences in phenotypic plasticity exist in other long-lived species and whether rockhopper penguins show sufficient phenotypic plasticity to adapt to predicted climate changes.
The Royal Penguin Eudyptes schlegeli breeds only on Australia's Macquarie Island and its nearby islets, about 1 200 km southwest of New Zealand. Vagrant Royal Penguins have been reported elsewhere in ...Australia, New Zealand and Antarctica. Reports of Royal Penguins from other subantarctic islands, including Heard, Prince Edward and Marion Islands, South Georgia and the Falkland Islands are controversial, as these penguins could also be aberrant Macaroni Penguins E. chrysolophus, and species determination can be difficult because of high variation in facial colour in both species. We discuss here the recent sighting of an apparent immature Royal Penguin on New Island, Falkland Islands. A simultaneously visiting adult male Macaroni Penguin allowed a size comparison between the two individuals. This could be the first documented sighting of a vagrant Royal Penguin in the Neotropical region.
Ecological niche theory predicts sympatric species to show segregation in their spatio‐temporal habitat utilization or diet as a strategy to avoid competition. Similarly, within species individuals ...may specialize on specific dietary resources or foraging habitats. Such individual specialization seems to occur particularly in environments with predictable resource distribution and limited environmental variability. Still, little is known about how seasonal environmental variability affects segregation of resources within species and between closely related sympatric species.
The aim of the study was to investigate the foraging behaviour of three closely related and sympatrically breeding fulmarine petrels (Antarctic petrels Thalassoica antarctica, cape petrels Daption capense and southern fulmars Fulmarus glacialoides) in a seasonally highly variable environment (Prydz Bay, Antarctica) with the aim of assessing inter‐ and intraspecific overlap in utilized habitat, timing of foraging and diet and to identify foraging habitat preferences.
We used GPS loggers with wet/dry sensors to assess spatial habitat utilization over the entire breeding season. Trophic overlap was investigated using stable isotope analysis based on blood, feathers and egg membranes. Foraging locations were identified using wet/dry data recorded by the GPS loggers and expectation‐maximization binary clustering. Foraging habitat preferences were modelled using generalized additive models and model cross‐validation.
During incubation and chick‐rearing, the utilization distribution of all three species overlapped significantly and species also overlapped in the timing of foraging during the day—partly during incubation and completely during chick‐rearing. Isotopic centroids showed no significant segregation between at least two species for feathers and egg membranes, and among all species during incubation (reflected by blood). Within species, there was no individual specialization in foraging sites or environmental space. Furthermore, no single environmental covariate predicted foraging activity along trip trajectories. Instead, best‐explanatory environmental covariates varied within and between individuals even across short temporal scales, reflecting a highly generalist behaviour of birds.
Our results may be explained by optimal foraging theory. In the highly productive but spatio‐temporally variable Antarctic environment, being a generalist may be key to finding mobile prey—even though this increases the potential for competition within and among sympatric species.
This article shows a striking case of closely related and sympatrically breeding species overlapping in their resource use across multiple dimensions. The very unusual results are best explained by high food availability in combination with spatio‐temporal environmental variability and mobile prey fields, requiring predators to respond opportunistically and show generalist foraging behaviour.
Recognition requires the existence of distinct cues and the ability to detect and discriminate between these signals. Using gas chromatography–mass spectrometry, we investigated the chemical ...composition of 143 anal scent gland secretions from 84 individually known spotted hyaenas,
Crocuta crocuta, in three clans in the Serengeti National Park, Tanzania. In total, 252 volatile compounds were detected. Comparison of the chemical composition of individual scent profiles by calculating the Bray–Curtis similarity index and using an analysis of similarities revealed that scent profiles varied significantly between individuals but also changed in composition over time. There was no difference in complexity, in terms of the number of different compounds, between male and female scent or between scent from high- and low-ranking females. Scent profiles of closely related females were as similar as profiles of unrelated females. Although there was no evidence of rank-related changes in profiles across the entire female social hierarchy, the profiles of high-ranking females differed significantly from those of low-ranking females, suggesting the presence of an olfactory badge of status. Behaviourally, adult females responded to scent deposited on vegetation by other females significantly faster and more often, and were more likely to anoint themselves with that scent, as the social rank of the female who had deposited the scent increased. These results suggest that spotted hyaena scent carries both an olfactory badge of status and individually distinct cues that are likely to be useful in the maintenance of a social network within their fission–fusion society.
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