**Abstract:**

Knowledge of the dispersion of seabirds during migration may provide information on predictable foraging areas, potential overlap with human activities and target conservation zones. The aim of this study was to analyze spatial distribution of Southern rockhoppers penguins -RP- (Eudyptes chrysocome chrysocome) and Magellanic penguins -MP- (Spheniscus magellanicus) during migration. We used geolocators (MK3 & MK4) to study migration movements of 10 RP breeding at Isla Pingüino (47°54'S; 65°43'W) and 20 MP breeding at Isla Quiroga (47°45'S, 65°53°W), Argentina, during 2019. We found that both male and female RP moved north, reaching the northern Uruguayan coast (32°30'), but southward, males traveled farther than females, reaching latitudes as far south as the Antarctic ocean. Males spend 33% of their time, while females only spend 7% of their time south of their breeding colony. Males dispersed more than females: latitudinal length (distance between northernmost and southernmost points) was 2250 km for females and 3250 km for males, and area according to the 50% Kernel density contour was threefold larger for males than for females. Males traveled farther offshore than females (190 km males vs. 145 km females) and spent more time in colder waters than females. Migration movements of MP have been described previously and were similar to RP female dispersion, but very different from RP males distribution. Latitudinal length for PM was 2100 km and they used warmer waters than RP. Area overlap (50% Kernel contour) between RP and MP was about 40-60% during April-May; 30% in June-July and no overlap in August. Female RP were exclusively responsible for these shared areas because male RP were farther south and farther offshore, even beyond the continental shelf. Different diets and breeding schedules might be responsible for the segregation between species. This study shows sexual segregation in RP at latitudinal and longitudinal levels, and an overlap between MP and female RP winter areas.

**Authors:**

melina barrionuevo¹, Annick Morgenthaler², Ana Millones², Nahuel Marchisio¹, Esteban Frere¹

¹UNPA-CONICET, ²UNPA

Winter ground segregation between two neighboring breeding penguins

**Abstract:**

In marine systems, resources are patchy and scattered over large spatial scales so that top predators like seabirds often rely on specific higher quality foraging zones (e.g. shelf edges, upwellings) that are predictable over years. Site fidelity is driven by predictable resource distributions in time and space. However, intrinsic factors related to the individual's physiology and life-history traits can contribute to consistent foraging behaviour and movement patterns. Using 11 years of continuous geolocation tracking data (fall 2008 to spring 2019), we investigated spatiotemporal consistency in non-breeding movements in a pelagic seabird population of black-legged kittiwake (Rissa tridactyla) breeding in the High Arctic (Svalbard). Our objective was to assess the relative importance of spatial versus temporal repeatability behind inter-annual movement consistency during winter. Most kittiwakes used pelagic regions of the western North Atlantic. Winter site fidelity was high both within and across individuals and at meso (100-1000 km) and macro scales (>1000 km), including over deep-water areas far from continental shelves. Spatial consistency in non-breeding movement was higher within than among individuals, suggesting that site fidelity might emerge from individuals' memory to return to locations with predictable resource availability. Consistency was also stronger in space than in time, suggesting that it was driven by consistent resource pulses that may vary in time more so than in space. Specialization for key wintering areas can indicate vulnerability to environmental perturbations, with winter survival and carry-over effects arising from winter conditions as potential drivers of population dynamics.

**Authors:**

Don-Jean Léandri-Breton¹, Kyle Elliott¹, Pierre Legagneux², Børge Moe³, Olivier Chastel⁴, Arnaud Tarroux⁵, Frédéric Angelier⁴, William Jouanneau⁴, Pierre Blévin⁶, Per Fauchald⁵, Sabrina Tartu⁴, Aurélie Goutte⁷, Vegard Sandøy Bråthen⁵

¹McGill University, ²Université Laval, ³Norwegian Institute for Nature Research (NINA), ⁴Centre d'Études Biologiques de Chizé (CEBC-CNRS) & Université de La Rochelle, ⁵Norwegian Institute for Nature Research, ⁶Akvaplan-NIVA, ⁷École Pratique des Hautes Études

Long-term tracking of an Arctic-breeding seabird indicates high fidelity for pelagic wintering areas

**Abstract:**

Advances in technology have revolutionized the tracking of marine organisms, but the at-sea distribution of small seabird species (i.e. <100 g) is still poorly known compared to their larger relatives. This study focuses on the foraging and at-sea distribution of an endemic species of storm-petrel that breed in the Azores archipelago: the summer breeding and endangered Monteiro's storm-petrel (Hydrobates monteiroi). We used miniature GPS loggers and conducted 59 deployments on incubating and chick-rearing petrels from Praia Islet, Azores, over three consecutive breeding seasons (2018--2020). We combined tracking data with information on static and dynamic habitat features to characterize the habitat preferences and to identify important at-sea foraging areas during the breeding season and developed spatial predictive models. Incubating birds had core foraging ranges that were further from the colony than chick-rearing birds, but there were no strong differences between birds tracked in different years. Bathymetric features (seafloor depth and distance from a seamount) were the most important determinants of foraging location in Monteiro's storm petrels, providing a range of predictable of at-sea priority use and conservation areas such as seamounts.

**Authors:**

Wiebke Schäfer¹, Gemma Carroll², Hannah Hereward³, Petra Quillfeldt¹, Verónica Neves⁴

¹Justus Liebig University Gießen, ²Environmental Defense Fund, ³Cardiff University, ⁴Azores University

Foraging and at-sea distribution of a vulnerable and endemic storm-petrel

**Abstract:**

Sexual competition is increasingly recognized as an important selective pressure driving species distributions. However, few studies have investigated the relative importance of interpopulation versus intrapopulation competition in relation to habitat availability and selection. To explain spatial segregation between sexes that often occurs in seabirds, two hypotheses are commonly used. The 'competitive exclusion' hypothesis states that dominant individuals should exclude subordinate individuals through direct competition, whereas the 'niche divergence' hypothesis states that segregation occurs due to past competition and habitat specialization. We tested these hypotheses in two populations of an extreme wide-ranging and sexually dimorphic seabird, investigating the relative role of intrapopulation and interpopulation competition in influencing sex­ specific distribution and habitat preferences. Using GPS loggers, we tracked 192 wandering albatrosses Diomedea exulans during four consecutive years (2016-2019), from two neighbouring populations in the Southern Ocean (Prince Edward and Crozet archipelagos). We simulated pseudo-tracks to create a null spatial distribution and used Kernel Density Estimates (KDE) and Resource Selection Functions (RSF) to distinguish the relative importance of within versus between population competition. Kernel Density Estimates showed that only intrapopulation sexual segregation was significant for each monitoring year, and that tracks between the two colonies resulted in greater overlap than expected from the null distribution, especially for the females. RSF confirmed these results and highlighted key at­sea foraging areas, even if the estimated of at-sea densities were extremely low. These differences in selected areas between sites and sexes were, however, associated with high interannual variability in habitat preferences, with no clear specific preferences per site and sex. Our results suggest that even with low at-sea population densities, historic intrapopulation competition in wide ­ranging seabirds may have led to sexual dimorphism and niche specialization, favouring the 'niche divergence' hypothesis. In this study, we provide a protocol to study competition within as well as between populations of central place foragers. This is relevant for understanding their distribution patterns and population regulation, which could potentially improve management of threatened populations.

**Authors:**

Florian Orgeret¹, Ryan Reisinger², Tegan Carpenter-Kling¹, Alexandre Corbeau³, Danielle Keys¹, Charles-André Bost⁴, Henri Weimerskirch⁴, Pierre Pistorius¹

¹Nelson Mandela University, ²Institute of Marine Sciences, University of California Santa Cruz, ³Centre d'Etudes Biologiques de Chize, ⁴Centre d?Etudes Biologiques de Chizé

Spatial segregation in a sexually dimorphic central place forager: Competitive exclusion or niche divergence?

**Abstract:**

Timing of breeding is a trait shaped to optimize resource use while avoiding adverse conditions. It has been suggested that, in some seabird species, allochronic breeding between summer and winter populations may drive genetic isolation to different extents. However, little is known about the connectivity and ecological segregation between populations fuelling this evolutionary process. This study describes the phenology, connectivity, differences in spatial use, habitat selection, daily activity patterns, and isotopic niche of allochronic populations of the Cape Verde storm-petrel Hydrobates jabejabe breeding in Cima Islet Cabo Verde. We ringed breeders and birds in mist-nets for doing analyses on the populations connectivity, deployed GPS and GLS loggers for studying spatial niche in the breeding and non-breeding season respectively, and for studying the daily activity niche through wet-dry data, and took blood/feather samples for studying the isotopic niche. Summer (hot) population bred from February to August, while the winter (cool) population did it from September to January, showing a very low exchange rate of breeders between them and only a few inter-seasonal breeders. Both populations showed a high spatial overlap in their foraging areas during both, the breeding and the non-breeding period, respectively. Both populations fitted their timing of breeding to pulses of oceanic productivity around Cabo Verde while avoiding rainfalls, suggesting inter-seasonal breeders may be disfavoured. Oceanic productivity was higher for the hot population during the breeding and non-breeding areas and spent a higher proportion of time resting on the water during the non-breeding period. Overall, our results showed two populations well-differentiated in their annual phenological events and very low connectivity among them, but with little ecological segregation. Pulses of oceanic productivity may be driving allochrony but does seem not imply an speciation process.

**Authors:**

Fernando Medrano¹, Teresa Militão¹, Ivandra Gomes², Mariona Sarda-Serra¹, Monica de la Fuente¹, Herculano Dinis², Jacob González-Solis¹

¹Institut de Recerca de la Biodiversitat (IRBio) i Departament de Biologia Evolutiva, Ecologia i Cièn, ²Associação Projecto Vitó, São Filipe, Ilha do Fogo, Cabo Verde

Phenological divergence, population connectivity and ecological segregation between two allochronic seabird populations

**Abstract:**

Sabine's gulls undertake the longest migration of any gull, a trans-equatorial journey between Arctic breeding and southern hemisphere wintering areas. For such long-distance migrants, quantifying within- and between-individual variation in migratory strategy is key towards understanding resilience to environmental variability encountered over migration. We tracked 22 birds on 32 migrations from the Canadian Arctic to evaluate strategies and quantify flexibility among individuals and years. All birds undertook extended stopovers in a geographically-restricted staging area halfway through migration in the California Current System in both directions. Individuals were otherwise flexible in most aspects of migration but were repeatable in arrival date and duration of the southbound staging phase. Routes taken during southbound migration and overlap in overwintering areas were significantly larger within the same year than among years. Overall, birds showed high individual flexibility in migratory strategies but made similar decisions to one another in the same years. Every year, all birds showed repeatable, consistent reliance on the staging grounds as a key stopover site in both directions. This suggests Sabine?s gulls adjust to environmental change in many aspects of their migration but may be vulnerable to climate change and other anthropogenic influences during critical stages of the journey.

**Authors:**

Sarah Gutowsky¹, Mark Mallory¹, Shanti Davis², Mark Maftei²

¹Acadia University, ²High Arctic Gull Research Group

Flexibility in migratory strategy contrasts with reliance on restricted staging and overwintering grounds for Sabine's gulls from the Canadian High Arctic

**Abstract:**

Wildlife are exposed to many simultaneous stressors, the effects of which are amplified along with increasing human activity globally. In Arctic regions, more severe weather systems, increasing air and ocean temperatures, and exposure to environmental contaminants all represent stressors occurring simultaneously. While seabirds are expected to be at risk of adverse effects from these individual stressors, few studies have researched their combined impacts on breeding behaviour and reproductive success. Therefore, we examined the interactive effects of air temperature, wind speed and mercury (Hg) contamination (via first-laid egg) on laying phenology and incubation behaviour in female common eiders (Somateria mollissima, Mitiq) nesting at Canada's largest Arctic breeding colony (East Bay (Mitivik) Island) from 2016-2019. Exposure to higher pre-breeding air temperatures resulted in females with higher egg Hg concentrations laying earlier than those with lower Hg levels. Furthermore, examination of 190 days of incubation behaviour from 61 eiders across two years showed that nest-level air temperature exposure had the most significant effect on incubation behaviour, with higher air temperatures correlating with more interruptions. Importantly, interactive exposure to higher air temperatures and higher Hg concentrations was related to increased incubation interruptions at a greater effect level than just air temperature alone. Although previous research has shown that warmer spring temperatures may relieve constraints on lower quality females, giving them more time to gain in body condition to successfully lay, our results suggest these females face stronger cumulative costs during incubation in warmer years, especially if they have higher contaminant loads. Our study highlights the potential interactive mechanisms, driven by human-induced environmental changes, that may impact overall individual and colony reproductive success in Arctic seabirds, especially within the context of increasing environmental and predator pressures.

**Authors:**

Reyd Smith¹, Saya Albonaimi¹, Holly Hennin², Grant Gilchrist², Jérôme Fort³, Kyle Parkinson¹, Jennifer Provencher², Oliver Love¹

¹University of Windsor, ²Environment and Climate Change Canada, ³Littoral, Environnement et Sociétés (LIENSs)

Cumulative effects of environmental conditions and mercury exposure on laying phenology and incubation behaviour

**Abstract:**

Human activity may significantly affect animal abundance, distribution and behaviour. In several regions of the world, human productive activities generally show a marked difference in intensity between week-days and week-end. For instance, fishing activity, which is known to affect seabird behaviour, may show lower intensity on the week-end. To assess whether such fishing schedule affects seabird activity, we analyzed daily foraging behaviour of three seabird species breeding in the Adriatic sea, an over-exploited Mediterranean region where trawlers activity is interdicted during week-end. We relied on GPS-data from two seagull species, the Mediterranean gull (Ichthyaetus melanocephalus) and the yellow-legged gull (Larus michahellis), which can forage both on land and at sea, and from the pelagic Scopoli´s shearwater (Calonectris diomedea). All birds were GPS-tagged during the breeding period. The daily proportion of GPS positions at-sea over all recorded positions was significantly lower on week-end compared to week-days in both seagull species. Location at sea were such rare on the week-end as to suggest a possible transfer of information at the colony on the current distribution of food resources. Moreover, we found individual differences in the reaction to the "week-end effect". On top of this, we found that the probability of foraging at sea for gulls was higher when rain was absent or light and wave motion was slight. As for seagulls, also the pelagic Scopoli´s shearwater changed foraging behaviour on week-end, showing a significant lower proportion of those behaviours which are known for other tubenose species to be related to foraging in association with fishing vessels (sinuous movements and floating) and a higher proportion of relocation movements compared to week-days. Overall, our results highlight the marked behavioural plasticity of seabird species and stress the complexity of relationship between seabirds and commercial fishing activity.

**Authors:**

Jacopo Cecere¹, Simona Imperio¹, Simone Pirrello¹, Riccardo Nardelli¹, Alessandro Andreotti¹, Fernando Spina¹, Lorenzo Serra¹

¹ISPRA

Seabird foraging behaviour changes on the week-end according to scheduled fishery activity in the Adriatic Sea

**Abstract:**

Temporal patterns of animal activity can be affected by both abiotic (e.g. temperature, wind) and biotic factors (e.g. spatial and temporal distribution of prey species, inter-specific competition). Despite the analysis of activity rhythms can reveal how species adapt to environmental changes, little is known about daily activity patterns in seabirds. We investigated the diel activity pattern of 196 Scopoli's shearwaters (Calonectris diomedea) fitted with GPS-loggers from 3 different Mediterranean breeding sites, namely Linosa island (Sicily Channel), Tremiti Archipelago (Adriatic Sea) and La Maddalena Archipelago (Tyrrhenian Sea), from 2008 to 2018. During both incubation and chick-rearing periods breeding shearwaters are central-place foragers, performing self-provisioning foraging trips that last up to 18 days, alternated, during the latter period, to short chick-provisioning foraging trips. Behavioural modes, assessed through EMbC, revealed that both intensive and extensive search were evenly distributed during the daily cycle, while floating behaviour was concentrated during the night and the central hours of the day, and relocation was most frequent in the few hours following dawn and preceding dusk. Accordingly, flying activity computed as the average speed between two GPS positions showed a bimodal pattern for all the 3 colonies. Yet, the temporal pattern of flying activity was significantly different among colonies, with birds from Linosa showing narrower peaks of activity. The observed differences cannot be explained by different twilight times among colonies, and are likely linked to fishery activity and/or variation in meteorological variables, the latter also explaining the differences between sexes. Indeed, as the breeding period proceeds, females show higher flying activity, likely due to their lower wing loading and the consequent better ability in exploiting winds. Differences were also found between short- and long-lasting foraging trips, suggesting that modulation of the daily activity in seabirds may represent a behavioural adaptation to a combination of food availability and environmental conditions.

**Authors:**

Simona Imperio¹, Davide Dominoni², Federico De Pascalis³, Carlo Catoni⁴, Giorgia Gaibani⁵, Diego Rubolini³, Jacopo Cecere¹

¹ISPRA, ²University of Glasgow, ³University of Milan, ⁴Ornis Italica, ⁵LIPU

Spatial variation of daily activity patterns in the Scopoli's shearwater

**Abstract:**

While most bird species exhibit bi-parental care, with both parents adjusting theirs workload in respect to each other, still little is known of how this adjustment is achieved. Vocal communication has recently been pointed out as a potential mechanism of such parental care adjustment in songbirds, but remains poorly studied in seabirds. Here we examine the role of partners' vocal interactions in the parental care of a monogamous seabird, the Little Auk (Alle alle). Little Auks' breeding partners share their parental duties equally and in a coordinated manner; during the whole breeding period they frequently meet at the nest and vocalize together, which makes it a perfect system for studying the role of vocal communication in parental coordination. We investigate whether the temporal and acoustical structure of the partners' vocal interaction in the nest predict its output (relief or not of the incubating partner), and whether they are related to the duration of the previous and subsequent incubation bouts. Our results are the first attempt to answer such questions in seabirds, and we believe they will constitute a solid background for both examining the mechanisms regulating parental care and the importance of vocal communication between avian breeding partners.

**Authors:**

Marion Devogel¹, Antoine Grissot¹, Dorota Kidawa¹, Marcelo Araya-Salas², Katarzyna Wojczulanis-Jakubas¹

¹University of Gdansk, ²Universidad de San josé

Should I stay or should I go: Is vocal communication a key to coordinated parental care in a monogamous seabird, the Little Auk (Alle alle) ?

**Abstract:**

Bird species that practice obligate siblicide (originally named cainism) lay two eggs, but almost never raise more than one offspring, because the first hatched chick kills the second soon after hatching. The adaptive value of this behavior has puzzled naturalists since the times of Aristoteles. There is still no general satisfactory explanation for the evolution of this behavior, although various mechanisms have been proposed. According to the "Insurance hypothesis", by laying an extra egg, the parents may be able to protect themselves from raising an under-sized brood (or no young at all) in a given season; specifically, they are buffered against complete reproductive failure that may arise from early mortality of eggs and chicks. This study aimed to test the "Insurance hypothesis" for the laying of a second egg. We experimentally tested this hypothesis in pairs of adjacent 2-egg clutches in a colony of breeding brown boobies (Sula leucogaster), by removing one egg from experimental clutches while holding unmanipulated clutches as controls. As predicted, the experimental nests on average produced fewer hatchlings and a smaller proportion of them had a chick at 10days, i.e. 34% and 61% for experimentals and controls, respectively. This difference was almost three-fold difference at 60 days post-hatching, i.e. 12% of experimental nests vs 31% of control nests produced a fledgling. The insurance benefit of the second egg seemed to be most significant during the incubation phase, or for fertilization of the eggs, because there was no difference in success between parents that had hatched one versus two eggs among unmanipulated clutches. However, among nests that were deserted during chick rearing, parents that had hatched two eggs tended to remain longer than parents that had hatched only one egg. We conclude that the most important insurance benefit of a second egg is against egg hatching failure.

**Authors:**

Lars Hillström¹, Francisco Sanchez Tortosa²

¹University of Gävle, ²University of Cordoba

Function of obligate siblicide in the Brown booby, Sula leucogaster: an experimental test of the Insurance hypothesis.

**Abstract:**

Seabirds are one of the most threatened groups of birds globally, and many seabird populations are experiencing severe declines. This is true in the Atlantic ocean where many seabird populations have undergone widespread breeding failures, highlighting the need for conservation action in this region. Identifying sites suitable for protection is one approach for seabird conservation. While breeding colonies are generally well protected across European countries, there remains a gap for important non-breeding and foraging sites. We analysed all available seabird tracking data for the Northeast Atlantic (www.seabirdtracking.org). This totaled 2,188 tracked individuals from 23 species, from 105 colonies across 11 countries in both the North and South Atlantic. We followed standardized methods of identifying marine hotspots based on tracking data and information on population abundance, in collaboration with more than 60 from researchers and data holders. We identified a seabird diversity and abundance hotspot in the middle of the North Atlantic, which was previously unknown. This area is an important pelagic foraging ground for at least 22 seabird species, including 7 globally or regionally threatened species. The area is particular important for migratory seabird species, with the highest concentrations occurring during the winter period (October-March) with up to 5 million individuals using the area. The spring summer period (April-September) saw the highest number of species using the area (n=21) and also saw large numbers of birds (up to 3.3 million), many as a stopover during trans-equatorial migrations. Protection of this 'seabird cafe' comes under the remit of the Regional Seas Convention for the North East Atlantic (OSPAR), who are considering the site as a marine protected area. Protection of this site would require collaboration between all OSPAR parties, as well as competent authorities operating in the region.

**Authors:**

Tammy Davies¹, Ana Carneiro¹, Maria Dias¹

¹BirdLife International

Underline digital video library

Winter ground segregation between two neighboring breeding penguins

Long-term tracking of an Arctic-breeding seabird indicates high fidelity for pelagic wintering areas

Foraging and at-sea distribution of a vulnerable and endemic storm-petrel

Spatial segregation in a sexually dimorphic central place forager: Competitive exclusion or niche divergence?

Phenological divergence, population connectivity and ecological segregation between two allochronic seabird populations

Flexibility in migratory strategy contrasts with reliance on restricted staging and overwintering grounds for Sabine's gulls from the Canadian High Arctic

Cumulative effects of environmental conditions and mercury exposure on laying phenology and incubation behaviour

Seabird foraging behaviour changes on the week-end according to scheduled fishery activity in the Adriatic Sea

Spatial variation of daily activity patterns in the Scopoli's shearwater

Should I stay or should I go: Is vocal communication a key to coordinated parental care in a monogamous seabird, the Little Auk (Alle alle) ?

Function of obligate siblicide in the Brown booby, Sula leucogaster: an experimental test of the Insurance hypothesis.

Identification and protection of a seabird cafe in the NE Atlantic

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