THE MISSING LINK: UNRAVELING THE ECOLOGY AND BEHAVIOR OF LONG-LIVED PELAGIC SEABIRDS BEFORE THEY RECRUIT TO THE BREEDING POPULATION

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Niche segregation between immature and adult seabirds: Does progressive maturation play a role?

Publication . Campioni, Letizia; Granadeiro, José Pedro; Catry, Paulo

In long-lived species with slow maturation, prebreeders often represent a large percentage of the individuals alive at any moment, but their ecology is still understudied. Recent studies have found prebreeding seabirds to differ in their isotopic (and trophic) niche from adult breeders attending the same nesting colonies. These differences have been hypothesized to be linked to the less-developed foraging performance of younger and less-experienced immatures or perhaps to their inferior competitive abilities. Such differences from adults would wane as individuals mature (“the progressive ontogenetic shift hypothesis”) and could underpin the prolonged breeding deferral until adulthood displayed by those species. This study documents a marked difference in the nitrogen and carbon isotopic ratios measured in the whole blood of immatures and breeders in 2 pelagic seabird species (Cory’s shearwaters, Calonectris borealis, and black-browed albatrosses, Thalassarche melanophris) nesting in contrasting environments. However, blood isotopic values did not present a relationship with prebreeder age, suggesting no gradual ontogenetic shift from an immature toward an adult isotopic niche. Furthermore, isotopic signatures of sabbatical adults could not be separated from those of immatures attending the same colonies, but were clearly segregated from adult breeders. These results suggest that isotopic differentiation between immatures and breeders is mainly linked to a factor unrelated to previous experience and hence probably unrelated to a hypothetical gradual improvement of foraging competence or competitive abilities. Any ecological differentiation between breeders and nonbreeders is more likely related to the severity of the central-place foraging constraints and to the energetic requirements of reproduction (“the reproductive constraint hypothesis”).

2016Journal article

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Evaluating the influence of diet-related variables on breeding performance and home range behaviour of a top predator

Publication . Lourenço, Rui; Delgado, Maria del Mar; Campioni, Letizia; Korpimäki, Erkki; Penteriani, Vincenzo

Diet composition is linked to reproductive performance directly or indirectly by other life-history traits, including home range behaviour. The relationships between prey abundance, diet and individual fitness have often been explored. However, these relationships are complex and difficult to disentangle, especially in vertebrate top predators. Here, we present the results of a longterm study using multi-model inference procedures to elucidate the influence of diet-related variables on breeding parameters and home range behaviour of a top predator, the eagle owl Bubo bubo. Superpredation, diet diversity, rat biomass and rabbit mean weight were the most important variables when analysing reproductive parameters, suggesting that less diverse diets with greater rabbit biomass percentage may benefit reproductive performance, whereas rat biomass percentage is apparently associated with greater variation of breeding success. Earlier laying dates seem to be associated with the consumption, on average, of smaller rabbits. On the other hand, edge density was the most relevant factor determining the variation in home range behaviour, with individual characteristics, such as age and sex, also being important. Although the relative importance of the diet-related variables was generally low, mean weight of alternative prey, diet diversity and rabbit biomass also helped to explain home range parameters. In an optimal foraging context, centred on the abundance of the main prey species, our results suggest that when rabbits are less available eagle owls may increase home range size in order to obtain alternative prey, increasing at the same time their dietary diversity, which may also require higher movement speed.

2015Journal article

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Pattern of repeatability in the movement behaviour of a long-lived territorial species, the eagle owl

Publication . Campioni, Letizia; Delgado, Maria del Mar; Penteriani, Vincenzo

Observed movement patterns are the response of the interaction between environmental variables and the animal internal state. Therefore, even individuals of the same species experiencing similar environmental conditions can exhibit different behavioural responses, as these responses can be highly repeatable within individuals. Here, we investigated the nocturnal movement behaviour of a territorial species, by radiotracking 26 eagle owls Bubo bubo in order to analyze within and between individual variation with respect to movement parameters and route choice. Owls showed a considerable individual consistency in all movement parameters and made repeated use of similar routes while moving within fixed home ranges. Thus, movement parameters varied much less between repeated nightly trajectories than between different individuals. Furthermore, when we compared different individuals inhabiting the same territory in different years, within-group repeatability was low or non-significant suggesting that the spatial configuration of habitat does not always represents one of the main drivers in animal movement behaviour. Similarly, male individuals appeared to exhibit greater repeatability than females. The overall pattern of repeatability we found seems to identify such consistent movement behaviour not only as the expression of individual response to external/internal inputs but also as an additional trait to include in the broad definition of animal personality.

2016Journal article

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An ontogenetic perspective on migratory strategy of a long-lived pelagic seabird: Timings and destinations change progressively during maturation

Publication . Letizia, Campioni; Dias, Maria P.; Granadeiro, José Pedro; Catry, Paulo

The processes that drive the ontogeny of migratory strategies in long-lived animals with slow maturation remain enigmatic. While some short-lived migrants are known or believed to repeat the same migratory patterns throughout their lives, little is known on the time required for immature long-lived migrants to progressively acquire adult-like migratory behaviours, or which aspects take longer to refine during the maturation process. Here, we studied the ontogeny of long-distance migratory strategies and related patterns of spatial distribution in a long-lived seabird species during the annual cycle. To do so, we deployed light-level geolocators on 4- to 9-year-old immature Cory's shearwaters (Calonectris borealis) and on breeding adults. We revealed that migratory timings and destinations of young shearwaters progressively changed with age. The effect of ageing was remarkably evident on spring migratory performance and phenology. Birds gradually shortened the duration of the non-breeding period by advancing departure date and reducing travelling time, which resulted in a sequential arrival at the colony of the various age contingents. Ageing immatures gradually changed from a more exploratory strategy to a more conservative way of exploiting resources, reducing both their year-round spatial spread across oceanic domains and the total distance travelled. Immatures always performed a trans-equatorial migration to the Southern Hemisphere, contrasting with 17% of the adults which remained in the North Atlantic year-round. Finally, during the breeding season immatures were widely dispersed through the North Atlantic reducing their overlap with breeding adults. Our long-term study provides empirical support to the hypothesis that in long-lived species, the refinement of migratory behaviour and year-round spatial distribution is a progressive process mediated by age and experience, where life stage constraints and competition for resources may also play a role. The emerging pattern suggests that for some avian taxa, the ontogeny of migratory strategy is a prolonged, complex and dynamic process.

2020Journal article

Open access

Island-based Information Management System-GIS Data Centre as a key tool for spatial planning in the South Atlantic UK Overseas Territories

Publication . Marengo, Ilaria; Augé, Amélie A.; Campioni, Letizia; Blake, Denise; Cherrett, Samantha; Richardson, Andrew; Weber, Sam B.

Environmental data require fit-for-purpose data management systems and related spatial applications to be used effectively for management. Geographic Information Systems (GIS) have become a key tool to analyse and visualise spatial data with their increasing volume and variety. Well-designed data centres that combine a data management system with GIS, reduce costs and improve efficiency for spatial planning processes. Small or remote territories and islands such as the South Atlantic UK Overseas Territories (SAUKOT), with limited financial resources and capacity, face many challenges to develop such centres. In 2013 an island-based Information Management System (IMS)-GIS Data Centre was established in the SAUKOT. Until then, governments did not have the ability to use spatial planning effectively to manage their environments. The IMS-GIS Data Centre has been operating as: 1) repository of high-quality reference datasets to support decision making, 2) interactive data visualisation to share maps and information with stakeholders and 3) data portals to assist data discovery and sharing. This paper describes i) how the SAUKOT have built their own IMS-GIS Data Centres ii), how these Data Centres have provided effective and manageable solutions to support terrestrial and marine spatial planning processes and iii) the challenges the Data Centres are still facing. Thanks to relatively simple data management concepts and the use of open-source programs, the IMS-GIS Data Centre is transferable to other contexts sharing similar challenges to those faced by the SAUKOT

2020Journal article

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