Habitat selection and spatio-temporal dynamics of colonies of two larid species : the black-headed gull and the slender-billed gull

La dynamique des populations vise à étudier les processus qui déterminent les fluctuations spatio-temporelles des effectifs d’organismes vivants. Ma thèse vise à caractériser les relations entre trois niveaux d’organisation des populations d’oiseaux coloniaux, l’individu, la colonie et la méta-colonie, et à étudier l’influence de l’environnement physique et social sur cette organisation. A cette fin, je me suis concentrée sur deux espèces de laridés coloniaux aux dynamiques de populations contrastées: la mouette rieuse, Chroicocephalus ridibundus, et le goéland railleur, Chroicocephalus genei. J’ai décrit, dans un premier temps, la dynamique spatio-temporelle des colonies de goélands railleurs en France, dont la répartition tend à s’étendre le long de la côte Méditerranéenne. Malgré cette expansion, les individus nés en France restent fidèles à leur région natale, mais leur âge et leur sexe modulent leur recrutement et leur comportement de dispersion. J’ai affiné ce premier travail en montrant que la condition corporelle des poussins, paramètre majeur du recrutement, est modulée par la taille des colonies, sa date d’installation et la stratégie d’alimentation des parents. Mes travaux ont de plus permis de montrer l’existence de groupes sociaux chez le goéland railleur, dont la stabilité est modulée par le succès de reproduction de la colonie. Ainsi, le degré de relations entre les individus d’une colonie est modulé par les caractéristiques intrinsèques de la colonie et son contexte environnemental. J’ai en particulier montré, chez la mouette rieuse, que la persistance des colonies dépend du succès de reproduction local, mais que la colonisation de nouveaux sites dépend plutôt du succès de reproduction dans les colonies avoisinantes. Mes travaux montrent ainsi que l’ensemble des niveaux d’organisation des populations d’oiseaux coloniaux, de l’individu à la méta-colonie, doivent être étudiés à travers de nouvelles approches intégratives qui représentent des challenges conceptuels, méthodologiques et techniques à l’interface entre dynamique des populations et étude des réseaux sociaux.Population dynamics addresses the processes that underpin the spatio-temporal fluctuations of organism counts. My PhD dissertation aims at characterizing the connections between three organization levels in colonial bird populations, the individual, the colony, and the meta-colony, and at investigating the influence of the physical and social environments on this organization. To this aim, I focused on two colonial larid species that exhibit contrasted population dynamics: the black headed gull, Chroicocephalus ridibundus, and the slender-billed gull, Chroicocephalus genei. I first described the population dynamics of french slender-billed gull colonies, which are currently spreading along the Mediterranean coast. In spite of this expansion, individuals born in France return to their natal area to breed, but their age and sex modulate their recruitment and dispersal behaviours. I added-up to this first results by showing that nestling body condition, a major factor for recruitment, is affected by colony size, arrival date and parental foraging strategy. I further showed that slender-billed gulls gather into social groups whose stability is modulated by colony breeding success. The strength of inter-individual relationships within a colony is thus modulated by its intrinsic properties and its environmental context. Furthermore, I showed that, in black-headed gulls, colony persistance varies with local breeding success while colonization of new sites is mainly related to breeding success in neighbouring colonies. I conclude overall that the multiple organization levels of colonial bird populations, from the individual to the meta-colony, should be studied within integrative frameworks that represent novel conceptual, methodological and technical challenges at the crossroad between population dynamics and the study of social networks

A synthesis of recent tools and perspectives in migratory connectivity studies

Abstract Migration movements connect breeding and non-breeding bird populations over the year. Such links, referred to as migratory connectivity, have important implications for migratory population dynamics as they dictate the consequences of localised events for the whole population network. This calls for concerted efforts to understand migration processes for large-scale conservation. Over the last 20 years, the toolbox to investigate connectivity patterns has expanded and studies now consider migratory connectivity over a broader range of species and contexts. Here, we summarise recent developments in analysing migratory connectivity, focusing on strategies and challenges to pooling various types of data to both optimise and broaden the scope of connectivity studies. We find that the different approaches used to investigate migratory connectivity still have complementary strengths and weaknesses, whether in terms of cost, spatial and temporal resolution, or challenges in obtaining large sample sizes or connectivity estimates. Certain recent developments offer particularly promising prospects: robust quantitative models for banding data, improved precision of geolocators and accessibility of telemetry tracking systems, and increasingly precise probabilistic assignments based on genomic markers or large-scale isoscapes. In parallel, studies have proposed various ways to combine the information of different datasets, from simply comparing the connectivity patterns they draw to formally integrating their analyses. Such data combinations have proven to be more accurate in estimating connectivity patterns, particularly for integrated approaches that offer promising flexibility. Given the diversity of available tools, future studies would benefit from a rigorous comparative evaluation of the different methodologies to guide data collection to complete migration atlases: where and when should data be collected during the migratory cycle to best describe connectivity patterns? Which data are most favourable to combine, and under what conditions? Are there methods for combining data that are better than others? Can combination methods be improved by adjusting the contribution of the various data in the models? How can we fully integrate connectivity with demographic and environmental data? Data integration shows strong potential to deepen our understanding of migratory connectivity as a dynamic ecological process, especially if the gaps can be bridged between connectivity, population and environmental models

A synthesis of recent tools and perspectives in migratory connectivity studies

International audienceMigration movements connect breeding and non-breeding bird populations over the year. Such links, referred to as migratory connectivity, have important implications for migratory population dynamics as they dictate the consequences of localised events for the whole population network. This calls for concerted efforts to understand migration processes for large-scale conservation. Over the last 20 years, the toolbox to investigate connectivity patterns has expanded and studies now consider migratory connectivity over a broader range of species and contexts. Here, we summarise recent developments in analysing migratory connectivity, focusing on strategies and challenges to pooling various types of data to both optimise and broaden the scope of connectivity studies. We find that the different approaches used to investigate migratory connectivity still have complementary strengths and weaknesses, whether in terms of cost, spatial and temporal resolution, or challenges in obtaining large sample sizes or connectivity estimates. Certain recent developments offer particularly promising prospects: robust quantitative models for banding data, improved precision of geolocators and accessibility of telemetry tracking systems, and increasingly precise probabilistic assignments based on genomic markers or large-scale isoscapes. In parallel, studies have proposed various ways to combine the information of different datasets, from simply comparing the connectivity patterns they draw to formally integrating their analyses. Such data combinations have proven to be more accurate in estimating connectivity patterns, particularly for integrated approaches that offer promising flexibility. Given the diversity of available tools, future studies would benefit from a rigorous comparative evaluation of the different methodologies to guide data collection to complete migration atlases: where and when should data be collected during the migratory cycle to best describe connectivity patterns? Which data are most favourable to combine, and under what conditions? Are there methods for combining data that are better than others? Can combination methods be improved by adjusting the contribution of the various data in the models? How can we fully integrate connectivity with demographic and environmental data? Data integration shows strong potential to deepen our understanding of migratory connectivity as a dynamic ecological process, especially if the gaps can be bridged between connectivity, population and environmental models

Familiarity drives social philopatry in an obligate colonial breeder with weak interannual breeding-site fidelity

Repeated association between subsets of individuals is a common feature of species living in social groups. Because colonial breeding, an extreme case of group living, is associated with certain group behaviour, colonial species are interesting study models to explore the occurrence of social bonds between individuals. As colonial species are usually highly philopatric, disentangling the fidelity to a breeding site from the fidelity to a group of individuals is challenging. Slender-billed gull, Chroicocephalus genei, colonies, however, relocate almost yearly. This behaviour makes it possible to study individual associations over several years, i.e. associations between individuals breeding in the same colony in more than 1 year. To quantify and identify the mechanisms that favour repeated individual associations across years, we analysed data from 14 years of observations of 953 individually marked gulls. Our results showed that some individuals repeatedly bred together across breeding seasons despite the colony moving every year. The probability of an individual selecting a colony increased with an increase in the number of birds that had bred in the same colony as that individual the previous year and not the overall number at the colony. However, we found yearly variation in group tenacity levels and that colony breeding failure favoured splitting of the groups. We also found that association rates rapidly decreased across years but stayed higher than random associations during 2 consecutive years after the first observations. Moreover, over the entire study period, we plotted a bipartite network and found that all colonies and individuals in the population were fully connected. This study reveals group tenacity across years in a colonial bird. Evolutionary pressures as well as the mechanisms favouring social bond persistence across years in colonial birds, however, need further research

Familiarity drives social philopatry in an obligate colonial breeder with weak interannual breeding-site fidelity

Repeated association between subsets of individuals is a common feature of species living in social groups. Because colonial breeding, an extreme case of group living, is associated with certain group behaviour, colonial species are interesting study models to explore the occurrence of social bonds between individuals. As colonial species are usually highly philopatric, disentangling the fidelity to a breeding site from the fidelity to a group of individuals is challenging. Slender-billed gull, Chroicocephalus genei, colonies, however, relocate almost yearly. This behaviour makes it possible to study individual associations over several years, i.e. associations between individuals breeding in the same colony in more than 1 year. To quantify and identify the mechanisms that favour repeated individual associations across years, we analysed data from 14 years of observations of 953 individually marked gulls. Our results showed that some individuals repeatedly bred together across breeding seasons despite the colony moving every year. The probability of an individual selecting a colony increased with an increase in the number of birds that had bred in the same colony as that individual the previous year and not the overall number at the colony. However, we found yearly variation in group tenacity levels and that colony breeding failure favoured splitting of the groups. We also found that association rates rapidly decreased across years but stayed higher than random associations during 2 consecutive years after the first observations. Moreover, over the entire study period, we plotted a bipartite network and found that all colonies and individuals in the population were fully connected. This study reveals group tenacity across years in a colonial bird. Evolutionary pressures as well as the mechanisms favouring social bond persistence across years in colonial birds, however, need further research

Insights on dispersal and recruitment paradigms: sex- and age-dependent variations in a nomadic breeder

Correction DOI: 10.1007/s00442-017-4001-6 (WOS:000419477800010)International audienceSex- and age-dependence in recruitment and dispersal are often explained by costs arising from competition for holding a breeding territory over the years-a typical feature of species living in stable habitats. For instance, long-lived birds with male territoriality often exhibit large variation in recruitment age and higher dispersal in females and young individuals. As a corollary, we expected that species with ephemeral habitat suitability, and hence nomadic breeding, would show weak age- and sex-dependence in dispersal and low variation in recruitment age, because territory ownership is not maintained over the years. In addition, the higher cost of reproduction in females might not be (over)compensated for by costs of territoriality in males. Accordingly, females would recruit later than males. We explored these variations using multievent capture-recapture models over 13 years, 3479 (2392 sexed) slender-billed gulls (Chroicocephalus genei) and 45 colony sites along the French Mediterranean coast. As expected, variability in recruitment age was low with males recruiting earlier than females. Nonetheless, dispersal in and out of the study area decreased with age and was slightly higher in males than in females. Decreased dispersal with age might result from foraging benefits associated with increased spatial familiarity. Higher dispersal in males might be explained by a male-biased sex ratio or higher philopatry benefits in females (arising from their higher cost of reproduction). Sex- and age-dependent dispersal and recruitment may thus occur in the absence of year-to-year breeding territory ownership, which stresses the importance of considering other processes in shaping recruitment and dispersal patterns

Is hunting nonintentionally selective? A test using game bird capture-dead recoveries

Selective hunting has various impacts that need to be considered for the conservation and management of harvested populations. The consequences of selective harvest have mostly been studied in trophy hunting and fishing, where selection of specific phenotypes is intentional. Recent studies, however, show that selection can also occur unintentionally. With at least 52 million birds harvested each year in Europe, it is particularly relevant to evaluate the selectivity of hunting on this taxon. Here, we considered 211,806 individuals belonging to 7 hunted bird species to study unintentional selectivity in harvest. Using linear mixed models, we compared morphological traits (mass, wing, and tarsus size) and body condition at the time of banding between birds that were subsequently recovered from hunting during the same year as their banding, and birds that were not recovered. We did not find any patterns showing systematic differences between recovery categories, among our model species, for the traits we studied. Moreover, when a difference existed between recovery categories, it was so small that its biological relevance can be challenged. Hunting of birds in Europe therefore does not show any form of strong selectivity on the morphological and physiological traits that we studied and should hence not lead to any change of these traits either by plastic or by evolutionary response

Is hunting nonintentionally selective? A test using game bird capture‐dead recoveries

International audienceSelective hunting has various impacts that need to be considered for the conservationand management of harvested populations. The consequences of selective harvesthave mostly been studied in trophy hunting and fishing, where selection of specificphenotypes is intentional. Recent studies, however, show that selection can alsooccur unintentionally. With at least 52 million birds harvested each year in Europe, itis particularly relevant to evaluate the selectivity of hunting on this taxon. Here, weconsidered 211,806 individuals belonging to 7 hunted bird species to study uninten-tional selectivity in harvest. Using linear mixed models, we compared morphologicaltraits (mass, wing, and tarsus size) and body condition at the time of banding betweenbirds that were subsequently recovered from hunting during the same year as theirbanding, and birds that were not recovered. We did not find any patterns showingsystematic differences between recovery categories, among our model species, forthe traits we studied. Moreover, when a difference existed between recovery catego-ries, it was so small that its biological relevance can be challenged. Hunting of birds inEurope therefore does not show any form of strong selectivity on the morphologicaland physiological traits that we studied and should hence not lead to any change ofthese traits either by plastic or by evolutionary response

Multi-sensor data loggers identify the location and timing in four poaching cases of the endangered Eurasian Curlew Numenius arquata

International audienc

Building spaces of interactions between researchers and managers: Case studies with wildlife monitoring and conservation in France

International audience1. To document and halt biodiversity loss, monitoring, quantifying trends and assessing management and conservation strategies on wildlife populations and communities are crucial steps. 2. With increasing technological innovations, more and more data are collected and new quantitative methods are constantly developed. These rapid developments come with an increasing need for analytical skills, which are hardly accessible to managers. On the other hand, researchers spend more and more time on research grant applications and administrative tasks, which leaves fewer opportunities for knowledge transfer. This situation tends to increase the gap between researchers and managers. Here, we illustrate how to fill this gap by presenting two long-term collaborations between a research unit—Centre for Functional and Evolutionary Ecology; CEFE—and a national agency—French Biodiversity Agency; OFB. 3. The first example is a collaboration providing statistical support to national parks for the design and implementation of scientific monitoring protocols. It relies on the recruitment of a research engineer funded by OFB and physically based at CEFE, who works closely with OFB and managers. The second example is a collaboration on the management of large carnivores. For more than 10 years, it has involved several PhD students and post-doctoral fellows co-supervised by CEFE and OFB, and has recently resulted in the recruitment of a permanent OFB researcher who works half-time at CEFE and half-time at OFB. These case studies illustrate the modalities of collaborative work between public institutions acting at different levels of biodiversity conservation for the co-construction of research agendas and the exchange of knowledge. 4. These collaborations also bring out some challenges. Inter-knowledge and mutual learning remain difficult at scales larger than that of the teams concerned. The staff working at this interface needs to possess good listening skills, respect all partners' needs and demonstrate flexibility. Knowledge exchanges require time, thus reducing productivity according to quantitative metrics such as scientific publications or institutional reports. These collaborations can therefore be difficult to assume socially, and remain tenuous because they rely on a good understanding of the differences in governance of the various partners. 5. Based on our experience, success is favoured by long-term and close relationships, and by co-construction of projects at early stage. Sharing a space (i.e. office or building) facilitates face-to- face interactions during planned work sessions and casual meetings that build up a shared scientific culture and mutual trust