Response of breeding European Storm Petrels to habitat change

International audienceMainly through trampling and manuring, ground-nesting seabirds induced significant habitat changes both on vegetation cover and soil in one of the largest French colonies of European Storm Petrel , Habitat deterioration led to a high level of erosion and the collapse of many former Rabbit burrows previously occupied by breeding Storm Petrels. The loss of burrows accelerated in recent years since Great Cormorants bred on the islet with growing numbers. The main consequence of this disturbance was at first shifting of breeding Storm Petrels from burrows to rocky sites, reflecting some behavioral plasticity to buffer environmental variability. But over 18 years, a significant decrease in breeding numbers of Storm Petrels was recorded and attributed to continuous nest site destruction. Thus, other behavioral responses were also suspected, such as temporary non-breeding or emigration of birds that have to find a new nest site. Such a problem of heavy erosion and loss of nesting habitat could induce serious detrimental effects on burrowing seabirds breeding in a limited number of colonies

Population trends of Lesser Black-backed, Herring and Great Black-backed Gulls Larus fuscus, L. argentatus, L. marinus in the Molène archipelago (Brittany, France): a check-up after 50 years of colony monitoring

A fifty-year survey of breeding populations of Lesser Black-backed, Herring and Great Black-backed Gulls Larus fuscus, L. argentatus, L. marinus in the Molène archipelago (Brittany, France) points out radical changes and divergent demographic trends between these species. Gulls were absent from the study area in the beginning of the 20th century, the first proof of breeding being recorded in the early 1950s. From the 1960s to the 1980s, numbers increased rapidly but their multiplication rates progressively slowed. The Herring Gull initially was the more abundant species, with about 5 800 pairs in 1988, but a severe decline occurred leading to only 975 pairs in 2004 (– 83% in 16 years). For the Lesser Black-backed Gull, the highest level was recorded in 1992 with about 8 580 pairs but a decline also occurred and 4 735 pairs bred in 2004 (– 45% in 12 years). Only the Great Black-backed Gull showed a positive trend over the whole study period but stabilization seems to have occurred recently and the 466 breeding pairs in 2004 constituted the highest number recorded. The demographic changes observed at the scale of the study area are a good illustration of the changes recorded at the regional and national scale for the three species. The main factors responsible for these evolutions seem to be variability in the accessibility and abundance of anthropogenic food resources (refuse dumps and fisheries) as well as inter- and intra-specific competition (spatial competition, competition for food and predation). The actual state of knowledge does not allow to prioritize these different factors or to apprehend their interactions. The present results underline the necessity to develop ecological studies on these three gull species in the Molène archipelago. Moreover, at a fundamental level, mixed colonies of gulls constitute an interesting model to study predation and both intra- and inter-specific competition acting on community dynamics in an insular environmentL'analyse de l'évolution numérique des populations de Goélands bruns, argentés et marins Larus fuscus, argentatus, marinus durant une cinquantaine d'années dans l'archipel de Molène en Bretagne met en évidence de profonds changements et des divergences de tendance démographique selon les espèces. Au début du XXe siècle, ces espèces n'étaient pas présentes et les premières preuves de reproduction sont apportées au début des années 1950. Des années 1960 aux années 1980, les effectifs augmentent rapidement mais les rythmes d'accroissement se sont progressivement ralentis. Si le Goéland argenté a été le plus abondant, avec environ 5 800 couples en 1988, un déclin majeur survient par la suite et il ne reste que 975 couples en 2004 (- 83 %). Pour le Goéland brun, le niveau maximum est atteint en 1992 avec environ 8 580 couples, mais un déclin se produit également et 4 735 couples nichent en 2004 (-45 %). Seul le Goéland marin affiche une tendance positive sur l'ensemble de la période d'étude, mais une stabilisation des effectifs semble se produire et les 466 couples dénombrés en 2004 représentent le niveau maximum actuellement connu. Ces évolutions enregistrées à l'échelle locale illustrent de façon plus marquée celles qui s'observent également à l'échelle nationale pour ces trois espèces de goélands. Les facteurs déterminants responsables de ces évolutions apparaissent être à la fois des variations de la disponibilité et l'abondance des ressources alimentaires d'origine humaine (décharges et pêcheries) et des phénomènes de compétition interspécifique et intraspécifique (compétition spatiale, compétition pour la nourriture et prédation). L'état actuel des connaissances ne permet pas de hiérarchiser ces différents facteurs ni d'appréhender leurs interactions. Le présent bilan souligne donc la nécessité de développer des études sur l'écologie de ces trois espèces dans l'archipel de Molène. Par ailleurs, au plan fondamental, les colonies plurispécifiques de goélands constituent un intéressant modèle d'étude de la prédation et de la compétition intra- et interspécifique agissant sur la dynamique des communautés en milieu insulaire

Molecular evidence for gender differences in the migratory behaviour of a small seabird

Molecular sexing revealed an unexpectedly strong female bias in the sex ratio of pre-breeding European Storm Petrels (Hydrobates pelagicus), attracted to playback of conspecific calls during their northwards migration past SW Europe. This bias was consistent across seven years, ranging from 80.8% to 89.7% female (mean annual sex ratio ± SD = 85.5% female ±4.1%). The sex ratio did not differ significantly from unity (i.e., 50% female) among (i) Storm Petrel chicks at a breeding colony in NW France, (ii) adults found dead on beaches in Southern Portugal, (iii) breeding birds attending nest burrows in the UK, captured by hand, and (iv) adults captured near a breeding colony in the UK using copies of the same sound recordings as used in Southern Europe, indicating that females are not inherently more strongly attracted to playback calls than males. A morphological discriminant function analysis failed to provide a good separation of the sexes, showing the importance of molecular sexing for this species. We found no sex difference in the seasonal or nocturnal timing of migration past Southern Europe, but there was a significant tendency for birds to be caught in sex-specific aggregations. The preponderance of females captured in Southern Europe suggests that the sexes may differ in migration route or in their colony-prospecting behaviour during migration, at sites far away from their natal colonies. Such differences in migration behaviour between males and females are poorly understood but have implications for the vulnerability of seabirds to pollution and environmental change at sea during the non-breeding season

L’apport du GPS à la connaissance de l’espace de vie des oiseaux marins

L’oiseau marin constitue un indicateur de l’état de conservation du milieu naturel et notamment de l'environnement marin. Il occupe le littoral uniquement au cours de la saison de nidification, l’exploitant dans le temps et dans l’espace de manière originale. Afin de mieux saisir ces spécificités, des GPS ont été utilisés pour suivre les déplacements des Guillemots de Troïl nichant au cap Fréhel (Bretagne). Cette démarche constitue un apport méthodologique à l’analyse de l’espace et met en évidence les traces des oiseaux et leurs différents comportements en mer (nettoyage, nourrissage, repos). Chaque trajet est caractérisé par sa durée, sa distance, son éloignement à la colonie et la période durant laquelle il s’est déplacé. Ensemble, ces trajets définissent un espace de vie, délimité par une aire maximale dans laquelle l’oiseau marin évolue, mais aussi caractérisée par zones plus ou moins fréquentées, dans lesquelles la bathymétrie, les courants marins, la présence de bancs de poissons jouent un rôle fondamental. Cet espace ainsi précisé conduit enfin à ré-interroger les autres usages en mer et les actuelles mesures de protection de l’environnement marin.Seabirds are an indicator of the state of nature conservation, particularly the marine environment. They occupy the coastline only during nesting season, exploiting it in time and space in an original way both time-wise and space-wise. In order to better understand these particularities, GPS devices were used to track the movements of Common Murre nesting at Cap Fréhel (Brittany). This approach is a methodological contribution to the analysis of space and highlights the tracks of birds and their different behaviors at sea (cleaning, feeding, resting). Each trip is characterized by its duration, its distance, its remoteness from the colony and the period during which it happened. Together, these trips define a living space, delimited by a maximum area in which the seabirds evolves, but also characterized by more or less frequented areas, in which the bathymetry, the marine currents, the presence of fish play an important role. This space thus clarified allows us to put into perspective the other uses of sea and the current protection measures of the marine environment

Co‐developing guidance for conservation: An example for seabirds in the North‐East Atlantic in the face of climate change impacts

Conservation guidance—an authoritative source of information and recommendations explicitly supporting decision-making and action regarding nature conservation—represents an important tool to communicate evidence-based advice to conservation actors. Given the rapidly increasing pressure that climate change poses to biodiversity, producing accessible, well-informed guidance on how to best manage the impacts and risks of changing climatic conditions is particularly urgent. Guidance documents should ideally be produced with multistage input from stakeholders who are likely to use and implement such advice; however, this step can be complicated and costly, and remains largely unformalized. Moreover, there is currently little direct evidence synthesized for actions that specifically target climate change and guidance remains largely absent. Here, we introduce a process for co-developing guidance for species conservation in the face of climate change, using seabirds in the North-East Atlantic as a case study. Specifically, we collated evidence on climate change vulnerability and possible conservation actions using literature synthesis, stakeholder surveys, and ecological modeling. This evidence base was then discussed, refined, and expanded using structured stakeholder workshops. We summarize the knowledge gained through stakeholder engagement and provide recommendations for future international efforts to co-produce conservation guidance for managing wildlife, in the context of a rapidly changing climate.info:eu-repo/semantics/publishedVersio

Co-developing guidance for conservation: an example for seabirds in the North-East Atlantic in the face of climate change impacts

Conservation guidance—an authoritative source of information and recommendations explicitly supporting decision-making and action regarding nature conservation—represents an important tool to communicate evidence-based advice to conservation actors. Given the rapidly increasing pressure that climate change poses to biodiversity, producing accessible, well-informed guidance on how to best manage the impacts and risks of changing climatic conditions is particularly urgent. Guidance documents should ideally be produced with multistage input from stakeholders who are likely to use and implement such advice; however, this step can be complicated and costly, and remains largely unformalized. Moreover, there is currently little direct evidence synthesized for actions that specifically target climate change and guidance remains largely absent. Here, we introduce a process for co-developing guidance for species conservation in the face of climate change, using seabirds in the North-East Atlantic as a case study. Specifically, we collated evidence on climate change vulnerability and possible conservation actions using literature synthesis, stakeholder surveys, and ecological modeling. This evidence base was then discussed, refined, and expanded using structured stakeholder workshops. We summarize the knowledge gained through stakeholder engagement and provide recommendations for future international efforts to co-produce conservation guidance for managing wildlife, in the context of a rapidly changing climate

Evolution des populations de Goélands bruns, argentés et marins Larus fuscus, Larus argentatus et Larus marinus dans l’archipel de Molène (Bretagne, France) : bilan de 50 ans de suivi des colonies

Population trends of Lesser Black-backed, Herring and Great Black-backed Gulls Larus fuscus, L. argentatus, L. marinus in the Molène archipelago (Brittany, France) : a check-up after 50 years of colony monitoring. — A fifty-year survey of breeding populations of Lesser Black-backed, Herring and Great Black-backed Gulls Larus fuscus, L. argentatus, L. marinus in the Molène archipelago (Brittany, France) points out radical changes and divergent demographic trends between these species. Gulls were absent from the study area in the beginning of the 20th century, the first proof of breeding being recorded in the early 1950s. From the 1960s to the 1980s, numbers increased rapidly but their multiplication rates progressively slowed. The Herring Gull initially was the more abundant species, with about 5 800 pairs in 1988, but a severe decline occurred leading to only 975 pairs in 2004 (– 83% in 16 years). For the Lesser Black-backed Gull, the highest level was recorded in 1992 with about 8 580 pairs but a decline also occurred and 4 735 pairs bred in 2004 (– 45% in 12 years). Only the Great Black-backed Gull showed a positive trend over the whole study period but stabilization seems to have occurred recently and the 466 breeding pairs in 2004 constituted the highest number recorded. The demographic changes observed at the scale of the study area are a good illustration of the changes recorded at the regional and national scale for the three species. The main factors responsible for these evolutions seem to be variability in the accessibility and abundance of anthropogenic food resources (refuse dumps and fisheries) as well as inter-and intra-specific competition (spatial competition, competition for food and predation). The actual state of knowledge does not allow to prioritize these different factors or to apprehend their interactions. The present results underline the necessity to develop ecological studies on these three gull species in the Molène archipelago. Moreover, at a fundamental level, mixed colonies of gulls constitute an interesting model to study predation and both intra-and inter-specific competition acting on community dynamics in an insular environment.L’analyse de l’évolution numérique des populations de Goélands bruns, argentés et marins Larus fuscus, argentatus, marinus durant une cinquantaine d’années dans l’archipel de Molène en Bretagne met en évidence de profonds changements et des divergences de tendance démographique selon les espèces. Au début du XXe siècle, ces espèces n’étaient pas présentes et les premières preuves de reproduction sont apportées au début des années 1950. Des années 1960 aux années 1980, les effectifs augmentent rapidement mais les rythmes d’accroissement se sont progressivement ralentis. Si le Goéland argenté a été le plus abondant, avec environ 5 800 couples en 1988, un déclin majeur survient par la suite et il ne reste que 975 couples en 2004 (– 83 %). Pour le Goéland brun, le niveau maximum est atteint en 1992 avec environ 8 580 couples, mais un déclin se produit également et 4 735 couples nichent en 2004 (– 45 %). Seul le Goéland marin affiche une tendance positive sur l’ensemble de la période d’étude, mais une stabilisation des effectifs semble se produire et les 466 couples dénombrés en 2004 représentent le niveau maximum actuellement connu. Ces évolutions enregistrées à l’échelle locale illustrent de façon plus marquée celles qui s’observent également à l’échelle nationale pour ces trois espèces de goélands. Les facteurs déterminants responsables de ces évolutions apparaissent être à la fois des variations de la disponibilité et l’abondance des ressources alimentaires d’origine humaine (décharges et pêcheries) et des phénomènes de compétition interspécifique et intraspécifique (compétition spatiale, compétition pour la nourriture et prédation). L’état actuel des connaissances ne permet pas de hiérarchiser ces différents facteurs ni d’appréhender leurs interactions. Le présent bilan souligne donc la nécessité de développer des études sur l’écologie de ces trois espèces dans l’archipel de Molène. Par ailleurs, au plan fondamental, les colonies plurispécifiques de goélands constituent un intéressant modèle d’étude de la prédation et de la compétition intra-et interspécifique agissant sur la dynamique des communautés en milieu insulaire.Cadiou Bernard, Yésou Pierre. Evolution des populations de Goélands bruns, argentés et marins Larus fuscus, Larus argentatus et Larus marinus dans l’archipel de Molène (Bretagne, France) : bilan de 50 ans de suivi des colonies. In: Revue d'Écologie (La Terre et La Vie), tome 61, n°2, 2006. pp. 159-173

Régulation par le recrutemet, la fidélité et la non-reproduction chez un oiseau colonial, la mouette tridactyle (Rissa tridactyla)

A long term study of the Kittiwake colonies of Cap Sizun (Brittany, France) shows that, even though Kittiwakes usually recruit at the age of 4, the population growth rate from year to year is highly correlated with the breeding success of the previous year. This is due to a strong recruitment, a large proportion of breeders, and a high adult fidelity after years of high fecondity. Furthermore, for a given individual breeding performance (breeding success or failure), adult fidelity to the colony and the proportion of breeders in the following year increase with the breeding success of the colony in which they bred in the previous year. This leads us to propose a mechanism of population regulation through Attraction, Recruitment, Non-breeding, and Adult Fidelity, in which breeding success and social context — two characteristics which reflect environmental quality — play prominent roles. These two parameters are the main components of the attraction exerted by a breeding site, i.e. its capacity to recruit new breeders (young or adults) and to retain its own adults as breeders. Breeding success and social context are assessed by potential recruits when prospecting different breeding places. If fecondity and social context are good, prospectors may settle there and recruit in the following year. Prospectors are attracted to nests with chicks, on which they squat when they are momentarily left unattended by the parents after the middle of the rearing period. These squatters are mainly prebreeders or failed breeders ; both are actively looking for a breeding site. Males are more prone to squat on chicks. Prebreeding squatters on chicks show a high proportion of recruitment in the following year : 34 % of prospecting males recruit on one of the nests they have squatted during the previous year, and 24 % on the most consistently squatted nest. Thus, squatting is an appropriation behaviour of a breeding site. The density of parasites influences the colony breeding success : breeding groups with high densities of parasites on the chicks have the lowest fecondity. The appearence of parasites is correlated with a drop in fecondity of the kittiwakes and parasites are likely to be the cause of this reduced fecondity. This acts on the numbers through prospectors’ and adults’ behaviour which in turn can explain the positive correlation between the fecondity in a given year and the rate of population increase in the following year.Cadiou Bernard, Danchin Etienne, Monnat J.Y., Boulinier Thierry. Régulation par le recrutemet, la fidélité et la non-reproduction chez un oiseau colonial, la mouette tridactyle (Rissa tridactyla). In: Revue d'Écologie (La Terre et La Vie), tome 48, n°2, 1993. pp. 163-174