Suchergebnisse

Several studies of marine top predators, above all of seabirds, have analyzed the effects of either individual age or environmental fluctuations on reproduction; nevertheless, little is known about the age patterns in breeding performance in a variable environment. To investigate the simultaneous influence of age and environmental conditions on laying dates and egg volumes, we tested different climate and food availability indices in a transequatorial migratory seabird using female data from a 23-year study. Our results show an improvement in breeding parameters with age (i.e., earlier laying dates and greater egg volumes) but no pattern of senescence in older age groups. The best models showed an interaction of time and age in breeding performance, i.e., the age pattern of breeding performance changed each year likely as a result of environmental variability. Nevertheless, climatic indexes used here explained part of that annual variability: NAO and SOI index accounted for 24 and 20% of deviances in laying dates and egg volume, respectively. Part of that unexplained variability might be related to other processes such as intermittent breeding and the individual quality of breeders, which were not assessed in our study. ; Funds were provided by the Balearic Government (FEDER program) and the Spanish Ministry of Economy and Competitiveness (ref. CGL2013-42203-R). ; Peer reviewed ; Peer Reviewed

Este artículo contiene 18 páginas, 7 figuras, 8 tablas. ; Fisheries have an enormous economic importance, but reconciling their socio-economic features with the conservation and sustainability of marine ecosystems presents major challenges. Bycatch mortality from fisheries is clearly among the most serious global threats for marine ecosystems, affecting a wide range of top predators. Recent estimates report ca. 200,000 seabirds killed annually by bycatch in European waters. However, there is an urgent need to rigorously estimate actual mortality rates and quantify effects of bycatch on populations. The Mediterranean Sea is one of the most impacted regions. Here, we estimate for the first time both bycatch mortality rates and their population-level effects on three endemic and vulnerable Mediterranean taxa: Scopoli's shearwater, Mediterranean shag, and Audouin's gull, that die in different types of fishing gears: longlines, gillnets and sport trolling, respectively. We use multi-event capture–recapture modelling to estimate crucial demographic parameters, including the probabilities of dying in different fishing gears. We then build stochastic demography models to forecast the viability of the populations under different management scenarios. Longline bycatch was particularly severe for adults of Scopoli's shearwaters and Audouin's gulls (ca. 28% and 23% of total mortality, respectively) and also for immature gulls (ca. 90% of mortality). Gillnets had a lower impact, but were still responsible for ca. 9% of juvenile mortality on shags, whereas sport trolling only slightly influenced total mortality in gulls. Bycatch mortality has high population-level impacts in all three species, with shearwaters having the highest extinction risk under current mortality rates. Different life-history traits and compensatory demographic mechanisms between the three species are probably influencing the different bycatch impact: for shearwaters, urgent conservation actions are required to ensure the viability of their populations. Results will be very useful for guiding future seabird conservation policies and moving towards an ecosystem-based approach to sustainable fisheries management. ; Regional Government of the Balearic Islands; European Social Fund; Spanish Ministry of Economy, Grant/Award Number: CGL2013-42203-R; European Union, Grant/Award Number: H2020- 634495 ; Peer reviewed

The control of overabundant vertebrates is often problematic. Much work has focused on population-level responses and overabundance due to anthropogenic subsidies. However, far less work has been directed at investigating responses following the removal of subsidies. We investigate the consequences of two consecutive perturbations, the closure of a landfill and an inadvertent poisoning event, on the trophic ecology (d13C, d15N, and d34S),survival, and population size of an overabundant generalist seabird species, the Yellow-legged Gull (Larus michahellis). We expected that the landfill closure would cause a strong dietary shift and the inadvertent poisoning a decrease in gull population size. As a long-lived species, we also anticipated adult survival to be buffered against the decrease in food availability but not against the inadvertent poisoning event. Stable isotope analysis confirmed the dietary shift towards marine resources after the disappearance of the landfill. Although the survival model was inconclusive, it did suggest that the perturbations had a negative effect on survival, which was followed by a recovery back to average values. Food limitation likely triggered dispersal to other populations, while poisoning may have increased mortality; these two processes were likely responsible for the large fall in population size that occurred after the two consecutive perturbations. Life-history theory suggests that perturbations may encourage species to halt existing breeding investment in order to ensure future survival. However, under strong perturbation pulses the resilience threshold might be surpassed and changes in population density can arise. Consecutive perturbations may effectively manage overabundant species ; A. Payo-Payo was supported by a fellowship from the Spanish Ministry of Education (ref. FPU2012-000869). Funds were also partially provided by the Balearic Government (FEDER Program) and the Spanish Ministry of Economy (ref. CGL2013-42203-R) ; Peer Reviewed

Este artículo contiene 12 páginas, 5 figuras, 5 tablas. ; Recently isolated populations offer a good biological model to infer the evolutionary forces responsible for the current divergences across populations. We coupled genetic, morphometric, ecological, and demographic analyses from three island populations of the endemic Balearic Wall Lizard, Podarcis lilfordi, (Balearic archipelago, Spain) to infer the mechanisms underlying the observed differences in body size. For each population, we described plant community structure, derived a biotic capacity index, and used individual-based data on 1369 lizards captured and released during 6 yr (2009–2015) to estimate population density and body growth patterns. We used genetic data collected on 80 individuals (~27 for each population) to infer genetic divergences across islets and population history. Body size divergences cannot be explained by the ecological or population characteristics. Individual growth was slower in the smallest island, where lizards reached the largest average body size. In addition to having the highest density, results suggested that resource availability does not constrain asymptotic body size, but the speed at which individuals reach it does. The Approximate Bayesian Computation used to infer population history from genetic data supported the occurrence of two bottlenecks in the islet with the highest anthropogenic footprint. We emphasize the need to integrate ecological and genetic data and the importance of considering the effects of past human disturbance as an additional force in being able to model present island fauna. ; GT was supported by I. Hendriks. AR was supported by a JAE fellowship from the Spanish Council of Research. Ethics Committee for Animal Experimentation (CEEA) of Balearic Islands University (Spain) approved the protocol. The authorization to capture and handing animals was given by the Balearic Islands Government (ref: CEP 06/2015). ; Peer reviewed

Marine megafauna, including seabirds, are critically affected by fisheries bycatch. However, bycatch risk may differ on temporal and spatial scales due to the uneven distribution and effort of fleets operating different fishing gear, and to focal species distribution and foraging behaviour. Scopoli's shearwater Calonectris diomedea is a long-lived seabird that experiences high bycatch rates in longline fisheries and strong population-level impacts due to this type of anthropogenic mortality. Analyzing a long-term data set on individual monitoring, we compared adult survival (by means of multi-event capture-recapture models) among three close predator-free Mediterranean colonies of the species. Unexpectedly for a long-lived organism, adult survival varied among colonies. We explored potential causes of this differential survival, by: (1) measuring egg volume as a proxy of food availability and parental condition; (2) building a specific longline bycatch risk map for the species; and (3) assessing the distribution patterns of breeding birds from the three study colonies via GPS tracking. Egg volume was very similar between colonies over time, suggesting that environmental variability related to habitat foraging suitability was not the main cause of differential survival. On the other hand, differences in foraging movements among individuals from the three colonies expose them to differential mortality risk, which likely influenced the observed differences in adult survival. The overlap of information obtained by the generation of specific bycatch risk maps, the quantification of population demographic parameters and the foraging spatial analysis should inform managers about differential sensitivity to the anthropogenic impact at mesoscale level and guide decisions depending on the spatial configuration of local populations. The approach would apply and should be considered in any species where foraging distribution is colony-specific and mortality risk varies spatially. ; Funds were partially provided by the Spanish Ministry of the Economy (ref. CGL2013-42203-R), Consell Insular of Minorca, Universidade da Coruña and Xunta de Galicia (reference GRC2014/050) and the European Union (H2020 RIA- MINOUW Grant, ref. H2020- 634495). GPS-tracking work was supported by two EC-funded LIFE Projectsconducted by SEO/BirdLife: LIFE04NAT/ES/000049 (Marine IBAs in Spain; 2004–2009) and LIFE07NAT/E/000732 (INDEMARES; 2009–2014). ; Peer reviewed

Funding This Project was partially funded by the Govern Balear (Acciones Especiales, AAEE031/2017) and the Spanish Ministry of Innovation and Universities (RESET, ref: CGL2017-85210-P). ASA was funded by the Spanish Ministry of Innovation and Universities Innovation and Universities, the Agencia Estatal de Investigación and the European Social Found (RYC-2017- 22796). Data accessibility Data will be available via the Spanish National Research Council data repository. Sanz-Aguilar, A., Payo-Payo, A., Igual, J. M., Rotger, A., Viñas Torres, M., Picorelli, V., 2019. Storm petrel data sets. https://doi.org/10.20350/digitalCSIC/. Declaration of Competing Interest The authors declare no conflicts of interest. Acknowledgements We thank Esteban Cardona, Oliver Martínez, Raül Luna, Toni Avila, Esther López Marín, Miquel Mas, Enric Real y Santiago de la Vega for their help and support on the colony monitoring. Balearic Islands Government, Sant Josep City Hall, COFIB and Fundación Balearia for their logistic support. Ethical statement This study was authorized by the Reserves des Vedrà es Vedranell i els illots de Ponent, Balearic Government. All aspects of the study were performed according to guidelines established for the ethical treatment of animals and complied with current Spanish regulations. The collection of ticks was authorized by the Balearic Government (Reference: CAP 21/2018). ; Peer reviewed ; Postprint

International audience ; Migratory marine species cross political borders and enter the high seas, where the lack of an effective global management framework for biodiversity leaves them vulnerable to threats. Here, we combine 10,108 tracks from 5775 individual birds at 87 sites with data on breeding population sizes to estimate the relative year-round importance of national jurisdictions and high seas areas for 39 species of albatrosses and large petrels. Populations from every country made extensive use of the high seas, indicating the stake each country has in the management of biodiversity in international waters. We quantified the links among national populations of these threatened seabirds and the regional fisheries management organizations (RFMOs) which regulate fishing in the high seas. This work makes explicit the relative responsibilities that each country and RFMO has for the management of shared biodiversity, providing invaluable information for the conservation and management of migratory species in the marine realm.

International audience ; Migratory marine species cross political borders and enter the high seas, where the lack of an effective global management framework for biodiversity leaves them vulnerable to threats. Here, we combine 10,108 tracks from 5775 individual birds at 87 sites with data on breeding population sizes to estimate the relative year-round importance of national jurisdictions and high seas areas for 39 species of albatrosses and large petrels. Populations from every country made extensive use of the high seas, indicating the stake each country has in the management of biodiversity in international waters. We quantified the links among national populations of these threatened seabirds and the regional fisheries management organizations (RFMOs) which regulate fishing in the high seas. This work makes explicit the relative responsibilities that each country and RFMO has for the management of shared biodiversity, providing invaluable information for the conservation and management of migratory species in the marine realm.

International audience ; Migratory marine species cross political borders and enter the high seas, where the lack of an effective global management framework for biodiversity leaves them vulnerable to threats. Here, we combine 10,108 tracks from 5775 individual birds at 87 sites with data on breeding population sizes to estimate the relative year-round importance of national jurisdictions and high seas areas for 39 species of albatrosses and large petrels. Populations from every country made extensive use of the high seas, indicating the stake each country has in the management of biodiversity in international waters. We quantified the links among national populations of these threatened seabirds and the regional fisheries management organizations (RFMOs) which regulate fishing in the high seas. This work makes explicit the relative responsibilities that each country and RFMO has for the management of shared biodiversity, providing invaluable information for the conservation and management of migratory species in the marine realm.

Migratory marine species cross political borders and enter the high seas, where the lack of an effective global management framework for biodiversity leaves them vulnerable to threats. Here, we combine 10,108 tracks from 5775 individual birds at 87 sites with data on breeding population sizes to estimate the relative year-round importance of national jurisdictions and high seas areas for 39 species of albatrosses and large petrels. Populations from every country made extensive use of the high seas, indicating the stake each country has in the management of biodiversity in international waters. We quantified the links among national populations of these threatened seabirds and the regional fisheries management organizations (RFMOs) which regulate fishing in the high seas. This work makes explicit the relative responsibilities that each country and RFMO has for the management of shared biodiversity, providing invaluable information for the conservation and management of migratory species in the marine realm.