PUBLICACIÓN CIENTÍFICA

Weak large‐scale population genetic structure in a philopatric seabird, the European Shag Phalacrocorax aristotelis

Enlace mardeaves Phalacrocorax aristotelis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,
Barlow, E.J., Daunt, F., Wanless, S., Alvarez, D., Reid, J.M. and Cavers, S., 2011. Weak large‐scale population genetic structure in a philopatric seabird, the European Shag Phalacrocorax aristotelis. Ibis, 153(4), pp.768-778.
Quantifying population genetic structure is fundamental to testing hypotheses regarding gene flow, population divergence and dynamics across large spatial scales. In species with highly mobile life-history stages, where it is unclear whether such movements translate into effective dispersal among discrete philopatric breeding populations, this approach can be particularly effective. We used seven nuclear microsatellite loci and mitochondrial DNA (ND2) markers to quantify population genetic structure and variation across 20 populations (447 individuals) of one such species, the European Shag, spanning a large geographical range. Despite high breeding philopatry, rare cross-sea movements and recognized subspecies, population genetic structure was weak across both microsatellites and mitochondrial markers. Furthermore, although isolation-by-distance was detected, microsatellite variation provided no evidence that open sea formed a complete barrier to effective dispersal. These data suggest that occasional long-distance, cross-sea movements translate into gene flow across a large spatial scale. Historical factors may also have shaped contemporary genetic structure: cluster analyses of microsatellite data identified three groups, comprising colonies at southern, mid- and northern latitudes, and similar structure was observed at mitochondrial loci. Only one private mitochondrial haplotype was found among subspecies, suggesting that this current taxonomic subdivision may not be mirrored by genetic isolation.

Multilocus population analysis of Gavia immer (Aves: Gaviidae) mtDNA reveals low genetic diversity and lack of differentiation across the species breeding range

Enlace mardeaves Gavia immer,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,

Bartolomé, C., Maside, X., Camphuysen, K.C., Heubeck, M. & Bao, R., 2011. Multilocus population analysis of Gavia immer (Aves: Gaviidae) mtDNA reveals low genetic diversity and lack of differentiation across the species breeding range. Organisms Diversity & Evolution, 11(4), pp.307-316.

We analyzed the patterns of nucleotide sequence variation at three mitochondrial DNA loci, the noncoding mitochondrial control region and two genes (cytochrome b and cytochrome oxidase I) of Gavia immer in the largest collection of wintering individuals from Southern Europe to date. The sample consisted of 33 birds, oiled during the 2002/2003 Prestige tanker spill and washed ashore on the Galician coast (NW Iberian Peninsula). The aims of the study were to investigate the levels of standing genetic variation in the species, and to identify the geographic origin of these wintering birds. To do this, all available sequences of these loci, mostly from North American specimens collected from both the Atlantic and Pacific coasts, were retrieved from GenBank and included in the analysis. Overall, only 14 genetic variants were detected in the nearly 2 Kb surveyed, which reflects very low levels of nucleotide site diversity in this species. Interestingly, all variants were found at very low frequencies, and there was no indication of any clear subdivision in the G. immer population. This genetic profile is consistent with G. immer being a single panmictic population of small effective population size as compared with other seabirds. These circumstances preclude identification of the breeding regions of these wintering birds relying solely on genetic data. In the light of these results, possible causes, and the genetic and ecological consequences, of this demographic scenario are discussed.

The yellow-legged gull, Larus michahellis, an occasional predator of Timon lepidus in the Atlantic Islands National Park (Galicia, NW Spain)

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,

Piorno, V., Fernández-Bouzas, J.A. & Velo-Antón, G. The yellow-legged gull, Larus michahellis, an occasional predator of Timon lepidus in the Atlantic Islands National Park (Galicia, NW Spain). Bol. Asoc. Herpetol. Esp. 27(1). (2016).

El lagarto ocelado (Timon lepidus) mantiene poblaciones de gran interés en varias islas, tanto por su estatus de conservación como por las particulares interacciones ecológicas que en ellas se desarrollan. En el caso del Parque Nacional de las Islas Atlánticas de Galicia, esta especie convive con una importante colonia de cría de gaviota patiamarilla (Larus michahellis). Desde el año 2009 hasta 2015 hemos detectado en este Parque Nacional siete casos de consumo de T. lepidus por L. michahellis. Se trata de una conducta nunca antes documentada y de reciente aparición, que podría estar relacionada con los efectos que el cierre de vertederos y la reducción de los descartes pesqueros están teniendo en esta especie de gaviota. El carácter ocasional de esta depredación no hace esperar efectos apreciables en estas poblaciones insulares de lagarto ocelado.

Las colonias de aves marinas de la costa Occidental de Galicia. Características, censo y evolución de sus poblaciones

Enlace mardeaves Larus fuscus,Larus michahellis,Phalacrocorax aristotelis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO,Rissa tridactyla,Uria aalge ,,,

Bárcena, F. & Souza, J.A. Las colonias de aves marinas de la costa Occidental de Galicia. Características, censo y evolución de sus poblaciones. Ecología 1. (1987). ISSN 0214-0896

 

Sex-specific growth in the European shag Stictocarbo aristotelis, a sexually dimorphic seabird

Enlace mardeaves Phalacrocorax aristotelis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,

Velando, A., Graves, J. & Freire, J. Sex-specific growth in the European shag Stictocarbo aristotelis, a sexually dimorphic seabird. Ardea 88, 2 (2000).

The European Shag Stictocarbo aristotelis is dimorphic in body size: males are 22% heavier than females . We used molecular techniques to sex of 25 male and 18 female chicks in colonies from the Cíes Islands (NW Spain). Discriminant functions were then obtained based on morphometric variables (culmen, head, wing and tarsus length) measured throughout the growth of
the sexed birds . Once chicks were 25 days of age the discriminant functions accurately classified over 95% of cases, and at 30 days of 100% of cases. Using these functions we retrospectively sexed another 30 males and 35 females to examine the growth of the two sexes. The growth of the different variables was fitted to a logistic model. Culmen growth was found to be similar in both sexes. The asymptotic head size was larger in males but had the same growth constant as in females. The wing, tarsus and body mass asymptotes were larger in males, but females had a higher growth rate. The first principal component (PC I), extracted from a principal component analysis of the morphometric variables, may be considered as a synoptic descriptor of body size. The differentiation in mass growth between males and females started when the birds were 15 days old. However, body size (PC1) was not distinguished until they were 30 days old. During the first growth stage females were similar in body size to males due to their faster growth rate. This would suggest that the smaller sex (the females) has the same competitive ability as the larger sex and that the hierarchy in the early stages of growth would be contingent upon hatching order and not sex .

Postfledging crèche behavior in the European shag

Enlace mardeaves Phalacrocorax aristotelis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,

Velando, A. Postfledging crèche behavior in the European shag. Journal of Ethology 19, 121–127 (2001).

Formation of a postfledgling crèche in the European shag Phalacrocorax aristotelis on the Cíes Islands (northwest Spain) was studied. There was no relationship between the number of birds in a crèche and environmental temperature. Moreover, the number of juveniles in the crèche was not correlated with adult peck rate per juvenile. Also, predation was not reported on the studied population. Therefore, their postfledging crèche did not serve as protection from thermal stress, aggressiveness of adults, or predators. In the crèche studied, fledglings are faithful to their perch, which serves as a functional unit where they form a group consisting of stable members. I postulate that there may be advantages in the formation of crèches, which allow adults to be able to locate their young and continue their postfledging parental care and also enable chicks to exercise and develop fishing skills. Adults remained in the crèche during the entire period, but their number depended on the hour and tide, which would be associated with the effectiveness of fishing according to these factors. Moreover, crèches may facilitate finding mates and forming feeding groups.

Conservación del Cormorán moñudo en el Parque Nacional de las Islas Atlánticas de Galicia

Enlace mardeaves Phalacrocorax aristotelis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,

Velando, A. & Munilla, I. Conservación del Cormorán moñudo en el Parque Nacional de las Islas Atlánticas de Galicia. Boletín GIAM 35 9 (2012).

Recientemente hemos realizado, el plan de conservación del cormorán moñudo, Phalacrocorax aristotelis, en el Parque Nacional marítimo y terrestre de las Islas Atlánticas de Galicia. Se ha estudiado el uso que hacen los moñudos del espacio marítimo, lo que ha permitido establecer que variables físicas, como la profundidad y la presencia de fondos de arena, son relevantes para explicar su distribución en el medio marino. El análisis de recuperaciones y de los avistamientos de aves marcadas durante el estudio, indican que los cormoranes del Parque Nacional constituyen una unidad de conservación válida. Los censos señalan un fuerte y generalizado descenso de la población nidificante, pues se ha pasado de 2047 parejas en 2004 a 911 en 2009 (-56%). El estudio identificó asimismo los posibles factores responsables de la mala situación que atraviesa el cormorán moñudo en el Parque Nacional: a) Aumento de la mortalidad en artes menores de enmalle (betas, miños y trasmallos); b) Reducción en la provisión de lanzones (Ammodytidae), probablemente achacable a los efectos prolongados de la marea negra del “Prestige”; c) La interferencia de las embarcaciones de recreo, que excluyen a los cormoranes de sus mejores zonas de alimentación; y, d) La reciente aparición de ejemplares de visón americano en las colonias de cría. Al tener en cuenta el efecto de los factores limitantes identificados sobre las variables demográficas, se puso de manifiesto que tan solo mediante la adopción de varias medias de manejo que combinen la reducción de la mortalidad de adultos y juveniles con un reforzamiento del éxito reproductivo, es posible invertir la tendencia que, desde hace más de 15 años viene arrastrando la población de cormoranes del Parque Nacional. Según los resultados de los modelos de simulación, los esfuerzos de conservación han de concentrarse en las medidas que incidan en el aumento de la supervivencia de los adultos, pues son las que más atenúan el declive poblacional; por lo tanto, las medidas encaminadas a reducir la mortalidad en artes de pesca y la depredación de los carnívoros terrestres deben ser priorizadas.

Disturbance to a foraging seabird by sea-based tourism: Implications for reserve management in marine protected areas

Enlace mardeaves Phalacrocorax aristotelis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,,

Velando, A. & Munilla, I. Disturbance to a foraging seabird by sea-based tourism: Implications for reserve management in marine protected areas. Biological Conservation 144, 1167–1174 (2011).

The provision of recreational opportunities is one of the important human goals of marine protected areas. However, as levels of recreational use increase, human disturbance is likely to cause significant detrimental effects upon wildlife. Here we evaluate the best managing options to mitigate the impact of sea-based tourism on the foraging activity of an endangered population of European shags, Phalacrocorax aristotelis, in a coastal marine protected area (Cíes islands, north-western Iberia). Boat disturbance elicited a characteristic avoidance behavior that resulted in a substantial reduction in foraging activity as levels of boat use increased. Moreover, boats excluded shags from the best feeding areas, resulting in higher densities of foragers in areas of little boat traffic. We used a behavioral model to explore the effects of managing strategies aimed at reducing the impact of boats on the foraging activity of shags. Our model suggested that in low boat disturbance scenarios limiting the number of boats using the reserve would be a better management option than habitat protection (i.e. the establishment of set-aside areas free of boat traffic). On the contrary, when boat disturbance levels are high the protection of habitat is recommendable, even if spatial variation in habitat quality is unknown or poorly assessed. Our study stresses the point that management strategies to minimize disturbance to foraging seabirds may depend on the spatial overlap between sea-based recreational activities and foraging seabirds and the spatial variation in marine habitat quality for seabirds.

EROD activity and stable isotopes in seabirds to disentangle marine food web contamination after the Prestige oil spill

Enlace mardeaves Phalacrocorax aristotelis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,

Velando, A., Munilla, I., López-Alonso, M., Freire, J. & Pérez, C. EROD activity and stable isotopes in seabirds to disentangle marine food web contamination after the Prestige oil spill. Environmental Pollution 158, 1275–1280 (2010).

In this study, we measured via surgical sampling hepatic EROD activity in yellow-legged gulls from oiled and unoiled colonies, 17 months after the Prestige oil spill. We also analyzed stable isotope composition in feathers of the biopsied gulls, in an attempt to monitor oil incorporation into marine food web. We found that yellow-legged gulls in oiled colonies were being exposed to remnant oil as shown by hepatic EROD activity levels. EROD activity was related to feeding habits of individual gulls with apparent consequences on delayed lethality. Capture–recapture analysis of biopsied gulls suggests that the surgery technique did not affect gull survival, giving support to this technique as a monitoring tool for oil exposure assessment. Our study highlights the combination of different veterinary, toxicological and ecological methodologies as a useful approach for the monitoring of exposure to remnant oil after a large oil spill.