Larus michahellis

Availability of nonpigmentary antioxidant affects red coloration in gulls

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Pérez, C., Lores, M. & Velando, A. Availability of nonpigmentary antioxidant affects red coloration in gulls. Behavioral Ecology 19, 967–973 (2008).

Red, orange, and yellow carotenoid-based colorations displayed by fishes and birds may function as honest sexual signals of the bearer’s quality. However, the mechanisms underlying the expression of these traits and the information they convey are still controversial. Because carotenoids are antioxidants and carotenoid-based pigmentation is bleached as a consequence of oxidative processes, it has been suggested that the pigmentation may signal antioxidant status. We tested this hypothesis in the yellow-legged gull (Larus michahellis), a seabird that exhibits a carotenoid-based red spot on the lower mandible. The availability of a nonpigmentary antioxidant (i.e., vitamin E) to the gulls was modified before egg laying by means of a supplementary feeding experiment. During the incubation period, breeding pairs were captured to assess the intensity of the color and the size of the red bill spots. We measured the plasma level of lipid peroxidation, total antioxidant capacity, and carotenoids. We found that males that received vitamin E supplements had larger red spot than control birds but that color intensity was not affected by the supplements. Moreover, we found that only those plasma carotenoids involved in the red coloration were affected by the antioxidant supplementation, suggesting an active mechanism to increase red coloration. Overall, our results provide experimental evidence for the hypothesis that carotenoid-based coloration reflects the bearer’s antioxidant status in male gulls.

Sublethal effects on seabirds after the Prestige oil-spill are mirrored in sexual signals

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Perez, C., Munilla, I., Lopez-Alonso, M. & Velando, A. Sublethal effects on seabirds after the Prestige oil-spill are mirrored in sexual signals. Biology Letters 6, 33–35 (2010).

It has been suggested that sexual signals may be a useful measure of environmental quality as they represent the sum of environmental pressures on the animal. Accordingly, it has been proposed that carotenoid-based coloration may be especially valuable in monitoring and detecting the sublethal effects of toxic pollutants in the environment. Here, we evaluate whether the carotenoid-based coloration in the bill of adult yellow-legged gulls reflects oil-induced sublethal effects in breeding colonies affected by the Prestige oil spill. In 2004, we took blood samples from 27 adult birds at four insular breeding colonies located in the pathway of the Prestige oil spill. We measured the size of the red bill spot area and analysed plasma biochemical parameters indicative of sublethal effects of oil contamination in gulls, including glucose, total protein, creatinine, inorganic phosphorus, aspartate aminotransferase (AST) and gamma-glutamyl transferase. We showed that the size of their red bill spot area was positively related to body condition, while negatively related with AST levels, an enzyme that is commonly used as an indication of hepatic damage in birds. Hence, the present study provides support for the idea that carotenoid-based colour integuments may be a useful measure of environmental quality.

Phosphorus in seagull colonies and the effect on the habitats. The case of yellow-legged gulls (Larus michahellis) in the Atlantic Islands National Park (Galicia-NW Spain)

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Otero, X. L. et al. Phosphorus in seagull colonies and the effect on the habitats. The case of yellow-legged gulls (Larus michahellis) in the Atlantic Islands National Park (Galicia-NW Spain). Science of The Total Environment 532, 383–397 (2015).

During the period 1980–2000, the yellow-legged gull population underwent exponential growth due to an increase in the availability of anthropogenic food resources. The aim of this study was to highlight the effect of the gull colonies on the P soil cycle and the associated effects on coastal ecosystems. Samples of soil, water and faecal material were collected in a colony of yellow-legged gulls (Cíes Islands) and in a control area. Four sampling plots were installed in the study areas, and samples were collected in summer and winter in 1997 and 2011. Sample analysis included soil characterization and determination of the total P content (TP), bioavailable-P and fractionated-P forms in the soils and faecal material. The 31P NMR technique was also used to determine organic P forms. Clear differences between the gull colony soils and the control soil were observed. The TP was 3 times higher in the gull colony soil, and the bioavailable P was 30 times higher than in the control soil. The P forms present at highest concentrations in the faecal material (P-apatite, P-residual and P-humic acid) were also present at high concentrations in the colony soil. The absence of any seasonal or annual differences in P concentration indicates that the P has remained stable in the soil over time, regardless of the changes in the gull population density. The degree of P saturation indicated that soils are saturated with P due to the low concentration of Fe/Al-hydroxides, which is consistent with a high P concentration in the run-off from the colonies. The P output from the colony soils to coastal waters may cause eutrophication of a nearby lagoon and the disappearance of a Zostera marina seagrass meadow. Similarly, the enrichment of P concentration in dune system of Muxieiro may induce irreversible changes in the plant communities.

Nitrógeno (NH4+, NO3), fósforo asimilable y metales traza (Hg, Cd, Pb, Zn. Ni y Cu) en suelos de la colonia de la gaviota patiamarilla (Larus cachinnans) en el parque natural de las Islas Cies.

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Otero, X. L. & Mouriño, J. Nitrógeno (NH4+, NO3), fósforo asimilable y metales traza (Hg, Cd, Pb, Zn. Ni y Cu) en suelos de la colonia de la gaviota patiamarilla (Larus cachinnans) en el parque natural de las Islas Cies. Cuadernos de la Sociedad Española de Ciencias Forestales (2002).

La gaviota patiamarilla (Larus cachinnans) presenta en el Parque Natural de las Islas Cíes su mayor colonia de cría con una población aproximada de 20.000 parejas reproductoras. En el presente trabajo se pretende evaluar el efecto que sobre el contenido en nutrientes y metales traza en el suelo puede tener esta colonia. Para ello se seleccionaron tres acantilados en las islas Cíes y una zona control en cabo Home (sin presencia de gaviotas). Los resultados obtenidos han puesto de manifiesto que los suelos de los acantilados de la Percha, zona donde la gaviota patiamarilla lleva criando con densidades elevadas por lo menos desde los años 70, presenta para el nitrógeno, fósforo asimilable y metales traza concentraciones significativamente más elevados que la zona control. Los otros dos acantilados de las islas Cíes (Campana y Figueiras) presentaron, en general, concentraciones intermedias entre las zona control y los suelos de los acantilados de la Percha.

Maternal testosterone influences a begging component that makes fathers work harder in chick provisioning

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Noguera, J. C., Kim, S.-Y. & Velando, A. Maternal testosterone influences a begging component that makes fathers work harder in chick provisioning. Hormones and behavior 64, 19–25 (2013).

In species with biparental care, parents disagree evolutionarily over the amount of care that each of them is willing to provide to offspring. It has recently been hypothesised that females may try to manipulate their mates by modifying offspring begging behaviour through yolk hormone deposition, shifting the division of labour in their own favour. To test this hypothesis we first investigated how yellow-legged gull (Larus michahellis) parents feed offspring in relation to each component of complex begging behaviour and if feeding behaviour varies between sexes. Then we investigated the effect of yolk testosterone on chicks’ begging by experimentally increasing yolk testosterone levels. Our results revealed that yolk testosterone has a component-specific effect on chicks’ begging, specifically increasing the number of chatter calls. Parental feeding effort was influenced by the number of chatter calls emitted by chicks, but most importantly, the influence was stronger in male than in female parents. Moreover, chick body mass increased with the number of paternal feeds. In conclusion, these results show that female gulls may use yolk testosterone deposition to exploit their partners as predicted by the ‘Manipulating Androgen Hypothesis (MAH)’.

Henslow’s swimming crab (Polybius henslowii) as an important food for yellow-legged gulls (Larus cachinnans) in NW Spain

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Munilla, I. Henslow’s swimming crab (Polybius henslowii) as an important food for yellow-legged gulls (Larus cachinnans) in NW Spain. ICES Journal of Marine Science: Journal du Conseil 54, 631–634 (1997).

An analysis of the contents of 2562 pellets sampled from 1987 to 1993 at breeding colonies and roosting sites showed that Henslow’s swimming crabs (Polybius henslowii) are by far the most important marine prey for yellow-legged gulls (Larus cachinnans) on the coasts of Galicia (north-western Spain), occurring in 36.4% of pellets. The results also suggest that yellow-legged gulls in Galicia are to a great extent marine foragers. Galicia has one of the largest yellow-legged gull populations in western Europe, largely dominating the seabird community. Polybius henslowii is the most abundant decapod crab over the continental shelf of Galicia. It enters coastal waters in large shoals and frequently stays close to the sea surface. Compared with the diets of other yellow-legged gull populations or any of the other closely related gull species, such as the herring (L. argentatus) and the lesser black-backed gull (L. fuscus), Polybius henslowii appears as a characteristic and even exclusive prey of yellow-legged gull populations in the Iberian Atlantic. There is also some evidence that the regular irruption of large Polybius henslowii shoals is a phenomenon peculiar to Iberian Atlantic waters.

Desplazamientos de la Gaviota Patiamarilla (Larus cachinnans) en poblaciones del norte de la Península Ibérica

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Munilla, I. Desplazamientos de la Gaviota Patiamarilla (Larus cachinnans) en poblaciones del norte de la Península Ibérica. Ardeola 44, 19–26 (1997).

Se analizan todas las recuperaciones disponibles de gaviotas patiamarillas anilladas como pollos que conciernen al Atlántico norte español (Galicia, Asturias, Cantabria y País Vasco), y se comparan con las recuperaciones de aves anilladas en la provincia de Gerona. Las gaviotas patiamarillas de las colonias del Atlántico norte español no parecen realizar desplazamientos de carácter migratorio, recuperándose la mayoría de las aves a menos de 100 km de la colonia natal, situación que contrasta con el claro comportamiento migratorio de las patiamarillas del Mediterráneo occidental. En las poblaciones del Atlántico se han encontrado diferencias significativas entre clases de edad en las distancias a la colonia natal, correspondiendo los mayores desplazamientos a las aves inmaduras. Por el contrario, los datos de la provincia de Gerona no parecen indicar la existencia de tales diferencias. En ambos casos se observa un marcado ciclo estacional, si bien las menores distancias a la colonia de anillamiento se producen entre mayo y septiembre en el Atlántico, mientras que en Gerona este periodo tiene lugar entre marzo y junio. Por otra parte, los resultados sugieren que las gaviotas del Atlántico norte español constituyen una población cerrada, sin apenas relaciones con otras poblaciones de Larus cachinnans.

Nidificación urbana de Gaviota patiamarilla (Larus cachinnans) en Vigo (Galicia)

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Mouriño, J., Sierra Abraín, F. & Arcos, F. Nidificación urbana de Gaviota patiamarilla (Larus cachinnans) en Vigo (Galicia). Chioglossa 1, 47–52 (1999).

Entre 90 y 120 parejas de Gaviota Patiamarilla (Larus cachinnans) nidificaron en el casco urbano de Vigo en 1989. La colonia se encuentra en el centro de la ciudad. fundamentalmente en casas bajas y antiguas. donde crían en tejados y chimeneas cerradas. El período de puesta coincide con el conocido para las vecinas islas Cíes. concentrándose a primeros de mayo. Las gaviotas habrían colonizado la ciudad alrededor de 1980 a raíz del incremento de la colonia de Cíes. Se prevé que dado el mantenimiento de las favorables condiciones y la abundancia de recursos tróficos. las gaviotas seguirán expandiéndose por la ciudad.

Caracterización de la vegetación de los acantilados del Parque Natural de las Islas Cíes y su relación con la colonia de gaviota patiamarilla (Larus cachinnans)

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Mouriño, J. & Pérez, X. L. O. Caracterización de la vegetación de los acantilados del Parque Natural de las Islas Cíes y su relación con la colonia de gaviota patiamarilla (Larus cachinnans). Cuadernos de la Sociedad Española de Ciencias Forestales 135–142 (2002).

La vegetación característica de los pastos aerohalófilos de Galicia, adscrita a la comunidad Dauco-Festucetum pruinosae, no se encuentra representada en los acantilados estudiados de las islas Cíes. La singularidad en cuanto a la composición florística de estos acantilados, donde son comunes especies pioneras o de marcado carácter nitrófilo (p. ej. Holcus lanatus, Urtica membranacea), está relacionada con la influencia que ejerce la colonia de gaviota patiamarilla (Larus cachinnans) que se estima en unas 20.000 parejas reproductoras. Por otra parte, también se han encontrado importantes cambios en la frecuencia de aparición de ciertas especies tanto a nivel estacional como interanual.

A three-isotope approach to disentangling the diet of a generalist consumer: the yellow-legged gull in northwest Spain

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Moreno, R., Jover, L., Munilla, I., Velando, A. & Sanpera, C. A three-isotope approach to disentangling the diet of a generalist consumer: the yellow-legged gull in northwest Spain. Marine Biology 157, 545–553 (2010).

The widespread omnivory of consumers and the trophic complexity of marine ecosystems make it difficult to infer the feeding ecology of species. The use of stable isotopic analysis plays a crucial role in elucidating trophic interactions. Here we analysed d15N, d13C and d34S in chick feathers, and we used a Bayesian triple-isotope mixing model to reconstruct the diet of a generalist predator, the yellow-legged gull (Larus michahellis) that breeds in the coastal upwelling area off northwest mainland Spain. The mixing model indicated that although chicks from all colonies were fed with a high percentage of fish, there are geographical differences in their diets. While chicks from northern colonies consume higher percentages of earthworms, refuse constitutes a more important source in the diet of chicks from western colonies. The three-isotope mixing model revealed a heterogeneity in foraging habitats that would not have been apparent if only two stable isotopes had been analysed. Moreover, our work highlights the potential of adding d34S for distinguishing not only between terrestrial and marine prey, but also between different marine species such as fish, crabs and mussels.