Effect of Age, Colony of Origin and Year on Survival of Yellow-Legged Gulls Larus michahellis in the Bay of Biscay

Juez, L.; Aldalur, Asier; Herrero, Alfredo; Galarza, Aitor; Arizaga, Juan

doi:10.13157/arla.62.1.2015.139

Cited by 16 publications

(11 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The colony size trend was found to be unclear, probably stable or showing a moderate decrease (Arizaga et al 2014). Survival values vary from year to year, with firstyear birds having a mean annual survival of 0.4-0.6, while adults have a mean annual survival rate of 0.8-0.9 (Juez et al 2015). Chick diet also varies from year to year; during the period 2007-09 they were assessed to feed on marine prey (approximately 40%), garbage (approximately 40%) or invertebrates of terrestrial origin (approximately 20%) (Arizaga et al 2013).…”

Section: Sampling Site and Protocolmentioning

confidence: 99%

Sex differences in growth rates of Yellow-legged Gull Larus michahellis chicks

Jordi

Arizaga

2016

Bird Study

Self Cite

View full text Add to dashboard Cite

Capsule: Chick growth rates was sex-dependent in an Atlantic Yellow-legged Gull Larus michahellis population. Aims: To describe the growth rate of Yellow-legged Gull chicks and sex-associated variations, and obtain a discriminant function to sex them using morphological data. Methods: Fifty-two Yellow-legged Gull chicks from a colony in northern Iberia were measured for body mass, head and bill length, tarsus length and three other bill-length associated variables, from the hatching date up to the age of 36 days. Birds were sexed using DNA analysis. Results: Using logistic models, chick growth rates was observed to be similar between the sexes, while the asymptote was higher among males for the majority of the variables. Discriminant analyses showed that the variable head+bill was very reliable to predict the sex of >80% of chicks at an early developmental stage, and 100% of chicks if combined with tarsus length and two more bill-length associated variables at the age of 35 days. Conclusions: This is the first study using a discriminant analysis to sex Yellow-legged Gull chicks, and also the first to describe the growth function for the species. The growth rate varied between sexes because males showed higher asymptote values within the growth function. ARTICLE HISTORY

show abstract

Section: Sampling Site and Protocolmentioning

confidence: 99%

Sex differences in growth rates of Yellow-legged Gull Larus michahellis chicks

Jordi

Arizaga

2016

Bird Study

Self Cite

View full text Add to dashboard Cite

show abstract

“…Aún así, para un periodo de monitorización inferior a 4 meses, ya disponemos de muchos más datos por ejemplar que mediante el uso de anillas de color (Arizaga et al, 2010;Juez et al, 2015).…”

Section: Discussionunclassified

Uso del espacio por adultos de gaviota patiamarilla Larus michahellis Naumann, 1840 durante el periodo reproductor: resultados preliminares en relación al uso de vertederos.

Arizaga¹,

Laso²,

Zorrozua³

et al. 2017

Munibe, Cienc. nat.

Self Cite

View full text Add to dashboard Cite

ResumenEn la actualidad, con el progresivo cierre de vertederos, nos situamos en un marco experimental ideal para estudiar cómo afecta la reducción drástica de un recurso trófico en la ecología, dinámica poblacional y movimientos de una especie con alto interés en la gestión, como es la gaviota patiamarilla Larus michahellis Naumann, 1840. En este contexto, en 2016 se equiparon con GPS un total de 10 ejemplares adultos de gaviota patiamarilla en una de las colonias de cría de Gipuzkoa, de los que sólo 4 proporcionaron datos hasta el 31.07.2016. El análisis preliminar aporta información básica sobre el uso del territorio durante una parte del periodo reproductor. El porcentaje de localizaciones se distribuyó de esta manera: 60% en la colonia; 18% en otro tipo de hábitats; 12% en prados y cultivos; y 6.5% en vertederos. Se detecta, así, un relativo alto uso de los prados y cultivos del entorno de la colonia, así como de dos de los vertederos más importantes de la región. Por otro lado, parece existir alta variabilidad individual en el uso del territorio que podría reflejar diferentes estrategias en la búsqueda de alimento.Palabras clave: Dispositivos GPS, ecología espacial, especies oportunistas, Gipuzkoa, vertederos. AbstractToday, the progressive closure of landfills provides a good opportunity to study how this affects the drastic reduction of a food resource on the ecology, population dynamics and movement patterns of opportunistic species, such as the yellow-legged gull Larus michahellis Naumann, 1840. Against this background, in 2016, we captured 10 adult breeding gulls in one of the main breeding colonies in Gipuzkoa. These individuals were equipped with a GPS device. Only four of them provided data up to the end of the breeding period (31.07.2016). Preliminary analyses provide basic information about spatial use and trophic habitat during the breeding period (colony: 60%; other habitat types: 18%; grasslands/crops: 12%; dumps: 6,5%). An apparently relatively high use of grasslands and crops is confirmed, as well as the use of two of the largest landfills in the region. We also observed a very high individual variation in territory use, which might reflect different foraging strategies.Key words: GPS device, spatial ecology, opportunistic species, Gipuzkoa, dumps. LaburpenaEgun, urratsez urrats zabortegiak ixten ari direlarik, testuinguru esperimental ezin hobean gaude ikertzeko nola eragiten dion baliabide trofiko baten erabateko murrizketak maila ekologikoan, populazio dinamikan eta mugimenduetan, baliabide horren kudeaketarekin lotura handia duen kaio hankahoriari, Larus michahellis Naumann, 1840.

show abstract

“…All the colonies are situated in marine cliffs of similar characteristics. The population at Getaria and Santa Clara has an uncertain trend (possibly stable), while the one at Ulia is estimated to be in decline [12].…”

Section: Sampling Areamentioning

confidence: 99%

Between the Land and Sea: How Yellow-Legged Gulls Have Changed Their Dependence on Marine Food in Relation to Landfill Management

Arizaga¹,

Zorrozua²,

Egunez³

2018

Seabirds

Self Cite

View full text Add to dashboard Cite

The Basque region (Spain) is closing all its open-air landfills, which hence provides an excellent chance to account for the effects on the trophic and spatial ecology of the local yellow-legged gulls Larus michahellis, which highly depend on refuse tips to forage. The closure of several landfills across the region was mainly compensated by a higher intake of terrestrial food (mainly earthworms), though only in summer. The exploitation of terrestrial prey was marginal in winter, and seasonal trophic differences emerged, unlike findings when landfills were still open. With only one landfill now open in theory, movement and territory use analyses showed that two landfills were frequently visited. Positions at two of the target foraging habitats (landfills, pastures) summed ca. 10% of all stationary positions suggesting that, at least in these habitats, gulls seemed to invest a relatively small amount of time, which might support the idea that they were able to obtain food in a fast way and, probably, from resources that they know well and have a predictable temporal distribution.

show abstract

Effect of Age, Colony of Origin and Year on Survival of Yellow-Legged Gulls Larus michahellis in the Bay of Biscay

Cited by 16 publications

References 32 publications

Sex differences in growth rates of Yellow-legged Gull Larus michahellis chicks

Sex differences in growth rates of Yellow-legged Gull Larus michahellis chicks

Uso del espacio por adultos de gaviota patiamarilla Larus michahellis Naumann, 1840 durante el periodo reproductor: resultados preliminares en relación al uso de vertederos.

Between the Land and Sea: How Yellow-Legged Gulls Have Changed Their Dependence on Marine Food in Relation to Landfill Management

Contact Info

Product

Resources

About