Population modelling of European shags (Phalacrocorax aristotelis) at their southern limit: conservation implications

Velando, A. and Freire, J., 2002. Population modelling of European shags (Phalacrocorax aristotelis) at their southern limit: conservation implications. Biological Conservation, 107(1), pp.59-69.

The European shag (Phalacrocorax aristotelis) population at Cíes Islands (the most important breeding area in its southern limit) increased rapidly from 1986 to 1992, and afterwards the population suffered a slight decline. This study analyzed population data obtained from ringing recoveries and reproductive monitoring between 1993 and 1997. The reproductive success was highly variable and associated with adverse weather events. Adult survival rate was very low compared with other colonies, probably due to high accidental capture in gill-nets. In recent years, the fishing effort with gill-nets increased in the study area. Sensitivity analysis of parameters showed that the population is more affected by changes in adult survival than in reproductive success. When dynamic simulations were run with an increase in shag mortality of 5% above the present level, population extinction occurred in all simulations. In contrast, when a reduction of mortality of 5% was introduced in the simulations, the population increased in all cases. The main lines of action to study and protect this population should be: (1) ringing schemes to obtain better estimates of survival variability; (2) studies on the interaction of feeding areas and fishing vessels; (3) regulations on gill-netting; and (4) the incorporation of population models as an adaptive management tool to synthesize assessment work and management scenarios.

Coloniabilidad y conservación de aves marinas: el caso del cormorán moñudo

Velando, A. & Freire, J. Coloniabilidad y conservación de aves marinas: el caso del cormorán moñudo. Etología 7, 55–62 (1999).

En el presente trabajo exponemos cómo los estudios de coloniabilidad pueden ser aplicados a la conservación de aves marinas. Los estudios realizados en las Islas Cíes (NO de España) muestran cómo en las colonias del cormorán moñudo (Phalacrocorax aristotelis) existe una atracción de las parejas de baja calidad y/o jóvenes a criar cerca de las de alta calidad. En la Isla de Ons la dinámica espacial de las colonias señala la importancia de la limitación de los sitios de cría, el contexto social y la emigración dependiente de la distancia en los procesos de reclutamiento. Estos estudios nos permiten diseñar criterios de conservación no exclusivamente numéricos. Así para el cormorán moñudo se recomienda la creación de una serie de enclaves protegidos en cadena. También señalan la importancia de la atracción en la restauración de colonias de aves marinas.

Pre-fledgling oxidative damage predicts recruitment in a long-lived bird

Noguera, J. C., Kim, S.-Y. & Velando, A. Pre-fledgling oxidative damage predicts recruitment in a long-lived bird. Biology letters rsbl20110756 (2011).

Empirical evidence has shown that stressful conditions experienced during development may exert long-term negative effects on life-history traits. Although it has been suggested that oxidative stress has long-term effects, little is known about delayed consequences of oxidative stress experienced early in life in fitness-related traits. Here, we tested whether oxidative stress during development has long-term effects on a life-history trait directly related to fitness in three colonies of European shags Phalacrocorax aristotelis. Our results revealed that recruitment probability decreased with oxidative damage during the nestling period; oxidative damage, in turn, was related to the level of antioxidant capacity. Our results suggest a link between oxidative stress during development and survival to adulthood, a key element of population dynamics.