In the Mediterranean, the survival of endemic long-lived seabirds despite the long-standing introduction of one of the most damaging alien predator, the ship rat (Rattus rattus), on most islands constitutes an amazing conservation paradox. A database gathering information on approximately 300 Western Mediterranean islands was analyzed through generalized linear models to identify the factors likely to influence ship rat presence and to account for how ship rat presence and island characteristics may have driven the presence and abundance of seabirds. Our review showed that few Mediterranean islands remain rat-free. At the regional scale, rat presence was only a limiting factor in the abundance of the smallest seabird, the storm petrel (Hydrobates pelagicus), while the distribution and abundance of the three shearwaters were more influenced by island characteristics. We hypothesized that the long-term persistence of these seabirds may have been facilitated by the various biogeographical contexts of Mediterranean islands, likely to provide intra-island refuges.
Summary1. Contrary to the generally high level of natal philopatry (i.e. likelihood that individuals breed at their natal colony) found in first-breeding colonial birds, little is known of natal philopatry later in life. Most hypotheses advanced to explain natal philopatry are valid at all ages. However, for young and inexperienced birds, the benefits of natal philopatry may be counterbalanced by the costs of intraspecific competition at the natal colony making dispersal temporarily advantageous. In turn, experience may increase competitive ability and make natal philopatry advantageous again. 2. We evaluated this hypothesis on the large-scale dispersal of greater flamingos Phoenicopterus roseus breeding among three colonies comprising >85% of the Western Mediterranean metapopulation. The Camargue (France) and Fuente de Piedra (Spain) are large and saturated colonies while Molentargius (Sardinia) is a recent and growing colony. 3. We used a 20-year capture-mark-resighting dataset of 4900 flamingos ringed as chicks in Camargue and Fuente de Piedra and breeding at the three colonies. We assessed the effects of natal colony and breeding experience (first-time observed breeders versus confirmed experienced breeders) on dispersal using multistate capture-recapture models. Dispersal to an unobservable state accounted for temporary emigration. 4. Fidelity was higher at the natal colony (>84%) than elsewhere. Fidelity increased with experience in the two large colonies (Camargue and Fuente de Piedra) suggesting a large-scale experience-related despotic distribution. Breeding dispersal was significant (up to 61% and 52% for firsttime breeders and experienced breeders, respectively) so that colony dynamics is affected by exchanges with other colonies. Except for Fuente-born breeders leaving Molentargius, dispersal to the natal colony was higher than to any other colonies. 5. Survival was not higher at the natal colony. Inexperienced birds likely had lower breeding success at the Camargue and skipped reproduction after having emigrated to the other large colony but not to Molentargius. Breeding at Molentargius could allow avoiding queuing (and non-breeding) at the large colonies while gaining experience and competitive ability for future attempts. 6. Natal philopatry appears as an important driver of large-scale breeding dispersal in the Greater flamingo. The fitness advantage of natal philopatry is likely experience-dependent and mediated by the variations of intraspecific competition.
SUMMARY: A country-by-country review of seabird mortality from longline fishing in the Mediterranean Sea and in Macaronesian waters shows a paucity of data. Of 12 Mediterranean countries known to undertake longlining, seabird mortality is only reported for six: France, Greece, Italy, Malta, Spain and Tunisia. Seabird mortality from longlining has been reported from the Azores (Portugal) but not from the other Macaronesian Islands. Only for one country, Spain, is information on the levels of mortality available, suggesting that 4-6% of the local breeding population of Cory's shearwater Calonectris diomedea may be killed annually, a level considered unsustainable for the long-term persistence of colonies. Cory's shearwater is the most commonly affected species, although a number of Larus gull species are also being caught. There is insufficient knowledge to conclude whether any seabird species is at conservation risk within the region, but concern is expressed for Cory's shearwater. It is recommended that Mediterranean and Macaronesian countries conduct assessments of their longline fisheries and seabird mortality in terms of the Food and Agriculture Organization's International Plan of ActionSeabirds. Regional fishery organisations, such as ICCAT and GFCM, should commence the collection of seabird mortality data. A "longline action plan" for the affected seabird species should be produced.Key words: seabirds, longline fishing, conservation, Mediterranean, Macaronesia. RESUMEN: MORTALIDAD DE AVES MARINAS EN PALANGRES DEL MAR MEDITERRÁNEO E ISLAS MACARONESIAS: REVISIÓN Y PRO-PUESTAS DEFUTURO. -Este trabajo presenta una revisión de la escasa información disponible sobre mortalidad de aves marinas en las flotas palangreras del mar Mediterráneo y Macaronesia. De los 12 países mediterráneos que disponen de flota palangrera tan sólo 6 han aportado información sobre mortalidad de aves marinas: Francia, Grecia, Italia, Malta, España y Túnez. También se sabe que existe mortalidad de aves marinas en las islas Azores (Portugal) pero no en el resto de las islas de la Macaronesia. Tan sólo España dispone de información sobre niveles de mortalidad. Es posible que entre el 4-6% de la población reproductora local de pardela cenicienta Calonectris diomedea muera en el palangre anualmente, un nivel que se considera insostenible para la persistencia a largo plazo de las colonias. La pardela cenicienta es la especie más afectada, aunque también se capturan gaviotas del género Larus. Aunque no se sabe lo suficiente como para concluir si alguna especie de ave marina está amenazada localmente por el palangre, se sugiere que la pardela cenicienta sí puede estarlo. Se recomienda que los países mediterráneos y macaronésicos lleven a cabo valoraciones de sus pesquerías de palangre y de la mortalidad de aves marinas en los términos de los planes internacionales de acción de la FAO. Las organizaciones pesqueras
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