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Gulls, as largely flexible opportunistic individuals, have been increasingly breeding in many cities around the world, but it is still unclear whether urban habitats are of equal or higher quality than traditional natural habitats or represent an ecological trap with immediate reproductive benefits but longer‐term detrimental consequences to health. Here we present a study of breeding parameters (nest density, egg dimensions, clutch size, hatching success and adult body condition) and physiological parameters (erythrocyte sedimentation rate, heterophil/lymphocyte ratio, haemoglobin concentration and measurements of oxidative stress) as indicators of the general health condition of Yellow‐legged Gull Larus michahellis adults and chicks from natural and urban colonies. Yellow‐legged Gulls in the largest urban area (Porto) laid smaller eggs and clutches, showed a significantly lower occurrence of inflammatory processes in chicks, and showed a slower early chick growth than in the natural colony of Deserta. This suggests that urban gulls might be facing important trade‐offs between the advantages of breeding in lower density urban colonies, with fewer intraspecific interactions and a lower disease transmission probability, and the disadvantages of having an anthropogenic diet usually lower in nutritional value. [ABSTRACT FROM AUTHOR]

A detailed analysis of fatty acid (FA) profiles and their properties relating to fuelling strategy can improve understanding of avian migration. The study aimed to understand whether and how FA composition differs among several passerine species which migrate using different fuelling strategies (constant fuelling, gradual fuelling, early fuelling or late fuelling). We found evidence for differential FA composition among migratory species according to their fuelling strategies: early fuellers presented higher n‐3 polyunsaturated FA and gradual fuellers higher mono‐unsaturated FA, which can be directly related to their differential migratory strategies to maximize energy use. [ABSTRACT FROM AUTHOR]

Both intrinsic and extrinsic factors recorded at individual nests can predict offspring fitness and survival but few studies have examined these effects in the tropics. We recorded nestling survival, post-fledging survival and age at first return of Roseate Terns breeding at Aride Island, Seychelles, over a 12-year period (1998-2009). Nest data recorded at the egg, nestling and fledging stages were collected during six breeding seasons (1998, 2001-2005) and a capture-mark-recapture dataset of six cohorts of fledglings was obtained from 2001-2009. Logistic regression models were used to assess the predictive effect of reproductive variables on fledging success, while multistate capture-mark-recapture models were used to estimate post-fledging survival and return-recruitment probabilities to the natal site. Nestling survival probability increased with earliness of laying and was negatively affected by tick infestation during the growth period (0-23 days). Fledging probability was also positively related to chick body condition, whereas other pre-fledging reproductive parameters such as clutch size and egg size were not influential. A multistate modelling of age-specific survival and return-recruitment (transition) rates found that first-year survival differed between cohorts and was also negatively affected by tick infestation. Annual survival stabilized from age 2 onwards at 0.83 ± 0.02. Transition rates were positively related to body condition at fledging, with heavier individuals returning for the first time to the natal colony at a younger age compared with lighter individuals. These results highlight the importance of local conditions encountered by tropical seabirds during the breeding season in shaping demographic parameters. [ABSTRACT FROM AUTHOR]

Seed dispersal is a central process in plant ecology with consequences for species composition and habitat structure. Some bird species are known to disperse the seeds they ingest, whereas others, termed 'seed predators', digest them and apparently play no part in dispersal, but it is not clear if these are discrete strategies or simply the ends of a continuum. We assessed dispersal effectiveness by combining analysis of faecal samples and bird density. The droppings of seed dispersers contained more entire seeds than those of typical seed predators, but over a quarter of the droppings of seed predators contained whole seeds. This effect was further magnified when bird density was taken into account, and was driven largely by one frequent interaction: the Chaffinch Fringilla coelebs, a typical seed predator and the most abundant bird species in the area and dispersed seeds of Leycesteria formosa, a non-native plant with berry-like fruits. These results suggest the existence of a continuum between seed predators and seed dispersers. [ABSTRACT FROM AUTHOR]

We assessed the effects of environmental variables on the distribution and feeding behaviour of adult Little Terns Sternula albifrons in Ria Formosa Natural Park, Algarve, southern Portugal, in different foraging habitats (main lagoon, salinas and sea) during the breeding seasons, April–July, of 2003–05. Foraging density was higher in the lagoon than in the sea, and at low tide. The number of foraging individuals at sea was independent of tide. Individual Little Terns foraged further from the nearest breeding colony in April and May (courtship feeding and incubation) than in June and July (chick-rearing). During intermediate tidal phases, individuals foraged further from the nearest colony, and followed main lagoon channels, perhaps because stronger currents increased prey availability. Diving activity and foraging success were higher in 2003 than 2004 or 2005, perhaps because of greater availability of marine prey in 2003. Diving rate was higher in July (when independent juveniles began learning how to forage) but diving success was higher in June (chick-rearing) than in other months. The variables selected by the final logistic models reflected four basic needs for the selection of feeding habitats by Little Terns: (1) association between foraging individuals, (2) areas with abundant feeding resources, (3) entrance channels and main lagoon channels with strong currents, and (4) the proximity to areas with alternative feeding resources, the salinas. Areas subjected to strong human pressure were avoided by foraging Little Terns. [ABSTRACT FROM AUTHOR]

This paper describes the breeding population, breeding habitats and reproductive variables of Little TernsSterna albifronsin natural (sandy beaches) and alternative (salinas) habitats. Studies of nesting success conducted between 1998 and 2002 in these two types of habitat were combined with a literature review of census work from the past 30 years in order to assess whether salinas are suitable alternative breeding habitat for Little Terns. Most of the Portuguese Little Tern population now breeds in salinas. Census data from the last 30 years show that this is a recent breeding behaviour, because until the 1990s most colonies were located on sandy beaches. Destruction and disturbance of the natural habitat has caused this habitat shift. Despite this shift, the Portuguese Little Tern breeding population did not decline during this period and no significant differences were found in nesting success between natural and alternative habitats. This might indicate that salinas are a suitable alternative breeding habitat for Little Terns, but differences in laying period, clutch size and egg size were recorded between birds nesting on sandy beaches and in salinas in the same area. Birds nested earlier on sandy beaches and laid larger clutches and eggs than in salinas. These data suggest that, when both habitats are available, older and/or higher quality birds prefer sandy beaches for breeding, presumably trying to re-nest in salinas when first breeding attempts failed. We discuss conservation priorities and management actions for both habitats. [ABSTRACT FROM AUTHOR]