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Demographic rates such as recruitment and survival probability can vary considerably among populations of the same species due to variation in underlying environmental processes. If environmental processes are spatially correlated, nearby populations are expected to have more similar demographic rates than those further apart. Breeding populations and foraging ranges are spatially segregated in colonial seabirds, making them ideal for studying spatial patterns in demographic rates and their effects on local population dynamics. Here we explored variation in age-dependentsurvival probabilities across 14 colonies of Herring Gulls Larus argentatus breeding along the Dutch North Sea coast. We used long-term mark–recapture data of marked fledglings to estimate survival, and estimated spatial autocorrelation of survival probabilities. We assessed whether survival until recruitment age or until 10 years old (close to their expected lifespan) explained variation in population trajectories of each colony. Juvenile and adult survival showed a strong, but different, north-to-south gradient in survival probability, with lower juvenile but higher adult survival in northern colonies than southern colonies, whereas the spatial pattern of immature survival was less distinct. Neither recruitment nor the proportion of 10-year-old adults alive predicted whether a colony collapsed, declined, remained stable or increased. The distinct spatial pattern in survival suggests variation in regional food availability, which do not seem to drive local population dynamics. The absence of a link between survival and colony trajectories implies that connectivity between populations plays an important role affecting population dynamics.

Breeding success of many Arctic-breedingbird populations varies with lemming cycles dueto prey switching behavior of generalist predators. Several bird species breed on islands to escape fromgeneralist predators like Arctic fox Vulpes lagopus, but little is known about how these species interact.We studied brent geese Branta bernicla bernicla that share islands with gulls (Larus spec.) in Taimyr, Siberia(Russia). On one hand, gulls are egg predators, which occasionally steal an egg when incubatinggeese leave the nest for foraging bouts. On the other hand, gulls import marine resources to the islands,enriching the soil with their guano. We considered three hypotheses regarding clutch size of brent geeseafter partial nest predation. According to the “predator proximity hypothesis”, clutch size is expected tobe smallest close to gulls, because of enhanced predator exposure. Conversely, clutch size is expected tobe largest close to gulls, because of the supposedly better feeding conditions close to gulls, which mightreduce nest recess times of geese and hence egg predation risk (“guano hypothesis”). Furthermore, gullsmay defend their nesting territory, and thus nearby goose nests might benefit from this protection againstother gulls (“nest association hypothesis”). We mapped goose and gull nests toward the end of the gooseincubation period. In accordance with the latter two hypotheses, goose clutch size decreased with distanceto the nearest gull nest in all but the lemming peak year. In the lemming peak year, clutch size wasconsistently high, indicating that partial nest predation was nearly absent. By mapping food quantity andquality, we found that nitrogen availability was indeed higher closer to gull nests, reflecting guanofication.Unlike predicted by the nest association hypothesis, a predation pressure experiment revealed thategg predationrate decreased with distance to the focal gull nests. We therefore propose that higher food

Breeding success of many Arctic-breedingbird populations varies with lemming cycles dueto prey switching behavior of generalist predators. Several bird species breed on islands to escape fromgeneralist predators like Arctic fox Vulpes lagopus, but little is known about how these species interact.We studied brent geese Branta bernicla bernicla that share islands with gulls (Larus spec.) in Taimyr, Siberia(Russia). On one hand, gulls are egg predators, which occasionally steal an egg when incubatinggeese leave the nest for foraging bouts. On the other hand, gulls import marine resources to the islands,enriching the soil with their guano. We considered three hypotheses regarding clutch size of brent geeseafter partial nest predation. According to the “predator proximity hypothesis”, clutch size is expected tobe smallest close to gulls, because of enhanced predator exposure. Conversely, clutch size is expected tobe largest close to gulls, because of the supposedly better feeding conditions close to gulls, which mightreduce nest recess times of geese and hence egg predation risk (“guano hypothesis”). Furthermore, gullsmay defend their nesting territory, and thus nearby goose nests might benefit from this protection againstother gulls (“nest association hypothesis”). We mapped goose and gull nests toward the end of the gooseincubation period. In accordance with the latter two hypotheses, goose clutch size decreased with distanceto the nearest gull nest in all but the lemming peak year. In the lemming peak year, clutch size wasconsistently high, indicating that partial nest predation was nearly absent. By mapping food quantity andquality, we found that nitrogen availability was indeed higher closer to gull nests, reflecting guanofication.Unlike predicted by the nest association hypothesis, a predation pressure experiment revealed thategg predationrate decreased with distance to the focal gull nests. We therefore propose that higher food

Introductie en rasbeschrijving van de Anatolische meeuw en de Duitse kleurstaartmeeuw

Utah Division of Wildlife Resources photo of a California gull sitting on the water.

Utah Division of Wildlife Resources photo of Franklin's gulls sitting on the water with white-faced ibis in the grassy area behind.

Utah Division of Wildlife Resources photo of a California gull sitting on the water.

Utah Division of Wildlife Resources photo of Franklin's gulls sitting on the water with white-faced ibis in the grassy area behind.

The current work shows the first step in the knowledge on the health status of European storm petrel (Hydrobates pelagicus) colony inhabiting Grosa Island (Murcia, SE Spain). We performed a screening about the bacterial pathogens carried by them (among the infectious agents checked, bacteria of the orders Mollicutes and Chlamydiales, and the genera Salmonella are of main interest) and compare these results with similar works performed in Larus species because most of the breeding colonies of storm petrel share habitats with gull colonies, and these could become pathogen reservoirs to petrels. Our results show the European storm petrels sampled have absence of pathogens of main interest and low levels of opportunistic pathogens. No Mycoplasma species were isolated, and no Chlamydophila psittaci were demonstrated by lipopolysaccharide antigen immunodetection. The commensal bacteria were isolated in higher frequencies than the previous [Staphylococcus epidermidis (5/15), Staphylococcus hominis (2/15) and Staphylococcus aureus (1/15)]. The rate of isolation of Gram-negative was lower than in the previous Gram-positive bacteria [Pasteurella sp. (1/15) and Pseudomonas aeruginosa (1/15)], and no Enterobacteriaceae were isolated. The absence of pathogen carriers on European storm petrel is the main conclusion of this survey; it is an evidence that the bacterial infectious pathogens described in gulls may not be an important selective force on their survival.

Kleine mantelmeeuwen (Larus graellsii) hebben zich in 1926 als broedvogel in Nederland gevestigd. Zij halen hun voedsel voornamelijk van zee en eten verschillende soorten zeevis en zwemkrabben. De afgelopen jaren hebben zich steeds meer vogels in het binnenland gevestigd. Zij blijken daar voornamelijk weidevogels, zoogdieren en menselijke voedselresten te eten. Aldus conclusies uit NIOZ onderzoek

We studied the determinants of colony site dynamics in Audouin's gull, Larus audouinii, breeding in a small archipelago of the western Mediterranean. Data on island occupation were available for a series of 25 years, since first colonization of the archipelago in 1973. Group behavior was studied in relation to the components of dispersal: permanence or abandonment (extinction) on an island previously occupied and permanence or occupation (colonization) of another island. Generalized Linear Mixed Models (GLMMs) were used to identify the relative contribution of each explanatory variable to the probability of colony abandonment. Gulls showed a low probability (3%) of abandoning one of the islands (Grossa I.), especially when the colony was increasing in numbers from time ti-1 to ti. However, the probability of abandoning Grossa increased up to 31% when the colony was declining. The probability of island abandonment was very high for all other islands (range 66-99%) when the colony was declining, but much lower (range 36-82%) when it was increasing. Hence, we suggest that island abandonment by Audouin's gull is at least a two-step process. The first step (dispersal of a portion of the colony) probably takes place at random, as an evolutionary load typical of a species evolved in unstable habitats. The second step, a further loss of breeding pairs, seems to feedback on the first loss of members of the colony (public information), likely perceived as a loss of colony quality. Colonization of islands by gulls abandoning Grossa I. was marginally and negatively affected by the density of breeding yellow-legged gulls, a predatory species. Results apply to conservation ecology since they highlight the need to protect not only occupied patches but also those empty at present.

Verslag van onderzoek naar de invloed van twee lijnopstellingen van windturbines (Slag Dobbelsteen en Slufterdam) op de voedselvluchten van meeuwen (vnl. kleine mantelmeeuw, Larus graellsii, en zilvermeeuw, L. argentatus) en sterns (vnl. visdief, Sterna hirundo) tussen de broedkolonies op de Maasvlakte en de foerageergebieden op zee. De waarnemingen betroffen het dagelijkse patroon van de voedseltochten, de vlieghoogte en de reactie van de vogels bij het kruisen van de windturbines. De meeste vogels bleken de lijnopstellingen op windturbinehoogte te passeren zonder zich er iets van aan te trekken