Investigating the ecological mechanisms and consequences of spatial movements of an opportunistic predator

Species: Yellow-legged Gull

View of the wetland (Odiel, Spain) where the breeding colony of yellow-legged gulls is located.

Human activities are impacting ecosystems globally, to an unprecedented degree and with important effects on global biodiversity. However, human activities do not affect all species in the same way and environments transformed by human development may still provide profitable habitats and resources for species with a moderate degree of adaptation to anthropogenic alterations. Population expansions related with human disturbances have recently gained notoriety as a major conservation and management concern in natural and semi-natural ecosystems. However, the mechanisms that facilitate the invasion or proliferation of native species and the ecological consequences of this expansion have been scarcely studied.

Attachment of UvA-BiTS logger in an adult yellow-legged gull.

In this project, we are investigating the main ecological factors and repercussions related to the success and expansion of the yellow-legged gull (Larus Michahellis), species model of an ecological ‘winner’ and successful marine predator adapted to human-transformation. Particularly, we are examining; (i) the degree of individual specialization in foraging habits, (ii) the type of habitat exploited when searching for food; (iii) interactions with other species coexisting in the same area; (iv) the main trophic habits and the relationships between spatial use and (vi) physiological state and (vii) pathogens prevalence. To meet these objectives, we will use a multidisciplinary fieldwork and laboratory approach combining the use of high-resolution UvaBits devices, intrinsic markers, ecophysiological parameters and pathogen screening.
During the incubation period of 2015, we are deploying UvA-BiTS loggers on 30 breeding adult gulls belonging 15 breeding pairs. Main spatial and foraging descriptors of each tracked-individual will be linked to specific physiological parameters measured in blood samples, and also pathogen prevalence. We will also analyse stable isotopes in blood and feathers to relate spatial movements, ecophysiology and pathogen load with the derived trophic niche of each individual.

Releasing a yellow-legged gull with the UvA-BiTS logger

Capturing one adult of yellow-legged gull with a nest-trap.

Contact Persons:

Joan Navarro, and Manuela G. Forero                         Estación Biológica de Doñana EBD-CSIC, Sevilla (Spain)

Willem Bouten, Universiteit van Amsterdam




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