Infectious diseases are a significant threat to public health, livestock production, and biodiversity conservation. Increasing human population densities, land use change, biodiversity loss, and climate change have accelerated the emergence and spread of new and existing diseases. Free-ranging wildlife populations, particuarly cosmopolitan wildlife species living in human-dominated habitats, act as reservoirs for the spread of disease and are key for predicting current and future disease dynamics. At the same time, wildlife populations in urban areas are often the targets of management actions due to perceived threats to human health, safety, and livelihoods. Since management can alter individual movements, energetic expenditure, and behavior, with effects on wildlife-pathogen interactions, a comprehensive understanding of wildlife-pathogen systems is key to selecting appropriate management actions.
Due to their global distribution and wide-ranging movements, seabirds are important vectors for the spread of pathogens across continents and oceans. Generalist coastal seabirds, which exploit anthropogenic food sources, are particularly likely to interact with zoonotic pathogens, making them useful for monitoring disease prevalence. However, many factors mediating interactions between seabirds and pathogens remain unknown or poorly understood. The effects and duration of early-life exposure may play a key role in later disease states, but the dynamics of developmental exposure are complex. Subsequently, large-scale movement patterns, including migration, dispersal, and foraging, mediate exposure to infectious agents and may vary widely between individuals. Improved understanding of disease exposure across life stages and heterogeneous environments is required to understand disease dynamics in wide-ranging seabirds.
Our study combined field study, laboratory analysis, and modeling to explore prevalence and transmission of zoonotic pathogens by brown skuas (Stercorarius antarcticus) and yellow-legged gulls (Larus michahellis), two scavenging and predatory seabirds that forage in marine and terrestrial environments and nest among other marine birds, making them key reservoirs for diease transmission and spread to avian and human populations. These complementary studies allowed us to describe exposure pathways and probabilities across individuals and life stages, evaluate spatial dynamics of adults, assess potential effects of management on local disease circulation, and develop guidelines for management and monitoring.
