alterado para: Farmland bird responses to human-driven environmental  changes”. Forecasting the impacts of climate and land-use changes on Mediterranean farmland birds

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Farmland Bird responses to human-driven environmental changes

Publication . Marcelino, Joana Lopes; Catry, Inês; Moreira, Francisco Manuel Ribeiro Ferraria; Rego, Francisco Manuel Cardoso Castro

Human-driven environmental changes are shaping habitats and impacting biological communities worldwide, harming biodiversity and disrupting ecosystems' functions. Understanding the impacts and fitness consequences of multiple stressors on wildlife is key to halting this biodiversity crisis. This thesis addresses the mechanisms through which anthropogenic activities influence the population dynamics of migratory farmland birds. Long-distance migrants are pioneer indicators of both habitat and climate changes, as they show fast responses to disturbance and must deal with regional cumulative effects throughout the annual cycle. This thesis focuses on the lesser kestrel (Falco naumanni) and the white stork (Ciconia ciconia), two species with a strong association with man. These model species were used to understand the impacts of climate change in two climatic hotspots - the Mediterranean region and the Sahelian belt - on the breeding performance and movement behaviour of birds and the impacts of human infrastructures (power lines and landfills) on their movement patterns and migratory strategies. In a study on the impacts of forecasted climate change and extreme climatic events on lesser kestrels'breeding performance, we show that while forecasted productivity did not change with the forecasted changing climate, extreme droughts significantly lowered breeding success. By identifying the global drivers of white storks' flight altitudes and their flight behaviour near power lines, we show that collision risk increases during crepuscular hours, on days with high cloud cover density, and during the breeding season, and that landfill sites (that concentrate high densities of storks) are high-risk areas for collision. When investigating the influence of landfills as stopovers on the migratory behaviour of white storks, we found that although foraging in landfills allows birds in poor body condition to survive the migration, they also promote late arrivals at the Sahel, with cascading consequences on survival and population dynamics. Finally, we tried to understand how white storks cope with Moreau's paradox under the current climate, finding that they handle changes in climate and in forage availability by gradually moving southwards as the vegetation dries out, and if the vegetation dries out too quickly, they advance their spring migration. Overall, this thesis provides evidence of the impacts of human-driven environmental changes on farmland migratory birds. This is crucial to allow conservation measures to be taken to reduce conflicts between birds and a human-dominated environment, a balance which pictures itself as a daunting challenge.

2023-10-18Doctoral thesis

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Anthropogenic food subsidies reshape the migratory behaviour of a long-distance migrant

Publication . Marcelino, J.; Franco, A.M.A.; Acácio, M.; Soriano-Redondo, A.; Moreira, F.; Catry, I.

Bird migratory journeys are often long and hostile, requiring high energetic expenditure, and thus forcing birds to pause between migratory flights. Stopover sites allow migrants to replenish fuel reserves and rest, being crucial for the success of migration. Worldwide, the increasing accumulation of waste on landfills and rubbish dumps has been described to provide superabundant food resources for many bird species not only during the breeding and wintering seasons but also during migration, being used as stopover sites. Using GPS-tracking data of juvenile white storks (Ciconia ciconia) during their first migration from the Iberia Peninsula to the sub-Saharan wintering grounds, we uncover the effects of stopping en route on individual migratory perfor- mance. Particularly, we examine the benefits of stopping at artificial sites (landfills and rubbish dumps) when com- pared to natural stopover sites (wetlands, agricultural or desert areas) and explore the influence of anthropogenic food resources on storks' migratory strategies. Overall, white storks spent up to one-third of the migration in stopovers. We found that birds that stopped for longer periods made more detours, increasing migration duration by half a day for each stopover day. Stopping more often did not reflect on increasing in-flight energetic efficiency nor the likelihood of completing the migration. Juvenile storks used artificial sites in 80 % of the stopover days, spending 45 % less time and 10 % less energy foraging than when using natural stopovers. While stopping in landfills did not translate into differences in migratory

2023-02Journal article

Open access