Importance of African Stopover Sites for Migratory Birds After Crossing the Sahara

We investigate the benefits and constraints of migration for birds, specifically the energetic, nutritional, and temporal aspects. Our aim is to then connect these factors to seasonal habitat conditions at stopover sites in Africa. Existing data show the advantages of African sites for nonbreeding birds, but also the risks associated with degradation due to land use changes. The study examines migration ecology jointly with land use patterns to understand the impact on migratory birds and to develop measures that protect convergence sites and the well-being of both birds and humans.

This study focuses on stopover sites and collaboration with partners in South Sudan to analyze the ecology of migrating birds and their associations with habitat patterns. It explores the energetic and trophic aspects of European-breeding birds’ diet at these sites where multiple species overlap. Stable isotope and metabarcoding techniques assess these associations at different scales. We use non-invasive techniques, including sampling of feathers, breath, faeces and blood, to gather data on ecology and body condition at individual, population and species levels.

Bird migration is a challenging journey, especially after crossing the desert, and stopover sites are crucial where birds break from migration to rest and refuel. 30-40% of European songbirds undergo moult at African stopovers. The quality and extent of moult and the ability to continue migration migration depend on resource availability at stopovers. However, if the conditions at these sites are not good, it can affect the birds’ ability to migrate and breed successfully. The protection of these sites is essential to ensuring successful migration and maintaining healthy populations.

Determining origins of birds using feather isoscapes presents challenges for long-distance migratory birds due to the limited availability of validated data. We use stable isotope data from contemporary and archived feathers of both migratory and resident birds to create an isoscape for the Sahel savannah region. We use vegetation, altitude, and rainfall patterns to identify the key variables that influence isoscapes. Our aim is to enhance the precipitation isoscape models and establish a framework for linking feather-to-precipitation data, ultimately refining the feather-based isoscapes.

• University of Juba, South Sudan
• Ministry of Environment, South Sudan
• Museum of Nairobi, Kenya