Understanding food selection of migratory birds during stop-over and wintering

The overarching aim of this project is to determine the arthropod and plant species consumed by migratory species in their non-breeding grounds.

Our project has the following objectives:

1. Quantify diet composition and food selection of migratory songbird species in their non-breeding grounds, across space and time.
2. Assess potential nutritional bottlenecks of migratory birds, where they may be most vulnerable to changes in food availability.
3. Compare the diets of migrant and co-habiting resident species to understand specific requirements of the migratory lifestyle.

This project involves a network of 8 sites across the non-breeding grounds of migratory birds, at which mist-netting surveys are being conducted. Collaborators at these sites collect faecal samples which we then analyse at the Swiss Ornithological Institute using diet metabarcoding. This method extracts and identifies DNA from food items (insects, plants) found in faecal samples. At each field site, surveys are conducted to quantify food availability. Our study focusses on five species groups: warblers, nightingales, chats, shrikes and flycatchers, each of which encompasses several species.

Given the continuous land-use intensification and rapid climatic changes occurring in Africa, it is important to understand the potential consequences for birds to put in place effective conservation plans. Diets on the flyway will generate novel data on the ecology of migratory birds, allowing us to answer questions regarding the dietary signature of the migratory lifestyle, and to estimate the vulnerability of migratory species across space and time. These findings will stimulate follow-up studies that identify management and restoration measures that will contribute to species conservation.

Preliminary results thus far have demonstrated that the metabarcoding methods are suitable to study migrant diets. We found evidence of diet similarities within bird species groups (e.g., wheatears, warblers), and also some site-specific trends such as lower diet diversity in a desert stop-over site when compared to a savanna habitat. Preliminary data also provided an insight into a curious behaviour: Woodchat shrikes eat engorged camel ticks during spring migration stop-over in Morocco.

• Ivan Maggini, Marc Illa & Yasmina team (Mo-rocco)
• Oliver Fox & Kartong Bird Observatory (The Gambia)
• Chima Nwaogu, Will Cresswell & A. P. Leventis Ornithological Institute (Nigeria)
• Clément Daboné (Burkina Faso)
• John Musina (National Museums of Kenya, Kenya)
• Simon Gift (South Sudan)
• Mathieu Mahamoud-Issa (Djibouti)
• Yosef Kiat & lab (Israel)

• SNSF COST Action grant
• EUFLYNET COST Action