Human–wildlife interactions on the tidal flats of the Bijagós Archipelago: does shellfishing affect migratory shorebirds?

The Bijagós Archipelago in West Africa is home to an ethnic group with a rich cultural heritage that is tightly linked to nature. The Bijagós people have a shared cultural identity, but management of natural resources varies between islands due to island‐specific context with regards to socio‐political organization and strength of cultural heritage. Across the archipelago, bivalves harvested manually from the mudflats are an important part of the Bijagós people's diet, economy, and culture. Migratory shorebirds share the use of these mudflats during their non‐breeding season, consuming macrobenthos such as crustaceans and bivalves, including those harvested by local people. At the end of their stay in the Bijagós, just before taking off for their migratory flight, it is particularly important that shorebirds have access to undisturbed feeding areas with suitable food resources. In this study we start by exploring shellfishing patterns across different management regimes (via questionnaires to local shellfishers), then assess seasonal variation in the direct impact of shellfishing on shorebirds (through competition for resources and space), and finally quantify the indirect impact of sediment disturbance due to shellfishing upon shorebird prey availability with an experimental approach. Results indicate that bivalve resources are better managed in areas with formal protection, while traditional management based on cultural beliefs results in poorer stock conditions. Interestingly, the high density of shellfishers in mid‐winter (14.4 ind. km −2 ) decreased markedly towards shorebirds' fuelling period, when they benefit the most from reduced disturbance on the mudflats. Regardless of the season, no direct competition for resources was detected due to differences in targeted sizes. Indirect impacts caused by sediment disturbance during shellfishing were also mostly absent, causing only a small reduction on shorebirds prey density but with no effect on the available biomass.