Tiny trackers reveal where migratory shorebirds need protection across Africa

Researchers in South Africa have fitted 23 small wading birds with sub-2-gram satellite transmitters in a first-of-its-kind study to map the migration routes of two vulnerable shorebird species. The project, led by BirdLife South Africa in collaboration with Wetlands International and the Max Planck Institute for Biological Intelligence, tracked curlew sandpipers and grey plovers from their South African wintering grounds to Arctic breeding sites.

Both species were reassessed as Vulnerable to extinction by the IUCN in 2024, reflecting rapid population declines. The satellite tags, solar-powered and weighing less than two grams, transmitted location data as the birds flew north. Six birds reached Arctic breeding grounds, six remained in Africa (likely first-year birds not yet migrating), and eight stopped transmitting, possibly due to device failure or predation.

The tracking revealed three main migration routes from South Africa's Western Cape: through central Africa, east via the Free State, or west along Namibia's coast then east across southern and central Africa. Key stopover sites identified include the Makgadikgadi Salt Pans in Botswana, the Sudd wetland in South Sudan, the Mesopotamian marshes in Iraq, and Lochinvar National Park in Zambia. Several of these critical habitats have no formal protection status.

The findings have direct conservation implications. The Luapula floodplain in Zambia, a dense papyrus swamp used by migrating birds, currently has no protected status. BirdWatch Zambia is now prioritizing field visits to update information on 42 Important Bird Areas, some of which have been lost to development. BirdLife South Africa is also working with landowners to rehabilitate salt marshes at the Berg River estuary, where accelerated erosion and habitat degradation threaten the birds' primary feeding grounds.

For the earth observation community, the study demonstrates how miniaturised satellite tracking technology is expanding the frontier of conservation biology. Tags small enough to fit on a bird weighing as little as 50 grams can now reveal migration pathways that were previously invisible, enabling targeted protection of critical stopover habitats across international boundaries.