Sterna hirundo

Common terns can be found in large parts of the world, particularly in France, where they nest most often on sand or galateous banks, both in coastal areas and inland, always close to the water. The largest coastal colonies in France are found along the coast from Charente-Maritime to Côtes d’Armor. Highly migratory, the species leaves its breeding grounds in mid-August and September to winter as far south as West and South Africa. Breeding terns from northern Europe also migrate through France, especially along the coast, creating large gatherings of birds on the coast at this time.

Common terns fish during the day and their foraging radius during breeding is restricted to 15-20km from the colony. No telemetry data exist to define the foraging areas of breeding terns on French colonies.

Adult Sandwich and Common Terns are captured during incubation on their nests at the edge of colonies.

Common terns, which are smaller than caugek terns, are equipped with Pathtrack GPS tags weighing around 3.2g, attached to a silicone harness fitted like a small backpack around their wings. This system is designed to fall out after just a few weeks, the time it takes to reproduce, as these ultra-light GPS units do not transmit their data live via the GSM network. Data are collected by a UHF antenna installed on the outskirts of the colony. When the terns leave on migration, the beacons can no longer transmit their data and become useless. In 2024, common terns will be fitted with new 3g 3G GPS units and fixed more permanently to obtain information on their migratory movements.

This is the first time such a study has been carried out on common terns in France. The target colonies are in Vendée (Réserve Naturelle Régionale du Polder de Sébastopol à Noirmoutier), Brittany (Réserve Naturelle Nationale des Glénans) and on the Channel coast.

Migratory in France

Breeder in France

: Wintering in France