The crested Tern Thalasseus bergii breeds in the tropical and temperate coastal zones of Namibia, South Africa, on the islands of the Indian Ocean up to Australia and the western Pacific Ocean. In the western Indian Ocean, the population is estimated at approximately 14000 breeding pairs (Le Corre and Bemanaja on 2009). In Madagascar, as in other parts of its distribution, the species forages in shallow water, and breeds in dense colonies on coastal islands. After breeding, the species disperses and rests on sandbanks, seashores and islets as well as estuaries and mangrove swamps (Langrand on 1990, Safford and Hawkins on 2013). From 18 to 25 June 2012, we conducted a field expedition in the Marine Protected Area of Ambodivahibe (North East Madagascar), which encompasses a large coastal zone and eight nearshore islets. Overall, we observed 8113 coastal and marine birds belonging to 28 species and 10 families.

The most interesting finding was a large concentration of crested terns (6072 individuals), including a large breeding colony of 2836 nests on the islet of Bataiza (location: 12°22 ‘ 2.83″, 49°31 ‘ 49.39″ E). This small islet (1,54 ha) is located at 800 m of the coast of Ambodivahibe. Most nests were occupied by incubating adults and others had chicks of various ages. We also found 10 dead birds (mostly chicks, but also 3 adults), possibly killed by black rats, which are abundant on the islet. This breeding colony is the second in size in Madagascar, after the colony of Nosy Foty located in the archipelago of Nosy Hara (10840 breeding pairs) in the northwest of Madagascar (Le Corre and Bemanaja, 2009). The inclusion of these coastal islets in the Marine Protected Area of Ambodivahibe reduced poaching and was probably very beneficial for the species.

We thank WWF , Conservation International Madagascar and Asity Madagascar for their collaboration. Our sincere thanks to all the team in particular Mr Jaomazandry and Saïd and the local associations based in the site of Ambodivahibe for their friendly collaboration.