Roseate Terns Sterna dougallii successfully rearing a young Sandwich Tern S. sandvicensis

Abstract

Isle aux Dames in the Bay of Morlaix, northern Brittany (48°41’N 3°53’W), holds one of the largest mixed tern colonies in France, with Sandwich Terns Sterna sandvicensis, Roseate Terns S. dougallii and Common Terns S. hirundo, and this island has been the main French Roseate Tern colony since the 1980s (Cadiou et al. 2004; Le Nevé 2005). Annual surveys are conducted to obtain data on breeding numbers and productivity. In 2007 the census of the colony was carried out on 12 June by a team of eight experienced and inexperienced people. Different teams covered different areas of the colony, counting nests, using different colour of small paper marks put inside to avoid double-counting, and reporting nest-contents.