Small, all black tern breeding colonially in well-vegetated fresh or brackish wetlands. Disjunct breeding range in W Europe, has declined greatly in W Europe due to habitat destruction and eutrophication (Beintema 1997). More common in E. Europe, range also includes W Asia and N America. Strongly migratory, travelling both at sea and over land. European birds winter Africa. Diet predominantly insects. Nest built in shallow water or floating on aquatic vegetation. Gathers in large flocks during post-breeding period. European population estimated at 74,400-154,000 breeding pairs, decreasing.