The Black tern (Chlidonias niger) is in my opinion one of the most graceful birds I have seen. In the Millingerwaard Black terns gather every year to breed. They used to breed on floating water plants and especially Water soldier (Stratiotes aloides). Due to water and water soil pollution Water soldiers went scares and the Black terns now often breed on little rafts as they do in the Millingerwaard.
The colony is full of activity the morning I visited them. Food is brought to the breeding partners on the rafts constantly. As soon as a potential tread is spotted all the Black terns fly up to protect their nests. Altogether a beautiful thing to observe.