Possible causes for breading failure in common terns

Mogelijke oorzaken van slecht broedsucces in de visdiefkolonie bij terneuzen. Stand van zaken en aanbevelingen - 2003

Context of the study

Since 1997 the Dutch Coastal and Marine institute (RIKZ) monitors the coastal breading birds of the Delta area. One of these breading birds is the common tern. In 1994 the colony in Terneuzen was struck by serious signs of illness, while the other colonies in the delta area remained healthy. The number of breading couples decreased strongly, and the broedsucces vertaling!!!! was bad. In 1999 these signs of illness vanished and the number of breading couples increased again. However, from 2000 on the eggs started to show anomalies (small cracks or bulges), which indicated that the population still hadn't recovered.