From 1964 to 1988 the Nightjar decreased with 85% in an area of 800 km². The last 50 territories are one of the strongholds of the Netherlands. Changes in habitat, caused by dynamics in vegetation, recreation activities and athmospheric deposition are the main reason. New habitats are seldom occupied anymore. Irregular foodsupply and late springarrival, as a result of a colder climate, can lead to insufficient reproduction. There is small evidence for this conclusion.