Since the end of the 19th century suitable habitat of Nightjars decreased and fragmented very fast. Because of this Nightjars were added to Annex I of the Birds Directive. On the Flemish Red list Nightjars were added to the list of 'vulnerable species' who can change to a 'endangered' status. By exception of some Walonian small populations in Lagland, Spa-Malchamps an Croix-Scaille (50-60 pairs) most Nightjars of Belgium occur on the sandy soils of the Campine area.

After an absolute minimum of only 208-281 pairs in 1980 the population in Flanders seems to be increasing, but population estimates diverge extremely. In the province of Limburg the population is estimated on 500 pairs in 2002 an 800 in 2008. It is really important to interpret these numbers with great cautiousness because these estimates are made based on the number of male churring locations. However, by radiotagging male Nightjars we have discovered that males sometimes have 3 to 5 churring locations in one season. This means the number of pairs presumably is lower than current estimates.