Habitat use and foraging ecology of the nightjar (Caprimulgus europaeus) in the Swiss Alps:: towards a conservation scheme

The European nightjar is one of the most endangered bird species in Switzerland. As its ecology in the country is poorly understood, we collected data on resource exploitation in the upper Rhone valley (Alps). The diet of two adult birds and one nestling consisted primarily of moths (81 and 93% of biomass), which were also the most abundant prey sampled at the study site. Three radiotracked nightjars selectively exploited oak scrubland compared to vineyards and pine forests, vineyard monocultures harbour presumably insufficient moth populations, whereas dense pine stands probably do not provide the flying and foraging requirements of nightjars. The survival of nightjars in Valais probably depends both on the existence of sufficient populations of moths and on the availability of semi-open natural habitats, such as oak scrubland, which seem to offer the best suitable foraging and nesting places. (C) 2001 Elsevier Science Ltd. All rights reserved.