Light pollution hampers recolonization of revitalised European Nightjar habitats in the Valais (Swiss Alps)

Increasing light emissions caused by human activities have been recognized as a major threat for nocturnal animals. In Switzerland, the European Nightjar is a rare bird, decreasing in numbers since the 1970s, and is therefore highly threatened. The last breeding population occurs in the canton Valais. Initial expert-based conservation measures on formerly inhabited breeding sites were successful until 2000, however recent additional measures...