Feathers turn grey: cross-sectional and longitudinal data from red-necked nightjars

This data set includes measurements of the prevalence of unpigmented (leucistic) feathers in red-necked nightjars (Caprimulgus ruficollis). Data on date of capture, sex, age, presence-absence of leucistic feathers and body size of each individual are also included in the data set. Fieldwork was carried out between 19 April 2016 and 15 October 2020 (5 years) in a protected area of the Doñana Natural Park (Spain). Nightjars were captured during the night (1-6 h after sunset) along a 24-km road transect using a butterfly net, measured for standard morphological traits and examined for the presence of leucistic feathers