Nightjar - a rare bird, a strictly protected species, which has its refuge in the forests of Łuków. The name refers to folk beliefs according to which nightjars flew to herds of goats and drank their milk. In Slavic beliefs, the nightjar was considered a bird that brings souls from Wyraj to be reincarnated, or as a zoomorphic representation of the souls themselves. The motif of nightjars in Slavic beliefs was used by, among others, writer Andrzej Sapkowski in his The Witcher saga. It also appeared in the works of Henryk Sienkiewicz ("Janko Muzykant").