A nocturnal bird refers to a bird species that is active during the night and sleeps during the day. Some synonyms for the term include night bird, nocturne, noctivagant, and nightjar. Night bird is a common synonym, particularly used to describe owl species. Nocturne is a more poetic term that emphasizes the bird's activity at night. Noctivagant refers to a bird that is active or travels at night. Nightjar is a term that describes members of the family Caprimulgidae, which includes several species of nocturnal birds. All of these terms accurately describe the behavior of nocturnal birds and can be used interchangeably to refer to them.