When can caprimulgiform birds be active at night?

Caprimulgiform birds are primarily crepuscular, meaning their activity is largely concentrated during dawn and dusk. However, they can be active at night under the following conditions:1

• Sufficient Illumination: They are nocturnal when there is enough light, particularly when aided by moonlight.1
• Specialized Adaptation: The oilbird is uniquely equipped for nocturnal life because it utilizes a system of echolocation. This allows the species to fly freely and forage in total darkness, leaving their cave roosts at dusk and returning at dawn.1

Additionally, while these birds are generally known as twilight- or night-flying creatures, some species may become active on dark, cloudy days, and a few are considered somewhat diurnal.12