Most birds are diurnal, resting at night. However, some species feed after dark, driven by ecological pressures and adaptations for low-light environments.
Birds That Feed at Night
Birds that forage after dark are broadly categorized into truly nocturnal, crepuscular, and opportunistic feeders. Truly nocturnal birds, like many owls, are active and hunt throughout the night. Examples include the Great Horned Owl and Barn Owl, specialized predators of small mammals.
Crepuscular birds are most active during twilight hours, at dawn and dusk, when light levels are low. Common Nighthawks and European Nightjars hunt insects during these transitional periods. Some typically diurnal birds may feed at night under specific circumstances, such as during migration, severe weather, or when food is scarce, supplementing their daytime foraging.
Why Birds Feed After Dark
Feeding after dark offers several advantages. One benefit is reduced competition for food resources from numerous diurnal species, allowing nocturnal and crepuscular birds access to food sources.
Certain prey, like moths, nocturnal insects, and small mammals, are primarily active at night, making them available for specialized nocturnal hunters. Foraging under darkness also offers increased safety by reducing predation risk from diurnal predators. In hot climates, nighttime foraging helps conserve energy and manage body temperature.
How Birds Find Food in the Dark
Birds adapted to low-light conditions possess unique sensory and physiological features for effective navigation and foraging. Many nocturnal birds, such as owls, have exceptionally large eyes, up to 75% of their skull space, maximizing light intake. Their retinas are rich in rod cells, highly sensitive to low light and motion, though this often means less color perception. Owls also have tubular eyes fixed in their sockets, rotating their heads up to 270 degrees to scan surroundings.
Beyond vision, acute hearing is a primary adaptation for many nocturnal predators. Owls possess facial discs that funnel sound to their ears, and some species have asymmetrically placed ear openings, pinpointing prey location by sound. This auditory precision, combined with specialized feathers for near-silent flight, allows owls to approach prey undetected.
Some birds, like nightjars, use tactile senses through bristles to detect insects. Kiwis primarily rely on smell. Rare echolocation exists in birds like the Oilbird and certain swiftlets, which produce clicks to navigate dark caves.
Factors Influencing Night Feeding
External environmental factors significantly influence night feeding, especially for non-nocturnal species. Artificial light, like streetlights, attracts insects, drawing in birds that might not typically forage after dark. This light pollution can alter natural rhythms, encouraging some species to extend their activity into the night.
During food scarcity, harsh winters, or droughts, diurnal birds may extend foraging into twilight or dark hours out of necessity. Migration is another factor, as many birds travel at night to avoid predators, take advantage of cooler air, and conserve energy. They may opportunistically feed during brief nocturnal stops to refuel. Moonlight also plays a role, influencing prey visibility and activity levels of nocturnal birds and their food sources.