The familiar chorus of birdsong is a defining feature of the morning, yet many people are surprised to hear chirps, whistles, and melodies after sunset. While most avian species are diurnal, certain circumstances and specific species make the nighttime a vocal period. Identifying the source depends on where you live and the characteristics of the vocalization itself. The performers range from genuinely nocturnal hunters to common daytime songbirds whose internal clocks have been reset by the modern environment. Determining which bird is singing, and why, can help decode the soundscape of the dark hours.
True Nocturnal Vocalists
Some birds are naturally adapted to the night, making their vocalizations a regular part of their biology. These true nocturnal species often belong to the family of birds known as nightjars, which includes the Eastern Whip-poor-will and the Common Nighthawk. The Whip-poor-will is famous for its loud, repetitive, onomatopoeic call that can continue for many minutes. It is often heard in eastern woodlands and rural areas.
The Common Nighthawk is a crepuscular bird, active at dawn and dusk, which produces a buzzy, distinctive call while hunting flying insects high above. A relative, the Common Poorwill, is the only bird known to enter torpor. It makes a soft call that sounds like its name, typically found in arid landscapes and rocky hillsides in the western United States. These birds are masters of camouflage and are rarely seen, but their unique calls are unmistakable.
Diurnal Birds Singing After Dark
The nighttime singing of diurnal birds is primarily a response to environmental pressures in human-dominated landscapes. One significant factor is artificial light pollution, which disrupts the avian circadian rhythm that regulates daily activities. Birds rely on the natural light-dark cycle to cue when to wake, forage, and sing. Streetlights and other sources of light can trick them into thinking dawn has arrived early.
This confusion can extend a bird’s active hours, causing them to begin their morning song earlier or continue their evening song later. Another explanation is the masking effect of daytime noise in urban areas, such as traffic and construction. Birds use song to defend territory and attract mates. Their vocalizations are more effectively heard when ambient noise levels drop significantly at night, ensuring their messages are not drowned out by the daily human din.
Identifying Common Urban Night Chirpers
The most frequent source of singing in urban and suburban environments is the Northern Mockingbird, a species notorious for its nocturnal repertoire. Mockingbirds are not true nocturnal species, but unpaired males sing throughout the night during the spring and early summer breeding season to attract a mate. The key to identifying a Mockingbird is its remarkable ability to mimic, often stringing together sequences of up to 200 different songs, imitating other birds, frogs, and sometimes even mechanical sounds.
The American Robin is another common source of night singing, particularly in areas with significant light pollution. Unlike the Mockingbird’s varied and complex song, the Robin’s nocturnal performance tends to be a more cheerful, caroling series of whistles and notes, usually heard just before dawn or late in the evening. The male’s song is a consistent pattern of high-pitched phrases. This contrasts with the Mockingbird’s habit of repeating a phrase a few times before quickly switching to a completely new sound.
Beyond the Birdsong
When investigating a persistent nighttime chirp, it is important to first rule out non-avian sources, which are often the true origin of the noise. Insects are the most common misidentification, particularly crickets and katydids, which use sound to attract mates and are active at night. These insects generate their calls through stridulation, rubbing their wings together to produce a high-pitched, continuous, and mechanical chirp.
The continuous, repetitive nature of insect sound differentiates it from the more intermittent, varied song phrases of most birds. Tree frogs and toads also produce chirping and trilling noises, especially near water sources, and their calls can easily be mistaken for a bird. If the sound is highly mechanical, unvarying in pitch, and seems to be coming from a low, grassy area, the source is likely an insect or an amphibian.