Although most bird species are active and vocal during the day, a select few sing or make loud, repetitive calls after sunset. These nighttime vocalizations come from birds that are genuinely nocturnal, with their activity cycles naturally beginning after dusk. The calls are typically complex, melodic songs or simple, persistent repetitions, serving a clear biological purpose. Understanding which species are responsible and why they break the traditional daytime pattern reveals insights into avian behavior and the impact of the human environment.
Identifying the Primary Nocturnal Singers
A small number of species are truly nocturnal vocalizers, meaning their primary time for communication is after dark. The European Nightingale is perhaps the most famous, known for a powerful and melodic song that fills the air when most other birds are silent. Only unpaired males typically sing throughout the night, using their extensive repertoire of up to 250 different song types to advertise their presence and attract a mate. The song is characterized by clear whistles, trills, and gurgles, which are particularly noticeable in the quiet of the night.
Across North America, the Eastern Whip-poor-will is another prominent nocturnal voice. Its vocalization is not a true song but a continuous, loud chant. This species, a member of the nightjar family, repeats its own name—”whip-poor-will”—hundreds of times during the summer nights. As an aerial insectivore, its nocturnal calling aligns with its primary foraging period, helping to defend its breeding territory and attract a partner. The Whip-poor-will often times its egg-laying so that chicks hatch around ten days before a full moon, allowing parents maximum light for all-night foraging to feed their young.
Diurnal Birds Singing Under Artificial Light
Many reports of nighttime singing involve species that are diurnal, extending their singing hours due to environmental factors. Two commonly cited examples in North America are the American Robin and the Northern Mockingbird. These birds are often heard vocalizing late into the evening or beginning before dawn, sometimes continuing throughout the darkest hours.
The primary environmental trigger for this extended activity is artificial light pollution from sources like streetlights and business signs. Such illumination interferes with the bird’s internal clock, or circadian rhythm, effectively tricking it into perceiving that the day is longer. This causes the bird to begin its dawn chorus earlier or prolong its evening singing.
Noise pollution during the day can also drive birds to sing at night. Studies suggest that in urban environments, diurnal species like the European Robin sing nocturnally because the relative quiet allows their songs to propagate more clearly. By avoiding the high volume of traffic and human activity during the day, the birds ensure their territorial and mating messages are received.
The Biological Drive Behind Nocturnal Calls
Whether a bird is naturally nocturnal or is singing due to an environmental trigger, the biological reasons for the vocalization remain consistent. Singing is energetically expensive, so the benefits of communicating must outweigh the costs of calling in the dark. The two primary functions are mate attraction and the defense of a breeding territory against rivals.
For unpaired males, singing at night can be a final effort to attract a mate after the competition of the day has subsided. By vocalizing when most other species are quiet, a bird claims a unique acoustic space, ensuring its song is not masked by the daytime chorus. This allows their message to be heard with minimal interference, a significant advantage during the breeding season.
For naturally nocturnal species, their singing time is simply aligned with their active period, when rivals and potential mates are also active. This is relevant for insectivores, where the timing of their foraging activity dictates when they must be awake and communicating. The nocturnal environment is not a barrier to communication but the optimal time for it.