It is common for birds to vocalize at night, especially during the spring and summer months. While less singing is heard at night compared to daytime, nocturnal bird vocalizations are a normal part of avian behavior. There are several reasons why birds call at night.
Defending Territory
Many birds sing at night to establish and defend their territories. Birds define boundaries with sound, and nocturnal song reminds other birds of a territory holder’s presence. Owl calls are one example of territorial vocalizing at night. Resident owl species like barred owls and great horned owls hoot to claim their hunting territories and chase away intruders.
Attracting Mates
Nocturnal singing is also a strategy used by male nightjars, an avian family including nighthawks, whip-poor-wills, and common poorwills. The males perform display flights and sing continuously to attract a mate. The chorus of nightjars calling at dusk and during the night is linked to breeding activities.
Moonlight Singing
Birds like thrushes and skylarks are known to break into song on moonlit nights. Moonlight triggers hormonal changes in birds that prompt this unusual night singing behavior associated with breeding. The moonlight singing by European robins coincided with hormonal changes triggered by exposure to nocturnal light.
Dawn Chorus
Many diurnal songbirds participate in a dawn chorus, which is a period of high vocal activity taking place in the early morning hours before sunrise. Birds preparing to become active for the day may instinctively sing when first awaking during the dawn twilight period.
Bird Species that Call at Night
While most birds are diurnal, or active during the daytime, there are over 100 species of nocturnal birds worldwide that are active at night. Some examples of birds that vocalize at night include:
Owls
Owls are highly vocal nocturnal predators. Most owls hoot to communicate with other owls and defend territories. Some owl calls also help confuse prey. Great horned owls, barred owls, barn owls, and screech owls are just a few owl species known for nocturnal hooting.
Nightjars
Nightjars are a family of nocturnal birds including nighthawks, whip-poor-wills, and common poorwills. Male nightjars sing continuously to attract mates, with peak calling occurring during the breeding season.
Rails
Some rail species, like clapper rails and king rails, are known to call at night. Males vocalize to attract females and defend territory. These wetland birds prefer to call at night when their marshy habitats are quieter.
Seabirds
Seabirds like shearwaters, storm petrels, and some gulls may return to breeding colonies or roost sites after foraging at sea and vocalize at night. Their calls serve to communicate with other birds and relocate mates and nests in the dark.
Songbirds
While most songbirds sing during the day, some like European robins may belt out songs on moonlit nights. Thrush species also engage in nighttime vocalizations. Even some daytime songbirds will participate in dawn choruses before sunrise.
Shorebirds
Some shorebirds are known to call overnight, like killdeer. Their haunting nocturnal kill-deer calls are thought to communicate over long distances and establish territories. Other shorebirds may roost communally at night and vocalize.
Swifts
Swifts like common swifts frequently engage in a behavior called crepuscular calling where they vocalize intensely at dusk after returning to their nesting sites. This helps the swifts locate their own nests and mates in poor light conditions.
Why Don’t Birds Sing at Night?
While some bird species exhibit nocturnal vocal activity, most birds do not sing at night for several reasons:
Resting
Singing expends energy, so most birds conserve energy at night by resting and remaining quiet. With reduced activity at night, birds don’t have to communicate with other birds as loudly as they do while active during daylight.
Lowered Defenses
Singing could attract the attention of nocturnal predators, putting resting birds at greater risk overnight. Keeping quiet helps keep hidden sleeping birds safer.
Less Territory Defense
Birds sing during the day to defend territories from rival birds. With reduced competition and territorial threats at night, most birds don’t need to vocally guard resources while roosting.
Impaired Hearing
Many birds may have reduced hearing sensitivity in low light, so singing messages are less effective at night. Most communication occurs when hearing is optimal during daytime activities.
Circadian Rhythms
Singing behavior corresponds to daily cycles of light and dark. Hormones control singing activity on a circadian rhythm, with peaks occurring during daylight hours rather than at night.
Less Need to Communicate
With limited activity occurring nocturnally, diurnal birds have less need to communicate important messages like territory alerts, mating availability, flock coordination and alarm calls at night.
Nocturnal Bird Adaptations for Singing in the Dark
Birds that vocalize at night have special auditory and vocal adaptations for seeing well and communicating in the darkness. These include:
Enhanced Hearing
Owls and other nocturnal bird species have asymmetrical ear placement and enlarged ear openings to maximize sound reception in low light. This improved directional hearing helps birds pinpoint calls in the dark.
Sound Localization
The facial ruffs around some owl species’ faces help localize sounds and detect prey in darkness. Their concave facial discs also funnel sound to their ears for improved night hearing.
Excellent Night Vision
Increased rod density in the retinas of nocturnal birds enhances visual sensitivity for better night vision. Owls have massive eyes to take in more light at night.
Loud, Clear Calls
Nocturnal birds often have loud, far-reaching vocalizations that are easier to hear at night over long distances.calls. Certain owl hoots and nightjar songs carry for over a mile.
Lower-Frequency Calls
Birds singing at lower frequencies that don’t degrade as easily are better adapted for transmitting noises at night. The barred owl’s distinctive eight-note hooting call resonates well in darkness.
Synchronized Duets
Some nocturnal species coordinate synchronized duets, with mates alternating calls. This helps the pair stay in contact on shared territories in darkness.
Conclusion
While most birds sleep and remain quiet at night, nocturnal vocalizations are normal and natural behaviors for certain avian species. Birds rely on specialized auditory and visual systems to effectively communicate important territorial, breeding and social signals in darkness. Nocturnal bird songs demonstrate the incredible adaptation of biological rhythms to optimize critical activities both by day and night.
Bird Family | Example Species | Nocturnal Behaviors |
---|---|---|
Owls | Barred Owl, Great Horned Owl | Hooting, territory defense |
Nightjars | Whip-poor-will, Common Nighthawk | Continuous song displays to attract mates |
Rails | King Rail, Clapper Rail | Territorial calling, pair duetting |
Seabirds | Shearwaters, Storm Petrels | Colony calls, mating calls |
Songbirds | Thrushes, European Robin | Dawn and moonlight choruses |