Urban environments disrupt not only human rest but also the sleep of birds, with measurable effects on their vocal behaviour, according to a new study.
Bird vocalisations range from simple calls for signalling danger or food to complex songs used in courtship and territory defence. Birds that sing more often and with greater complexity tend to attract better mates and secure territories, so poor song quality can affect reproduction and survival.
Sleep is vital for all animals, supporting brain development, memory, learning, motivation and communication. Yet urbanisation exposes birds to chronic light and noise pollution, reducing sleep quality.
The study examined Common Mynas, comparing their songs and calls after undisturbed and disturbed nights (Neil Loverock).
Experiments with Common Mynas
In a new study published in Proceedings of the Royal Society B: Biological Sciences, researchers studied Common Mynas, comparing their vocalisations after undisturbed and disturbed nights.
Merely one disrupted night led to fewer and less complex songs, with birds resting more during the day. Calls also became longer and lower-pitched, potentially altering social communication.
Even half a night’s disturbance reduced singing, and disruption in the first half of the night had a greater effect than in the second. A similar earlier study with Australian Magpies found that sleep-deprived birds not only sang less but also showed reduced interest in food.
Implications for urban wildlife
Given that noise and light pollution are constant in cities, birds may face ongoing declines in song quality, with possible impacts on communication, reproduction and survival. While Common Myna has proven to be an adaptable species, native birds may be more vulnerable.
The researchers recommend measures to reduce night-time disturbances, including more quiet roosting spaces, dimmed or shielded lighting, and lower nocturnal noise from vehicles and fireworks.
Reference
Mussoi, J G, et al. 2025. The effects of sleep disturbance on a songbird’s vocal performance. Proceedings of the Royal Society B: Biological Sciences. DOI: 10.1098/rspb.2025.1409