Auckland, Aug 6 (The Conversation): We've all experienced a restless night of sleep due to a snoring partner, a crying baby, or overly enthusiastic neighbors. Sleep disruptions are common and have unpleasant repercussions the following day, such as lack of motivation and difficulty communicating. However, this isn't a challenge unique to humans. A recent study discovers that birds too suffer when their sleep is interrupted, manifesting in the quality of their singing.
The Significance of Birdsong: Birds' vocalizations are incredibly diverse, stretching from simple calls like a chicken's cluck to complex imitations of various sounds, including human voices. These vocalizations play a critical role in communicating vital information about themselves and their environment. While calls are generally brief and straightforward, often signaling danger, food, or maintaining social bonds, songs are more intricate, utilized for mate attraction, territory defense, or claiming new territories.
Creating these sounds requires coordination across several body systems, including various parts of the brain, lungs, and throat muscles. Due to their complexity and precise timing, these vocalizations are prone to errors. In many bird species, frequent and complex singing enables better mate attraction and territory defense, making poor-quality songs a significant threat to reproduction and survival.
Sleep in Disturbed Environments: It's established that all studied animals need sleep, from jellyfish and worms to whales and birds. Many creatures, like bats, can sleep up to 20 hours a day. However, sleep quality has increasingly been compromised by urbanization. With ever-expanding cities, disturbances such as artificial light at night, noise pollution, and introduced predators are prevalent, even in once-remote areas, resulting in many birds living and sleeping in disrupted environments.
Research indicates that birds exposed to noise and light pollution experience less sleep, with frequent waking and reduced sleep intensity. As in humans, sleep is crucial for birds' brain development, memory, learning, motivation, stress management, cognition, and communication.
Effects of Sleep Deprivation on Birdsong: Our research focused on common mynas to examine how insufficient sleep affects their vocalizations. We compared the quantity and complexity of their songs and calls after a standard night's sleep versus a disturbed one. Just one night of poor sleep resulted in common mynas singing fewer and less complex songs, with increased daytime resting, indicating reduced motivation to sing and a preference for napping.
A similar study on Australian magpies observed comparable outcomes, with reduced singing and even diminished interest in favorite treats following sleep loss. Further experiments revealed that even half a night of sleep disturbance could affect common mynas' singing and activity, resulting in less singing and more resting.
Interestingly, birds disturbed in the first half of the night sang less than those disturbed in the latter half, though full-night disturbances had the most substantial impacts. Beyond singing, their calls also changed, becoming longer and lower in pitch. As these calls are essential for recognition and social communication, such changes could significantly affect interactions among these social birds.
The Implications for Birds: Our findings indicate that even brief sleep disruptions can negatively impact birds’ vocalizations. Yet, in nature, sleep disturbance is rarely an isolated event. Chronic light and noise pollution likely compromise the quality of birds' songs and calls continuously, raising concerns about urbanization's impact on bird communication, reproduction, and survival.
While common mynas are an invasive species that have adapted well to urban environments, native species might struggle with sleep disruptions caused by urbanization. Cities can take measures to mitigate night disturbances and enhance birds' sleep quality, such as increasing safe, quiet roosting areas like trees and parks. Reducing unnecessary lighting, employing dimmers, and using downward-facing, warm lights, along with imposing restrictions on heavy or modified vehicles and fireworks, can help lower night noise pollution to protect the natural sleep patterns of wildlife in urban areas. (The Conversation) RD
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