A Global Study Reveals How Light Pollution Impacts Birdsong and Wildlife Behavior

Have you ever been kept awake by a bird singing outside your window when it should be dark? A recent study suggests that bright city lights may be the cause. Researchers examined data from over four million birdcalls worldwide and found a correlation between artificial lighting at night and the duration of birdsong.

The study's co-author, Brent Pease, highlighted light pollution as a growing concern for both human and wildlife health. He noted that while the effects of light pollution on human health are well-studied, its impact on wildlife is still an evolving area of research. Light pollution is increasing, with some estimates indicating a 10% annual increase in brightness in populated areas.

The research utilized data from the BirdWeather project, a network of sound recorders deployed by volunteer citizen scientists globally. The recorded audio was analyzed using an algorithm to identify bird species. The study analyzed millions of morning and evening calls from hundreds of different bird species, collected between March 2023 and March 2024.

The findings revealed that areas with higher levels of light pollution also exhibited increased birdsong activity in both the morning and evening. On average, birds in the brightest areas sang for an additional 50 minutes per day. The impact of light pollution varied significantly among different bird species.

The Australian magpie-lark was found to be particularly affected by light pollution. These birds, found across mainland Australia, began their morning calls nearly 40 minutes earlier in bright areas. The study's co-author, Neil Gilbert, noted seasonal and spatial variations in the effect on magpie-larks.

Birdsong is often linked to attracting mates, and the researchers found that light pollution's effects were most pronounced during breeding seasons. A behavioral ecologist not involved in the research praised the study's comprehensive dataset, emphasizing the importance of understanding these patterns for conservation efforts. However, the researchers acknowledged that the citizen science dataset overrepresented certain regions.

There is growing evidence that artificial light disrupts wildlife behavior and health. Light pollution is particularly problematic for migratory birds, many of which fly at night. While the researchers don't yet have definitive evidence that extended singing is detrimental to all bird species, they acknowledge the potential negative impacts on health due to reduced resting time. They also recognize the potential for increased foraging and breeding opportunities. They emphasize the need for further research and efforts to reduce light pollution.