Artificial Light Extends Birds' Active Hours

Recent research indicates that the presence of artificial light is prolonging the daily activity of birds.

Globally, numerous bird species are beginning their routines earlier due to the unusually bright conditions created by human-made lighting.

For many avian species, these extended light levels add nearly an hour to their days. Birds commence their morning calls around 20 minutes sooner and continue until approximately 30 minutes past their typical evening time.

This finding comes from a large-scale exploration of over 500 species of birds across various geographical locations, providing a detailed understanding of how human-generated lights are influencing the daily cycles of birds.

While it has been understood that light pollution can disorient birds, affecting navigation, this study reveals more about its impact, such as extending daytime activities.

Researchers like Gilbert, in collaboration with peers from Southern Illinois University, took an innovative approach by analyzing an extensive collection of birdsong recordings.

Collected largely through BirdWeather—a citizen science project employing devices that record bird calls—this data is part of an emerging global database, used to identify species and manage birdwatching information.

By cross-referencing birdsong data with satellite light pollution records and natural light periods, researchers quantified the extension of bird activity time.

It's uncertain whether increased activity has positive results, like improved feeding opportunities, or negative impacts, such as disrupting sleep or hormonal cycles.

Differential responses among bird species were noted. For example, American Robins and Northern Cardinals showed notable changes in behavior in brightly lit areas.

Some birds with larger eyes appeared more sensitive to light fluctuations compared to species with smaller eyes, like the Tufted Titmouse.

Birds roosting in enclosed spaces like tree cavities were less affected due to the shielding from surrounding lights.

According to Buler, an ecologist unaffiliated with the study, the research is groundbreaking in scope due to the incorporation of machine learning and public involvement in data collection.

This study signifies a shift in ornithological research, showing how expansive datasets can provide broader insights into avian behaviors in human-influenced environments.

The widespread influence of artificial light on bird activity, altering their natural behavior, suggests a global trend needing further study.