'Light Pollution' Affects Love Lives of Viennese Birds

"Light pollution" from artificial light in cities may affect the love lives of birds in the Viennese Forest, according to recent research.

Artificial light has negative affects on humans and the environment, but it reportedly impacts the reproductive behavior of blue tits. Researchers are hopeful that their study could help develop concepts, minimizing negative effects on the lives of animals and the ecological system, by reducing light sources in specific regions.

The circadian rhythm or "body clock" influences the behavior of living beings, and for these birds they rely on light to know when it is time to mate, breed, forage or migrate. If the natural day and night rhythms are affected by artificial light, the natural behavioral patterns of the animals may also change.

"There are studies investigating the effect of artificial light on the orientation and activity of birds. Light, for instance, limits the sense of orientation, but also activity patterns in birds to a great extent," co-author Katharina Mahr said in a statement.

The Viennese research team tested the effects of artificial light by shining LED lights on parts of the Viennese Forests for a period of three weeks. They focused specifically on blue tits because they already know a lot about their reproductive and mating behavior, and could more easily detect changes in mating.

After experiencing two additional hours of light before sunrise and after sunset, the researchers found that female blue tits "get it on" with more male partners, showing that circadian rhythm influences mate choice.

"We assume that light at night affects the birds' strategies of choosing partners. Males, for instance, like to be in the 'limelight' whereas females might prefer to 'remain in the dark.' Thus, light may exert different effects on the love lives of the different sexes," Mahr explained.

Researchers speculate that more light at night means that the birds are restless and therefore more prone to occupying their time with other "activities."

"Urban lights are obviously important for human safety and comfort. Nevertheless, urban planning should take into account the question of where light sources are really necessary," Mahr added.

The study's findings were published in the journal Frontiers in Zoology.