Light Pollution May Impact Love Lives of Blue Tits

Light pollution is becoming more widespread as cities branch out and people chase away the darkness with electric lighting. Now, scientists have taken a closer look at how this type of light pollution impacts a species of birds called blue tits.

Circadian rhythm, or the internal "body clock" of a species, influences the behavior of living beings. Light is especially important for regulating circadian rhythm in birds.

In order to get a better sense of how light pollution impacts bird behavior, the researchers used LED lights to illuminate various areas of the Viennese Forests for two additional hours in the morning, before sunrise, and in the evening after sunset. During this period, the researchers examined activity patterns that included singing and mating behavior, growth and development of nestlings, and stress hormones.

"We assume that light at night affects the birds' strategies of choosing partners," said Katharina Mahr, one of the researchers, in a news release. "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. Besides, male blue tits are 'morning singers.' Particularly fit males start to sing pre-dawn songs. We also know that female blue tits tend to be unfaithful to their partners, but do so covertly. Therefore, we want to find out whether artificial light generates a certain conflict between the sexes."

The researchers found that light pollution does indeed impact blue tits. As light pollution continues, it's important to dispense with unnecessary sources of light. For example, illuminated billboards could be dispensed with, and non-illuminated zones could be planned.

The findings are published in the journal Frontiers in Zoology.