City Life Affects Birds Similarly to People, Study Says

In the world's bustling cities, where taxi cabs full of passengers zoom down neon-lit streets at all hours of the night, the effect of such a lifestyle on a person's internal clock is noticeable. City people live life at a faster pace compared with those in more rural settings. And it turns out the same is true of city birds when compared to their forest-dwelling kin, according to new research.

Biologists from the Max Planck Institute for Ornithology and the University of Glasgow have determined that the biological rhythms of city-dwelling birds are changing in response to city living.

For their experiment, researchers tagged adult male European blackbirds living in Munich, Germany and a forest outside of the capital city with tiny radio transmitters. After monitoring the birds for three weeks, the data revealed that while the forest birds began their activity at dawn, the city birds were active nearly half an hour earlier, on average, and in the evenings the city birds remained active for six minutes longer than their forest-dwelling cousins.

The tagged birds' circadian rhythms were also measured in a controlled environment, where no environmental information, such as dawn and dusk, could serve as a "clock." In this setting, the urban birds' behavior became more erratic than the forest birds

"We found that the rhythms of urban birds in the wild differ significantly from their forest counterparts," Barbara Helm, of the University of Glasgow's Institute of Biodiversity Animal Health and Comparative Medicine, said in a statement.

"In constant laboratory conditions, urban birds' circadian rhythms were clearly altered, running faster by 50 minutes than forest birds and being clearly less robust. There seems to be a different beat to city life."

The findings helps explain earlier research that reports urban songbirds adopt more nocturnal lifestyles, as reported by Nature.  

Davide Dominoni, lead researcher and ecologist at the Max Planck Institute for Ornithology, said such weakly-set biological clocks could be beneficial to urban blackbirds. "It could make them better at coping with city environments that are not as predictable as the wilderness," he said, according to Nature. But the condition may also cause adverse health effects, such as sleep deprivation, that may shorten the birds' lives.  

Researchers said the study is the first to confirm that when sharing human habitats, a wild animal species has a different internal clock.

Previous research on humans has suggested disrupted sleep patterns are linked with increased incidences of depression, obesity and some types of cancers, the Max Planck statement said.

"We'd be keen to find out the costs and benefits of modifying biological rhythms in blackbirds and other animals commonly found in our cities. This may help us to better understand the challenges of coping with urban life."

Dominoni and his colleagues' research is published in the journal Proceedings of the Royal Society B.