Urban environments have a profound effect on the internal
clocks of city residents both human and animal. These changes to biological
rhythms could lead to increased incidence of health problems and reduced
lifespan. Conversely, biological clocks could be modified to better function in
urban environment – questions that could be answered by studying wild animals.
Biologists from the University of Glasgow and the Max Planck Institute for
Ornithology in Germany have now discovered for the first time that the
biological rhythms of city-dwelling organisms are changing in response to city
living. The researchers measured the circadian rhythms of groups of urban and
rural blackbirds in southern Germany and found that the city-dwellers had
faster and less robust internal clocks than rural blackbirds. In the wild, city
birds woke up earlier and rested less than forest birds.