Is urban living bad for birds?
ARoughly one in five of the world’s bird species is found in cities, prompting research into the effects of urban living. Generalists, omnivorous in diet, tend to adapt to urban environments better than those with specialist requirements. But even within these species, there are indications that cities may not be good for birds’ health.
Researchers have found evidence that urban populations suffer from higher levels of oxidative stress compared to individuals elsewhere, which negatively impacts their health. Recently, attention has been focussed on ‘telomeres’ – the nucleoprotein structures found at the end of chromosomes. These promote genome stability, and there is evidence associating telomere length with lifespan and mortality rate.
If the pressures of urban living modify an individual’s oxidative balance, then this may result in shortened telomeres – something that has been found in urban great tits and blackbirds. But such health costs need to be set against all the possible benefits – for instance, the availability of food at garden feeding-stations.
Urban living has its benefits, but great tits ( right) may be at higher risk of dying young.