Researchers have found that many internal defence mechanisms that are quiet in rural birds are much more active in those in cities. These biological pathways are pumping out extra antioxidants, immune system cells and detoxifiers – a sign that urban life is challenging their health.
Globally, bird numbers are dropping. According to figures published by conservation organisation BirdLife International last year, 40% of bird species have declining populations while 7% are increasing in number. BirdLife cites urbanisation as a force destructive to many bird species, but a few do well in cities, such as the adaptable great tit, whose population is on the rise. […]