City living shortens great tits’ telomeres

Urban living could pose risks to great tits — at least in terms of their DNA. 

City life comes with a host of factors that can, for better or worse, affect a bird over the course of its life span. To see how urbanization might influence early development in great tits (Parus major), biologists at Lund University in Sweden took newly hatched great tits from the city and the country and mixed them up. They reared both urban and rural broods in urban and rural nest boxes. After just two weeks, great tits raised in urban environments had shorter telomeres regardless of where they were born, the Swedish team reports June 14 in Biology Letters.

Telomeres are bits of DNA that protect the ends of chromosomes from unraveling or degrading. The shorter telomeres get, the more likely cells are to die. Telomere length influences longevity in other birds as well as in humans. So if growing up in an urban setting shortens birds’ telomeres, it could lead to a host of other problems down the line, the team argues.