Study finds city life is tough on young birds

Sept. 8 (UPI) -- Scientists from Lund University found in a recent study that city life can be difficult for young birds, but if they survive their first year, they are less susceptible to stress.

"It seems that the various stress factors in the city do not affect the survival of adult individuals in the same way as they affect that of young birds," Pablo Salmón, a research student in biology at Lund University, said in a press release.

The study, published Wednesday in the Proceedings of the Royal Society B, examined the young and adult great tits in Malmo, Sweden, and compared their survival rates with the same species in rural areas.

Scientists found that great tits in city environments have a harder time reaching maturity, but if the birds do survive their first year the negative effects decrease.

The study identified telomeres, the extremity of the chromosome, as the mechanism that predicts the difference in birds' survival between rural and urban environments.

Telomeres are found in humans as well as other animals and work to protect the chromosomes and the genome. The longer the telomeres, the better the chance for a longer survival of a species.

"Our study is the first to show the connection between telomere length and the survival of individuals in the urban environment," Salmón said.

Scientists found that only young birds with long telomeres survived their first year in a city environment. The correlation between telomere length and survival was found in birds in rural environments, however, the effect was significantly stronger in urban birds.

The study was not able to determine exactly what in the urban setting made birds with shorter telomeres die sooner.