Urbanization, which involves land development, is an increasing problem for wild animals the world over. Stressors such as pollution, noise, artificial light and the lower-quality food found in cities are considered unhealthy for animals. Studies of urbanization in birds, including my research, are usually designed to elucidate its detrimental effects, with some interesting exceptions. Together with Hannah Watson, a colleague at Lund University in Sweden, I measured levels of corticosterone, or CORT, a common stress hormone in birds, in 188 urban and rural Great Tits. Contrary to expectations, the urban birds had consistently lower levels of CORT than forest birds. This finding is even more remarkable when you consider that urban populations are denser than forest ones, which should increase competition for territories and food and hence ramp up stress.