Urban areas are the most rapidly expanding form of land cover across the globe and more than half of the world’s population live in urban centres. This has significant implications for standards of living, human health and the environment. Just as the development of urban areas presents both opportunities and challenges for people, urbanisation offers advantages and disadvantages for wildlife. Some animals actively avoid towns and cities, while others manage to co-exist alongside humans. Birds are a typical feature of urban wildlife. Towns and cities can potentially benefit birds by offering a milder climate and an abundance of food. However, just as there can be adverse effects for human health, there may also be negative effects for birds, associated with exposure to air pollutants, artificial light and noise in urban areas.
There is increasing evidence that exposure to “stressors”, such as air pollutants, causes changes in the structure of DNA. Specifically, stress-exposure can change the number and location of methyl groups that are attached to DNA, which can subsequently affect gene expression. In other words, environmental conditions can determine which genes are switched on or off and the level at which they are expressed. Patterns of gene expression subsequently influence the establishment of characteristics or traits, for example body size and immune responses. Thus, DNA methylation may mechanistically link environmental conditions and observable characteristics of an individual.
In particular, the environment experienced during early life is known to be very important, in both humans and animals, for determining fixed life-long characteristics relating to, for example, body size, personality and health. Changes in DNA methylation are proposed to be the mechanistic link between the early-life conditions and determining later-life health and survival. Through this study, we seek to better understand how urban-dwelling birds are affected – both positively and negatively – by exposure to urban “stressors”. Understanding how and why exposure to stressors in towns and cities may affect health and survival of birds is important for progression of our knowledge of animal biology, implementation of effective conservation measures, and improving our own health and wellbeing.
