Natural habitats are disappearing at record speeds, and our world is becoming increasingly urbanised. Recently, researchers started exploring how cognitive abilities (the mechanisms by which animals acquire, process, store and act on information from the environment) may allow animals to adapt to urban environments. Many of these studies revealed cognitive differences between
urban and non-urban dwelling animals and linked these to informational challenges related to the highly dynamic nature of urban environments. Here we hypothesize that urban diets also contribute to such cognitive differences. Although lab-based studies indeed showed important effects of diet on the development of cognition, this idea so far received little attention in the urban cognition literature. We will address this important knowledge gap by combining theoretical frameworks and methodology from psychology, ecology, and microbial sciences. Furthermore, as most of the previous work linking urbanization with cognition was correlational in nature, we will supplement our interdisciplinary approach with a powerful combination of controlled laboratory experiments and measures of cognition in the wild. Specifically, we will test how high-fat high-sugar diets (WP1), and the gut microbiome (WP2) shape cognition in three domains that are considered crucial for survival in urban environments, namely spatial learning, inhibitory control, and social learning. We will use feral pigeons, a species that thrives in urban environments, and whose diet varies widely between urban and non-urban environments, as our model species.