Pathogens: From Feeders to Flocks

Feeding wild birds is one of the most popular ways people engage with nature. Many do it out of care for wildlife or a desire to feel closer to nature. Yet, while bird feeding is often seen as a harmless or even helpful activity, its actual effects on wild bird health are still unclear. Feeding stations attract large groups of birds, sometimes of many different species, which can make it easier for diseases to spread among them. However, the link between bird feeding and bird health is complex and may involve more than just infection risk. For instance, feeding sites can cause stress if birds must compete intensely for food, or they may lead to poor nutrition if the provided food lacks key nutrients found in natural diets. As bird feeding becomes increasingly common across Europe and beyond, understanding how it affects bird populations has become an important challenge for both science and society. Our project focuses on two familiar garden birds the great tit (Parus major) and the blue tit (Cyanistes caeruleus) both frequent visitors to bird feeders and excellent models for studying how urban living influences wildlife. Using saliva, droppings, and blood samples from around 400 birds collected in Innsbruck and its surrounding areas, where bird feeding practices vary across neighbourhoods, we will explore how supplementary feeding influences bird health and disease. Specifically, we aim to find out: Whether providing food to wild birds increases their likelihood of infection by any of seven common pathogens. Whether these infections negatively affect bird health. Whether the effects of feeding and infection depend on the quality of the surrounding habitat. Whether bird feeding affects bird health in ways unrelated to infection such as through social or nutritional stress. By combining ecological, physiological, and infection data, this project will reveal how human behaviour shapes the health of urban wildlife. It will fill key gaps in our understanding of how feeding affects disease spread, stress, and well-being in wild birds. Beyond its scientific value, the project will also have practical and societal benefits: improving methods to detect pathogens and measure health in wildlife, and informing evidence-based recommendations for responsible bird feeding practices that support wild bird populations.