King's College London

Changes in peregrine falcon diets during COVID-19 lockdowns highlight the impact of human behaviour on urban predators. The findings are from a new study co-authored by King’s researchers published in the British Ecological Society journal, People and Nature.

Researchers from King’s College London and University of Bristol found that during lockdowns, peregrine falcons in London were forced to change their diet away from pigeons since fewer of these birds were being drawn in by human food supplies such as discarded food waste or direct feeding.

Brandon Mak, a PhD student in the Department of Geography who co-led the study with Ed Drewitt from the University of Bristol, said: “Our results indicate that peregrines in larger, highly urbanised cities like London may be more dependent on, and hence more vulnerable to changes in, human activities which support their prey populations, particularly feral pigeons.”

In the study, citizen scientists, including students from King's, used online live streams to monitor 31 peregrine falcon nests in 27 UK cities over the course of three breeding seasons, the first of which took place during pandemic restrictions.

In London, peregrines took a lower proportion of pigeons as prey (-15%) and replaced them with starlings (+7%) and parakeets (+3%). However, in other cities, pigeons remained the dominant prey.

The changes to peregrine diets observed in the study raises questions on how pest control may affect falcons and other predators that depend on ‘pest’ species. For example, the population of the prey bird Northern goshawk in Poland almost halved when farmers stopped rearing domestic pigeons and other poultry that would have been their prey.

Management of pest species and their food sources are usually human driven. Therefore, reductions in pest species, like pigeons, can force raptors to switch prey or forage further away from their nests. This can in turn result in poorer nutrition from less ideal prey or a decrease in energy for fitness or reproduction due to the effort spent on hunting.

In the future, the authors of the study hope to contribute towards the Global Anthropause Raptor Research Network (GARRN) which brings together similarly conducted research from the pandemic.

The other co-authors of the study are Robert Francis, Professor of Urban Ecology & Society, and Dr Michael Chadwick, Senior Lecturer in Physical and Environmental Geography, from the Department of Geography.