How urban is an ‘urban-dwelling’ Peregrine?

ABSTRACT Information is limited regarding the habitat use and home range of urban-dwelling Peregrine Falcons Falco peregrinus in the UK. However, understanding their spatial and temporal behaviour is necessary if we are to explain their success in urban environments and recent declines in rural areas. We tracked a GPS-tagged adult female Peregrine known as ‘SY’, in Salisbury, Wiltshire, between 2017 and 2019. Across the study period, she spent just over half her time within 1 km of her nest on Salisbury Cathedral, with the remainder spent mostly in improved grassland and arable habitats outside the city. Her home range expanded between the nestling period and when the young had fledged, and expanded further when she was evicted from her breeding territory by a new pair of Peregrines. SY’s month-by-month home ranges were compared to those of GPS-tagged Peregrines wintering in other parts of the world to indicate how typical or unusual her home-range sizes were: the results showed that SY’s 50% kernel-density-estimated (KDE) home range was relatively small (0.15–5.6 km²) compared to other urban-dwelling Peregrines, while her 95% home range was typical. Notably, a tiny fraction (0.2%) of her location fixes were from >1000 m above ground level, including one at 4259 m agl. These findings demonstrate how one particular urban-dwelling Peregrine’s home range varies seasonally and encompasses both urban and rural environments.