Hunting success and efficiency of an urban Peregrine Falcon (Falco peregrinus) during the low light season in south-west Norway

Abstract

Cover photo: A Peregrine Falcon Falco peregrinus landing on a radio antenna. Photo: Bjarne Emil Time.

In November-December 2019, a Peregrine Falcon Falco peregrinus hunted close to the center of Bryne, a small town in southwest Norway. During winter, several thousand corvids normally roosted together in the city’s park area. The hunts took place in the dark, after sunset and before sunrise. In this 30-day study, the falcon used a sit-and-wait strategy to hunt roosting corvids. The hunt started each time from the top of a 43 m high antenna near to the park and my apartment. The falcon then brought prey items to a balcony on a tall office building in the city centre, and to the same plucking and eating site after each kill. Sensitive cameras documented the activity of the falcon and its prey which were always Jackdaws Corvus monedula. One camera was mounted by the antenna and two cameras were deployed on the balcony. The attacks were registered as successful if the falcon returned with prey, or otherwise as unsuccessful. The falcon made a total of 42 attacks. A subset of 18 attacks ended with a return to the balcony, of which 13 were successful, resulting in a hunting success of 31% (13/42). Overall, 54% of all kills occurred in the dark before sunrise, and most of the prey were killed in December (77%). The ratio of time spent on successful hunting to total hunting time was 79 to 308 minutes, giving a hunting time efficiency of 26%. On average, the falcon used 6 minutes per successful kill, with a range between 1 to 16 minutes.