East meets west

: dispersal in the Peregrine Falcon Falco peregrinus

Abstract

The peregrine is a pan-global species, found in most habitats apart from the polar regions and deserts. Over the past 30 years it has been recovering from the direct and indirect effects of organo-phosphate pesticides which severely depleted their populations across Europe and North America. In Britain, the peregrine’s population dropped below 400 pairs. While there are now over 1700 breeding pairs in Britain, alongside an unknown floating population of non-breeding birds, little has been published on the species’ behaviour and in particular their post-natal dispersal in lowland England. This is the first study of its kind that outlines the movements of peregrines in southwest England. It reveals that female peregrines disperse with a north-east bias, dispersing into areas of lower peregrine occupation, and travelling longer distances than males. They remain in areas of low altitude with many being recovered at wetland, agricultural and semi-natural habitats. It is likely many of these birds are non-breeders, especially as only half the number ringed at urban locations were recovered in an urban environment, while just a fifth originally ringed at inland quarries were recovered at subsequent quarries. Peregrines show strong fidelity to the type of nesting habitat where they hatched and therefore these figures suggest many of the recovered birds were not yet on a territory, were nesting on nearby rural pylons or sighted while foraging away from a nest site. Overall, the results suggest that peregrines have the potential to continue occupying suitable and vacant habitats across Britain and that dispersing birds from the southwest of England are helping to spread the peregrine population into areas where they have been absent or in low abundance for a long time.

Date of Award	24 Mar 2020
Original language	English
Awarding Institution	The University of Bristol
Supervisor	Sean A Rands (Supervisor) & Innes C Cuthill (Supervisor)