Repopulation of the former breeding range: spatio‐temporal patterns and drivers of reproduction in the Peregrine Falcon (Falco peregrinus) population in Hungary

The disappearance of the breeding population of Peregrine Falcon Falco peregrinus from Hungary in 1964 is likely to have been caused by extensive agricultural use of organochlorine pesticides. After proving harmful to humans and wildlife, organochlorine pesticides were banned in North America and many European countries, leading to a recovery in Peregrine populations and other raptors in most parts of the world. In Hungary, Peregrines returned as a breeding species in 1997. Using 26 years (1997–2022) of monitoring data, we investigated spatio‐temporal patterns in site occupancy and reproductive success during population recovery. We found that: (i) Peregrines initially re‐occupied traditional territories in mountainous and forested regions where suitable nest‐sites were available on cliffs and in quarries; (ii) the Peregrine population then slowly expanded to lower elevations, predominantly agricultural areas, where they nested in trees and in artificial nest‐sites on pylons; (iii) the overall mean (se) probability of successful nesting was 0.713 ± 0.02 and the average brood size (number of young per successful nesting attempt) was 2.56 ± 0.04, with spatial and temporal variation in both measures of reproductive success; (iv) March precipitation had a negative effect on brood size in the wettest region; (v) higher greenness levels in February negatively affected nesting success in the least forested region; and, finally, (vi) Peregrines breeding in artificial nestboxes on pylons had higher nesting success than pairs breeding in natural nests. Our results suggest that the general recovery pattern of Hungarian Peregrines was similar to those observed in other parts of Europe, but also highlight spatial variation in demographic parameters.