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 organo-chlorine pesticides. After proving harmful to humans and wildlife, organochlorine pesti-cides were banned in North America and many European countries, leading to arecovery in Peregrine populations and other raptors in most parts of the world. In Hun-gary, Peregrines returned as a breeding species in 1997. Using 26 years (1997–2022) ofmonitoring data, we investigated spatio-temporal patterns in site occupancy and repro-ductive success during population recovery. We found that: (i) Peregrines initiallyre-occupied traditional territories in mountainous and forested regions where suitablenest-sites were available on cliffs and in quarries; (ii) the Peregrine population thenslowly expanded to lower elevations, predominantly agricultural areas, where they nestedin trees and in artificial nest-sites on pylons; (iii) the overall mean (se) probability of suc-cessful nesting was 0.713 0.02 and the average brood size (number of young per suc-cessful nesting attempt) was 2.56 0.04, with spatial and temporal variation in bothmeasures of reproductive success; (iv) March precipitation had a negative effect onbrood size in the wettest region; (v) higher greenness levels in February negativelyaffected nesting success in the least forested region; and, finally, (vi) Peregrines breedingin artificial nestboxes on pylons had higher nesting success than pairs breeding in naturalnests. Our results suggest that the general recovery pattern of Hungarian Peregrines wassimilar to those observed in other parts of Europe, but also highlight spatial variation indemographic parameters.