Population trends of Peregrine Falcon in Northern Spain – Results of a long-term monitoring project

Abstract

We monitored Peregrine Falcon (Falco peregrinus) population in Bizkaia, Northern Spain, during two decades (1998–2017). Our population increased from 34 to 47 territorial pairs, as did other European populations until the first years of the 21st century, and then declined until 34 territorial pairs in 2017. The combination of catastrophic events (Prestige oil spill), increasing rain in winter and spring, and direct and indirect mortality factors significantly affected incubation onset, productivity and population stability, which in turn could impact on the floater population. Rain in February significantly affected incubation onset, which showed a slight positive trend during the last decade. Juvenile females laid 12 days later than adults, and each adult female started incubation in the same dates every year. However, the proportion of juvenile females did not significantly increase as might have been expected. Moreover, productivity was inversely related to incubation onset dates. Rain in April and May also affected productivity, and combined with short term extreme weather events determined a decreasing productivity during the last decade. Moreover, apart from human persecution (which caused 40.30% of the known deaths of Peregrines), we found 18 cases of breeders affected by infectious diseases, also related to weather. The combined effects of these factors, and the low availability of adequate nesting sites, negatively affected (i) territorial populations, (ii) productivity, and (iii) floater population, which in turn also determined territorial population and productivity.

Spatio‐temporal variation in post‐recovery dynamics in a large Peregrine Falcon (Falco peregrinus) population in the Jura mountains 2000–2020†

“…of the Peregrine, the European Eagle Owl Bubo bubo, illegal persecution, human disturbance and perhaps also delayed density-dependence. In contrast, we believe that we can rule out increased spring precipitation (Carlzon et al 2018, Zuberogoitia et al 2018 or declines in the prey base. We discuss each of these in turn.…”

“…2018), as has a study in the Basque country (Zuberogoitia et al . 2018). Nevertheless, such findings are still relatively rare in the worldwide success story of this species and similar former pesticide victims.…”

“…Our finding of some severe post-recovery declines in a Peregrine population is not entirely unique. For instance, a recent trend assessment in Great Britain has identified declines of Peregrines in several regions as well (Wilson et al 2018), as has a study in the Basque country (Zuberogoitia et al 2018). Nevertheless, such findings are still relatively rare in the worldwide success story of this species and similar former pesticide victims.…”

“…Between the 1950s and the 1970s, its populations crashed, sometimes to regional extinction, in virtually every place from where adequate data exist (Hickey 1969, Fyfe et al 1976, Cade et al 1988, Ratcliffe 1993). However, around the turn of the century levels of many populations were back to normal (Cade et al 1988, Cade & Burnham 2003, Sielicki & Mizera 2009, Bruggeman et al 2015, 2016, Ambrose et al 2016, Zuberogoitia et al 2018, Kéry & Zuberogoitia 2020) and sometimes became even greater than recorded at any time before the pesticide crash (Horne & Fielding 2002, White et al 2013, McGrady et al 2017, Beran et al 2018, Prommer & Bagyura 2018, Swem & Matz 2018, Wilson et al 2018, Newton 2021). As a result, the threat category of the Peregrine in many national Red Lists has repeatedly been changed to reflect a reduced or even eliminated threat of extinction (Mesta 1999).…”

Review of the development of the Peregrine Falcon(Falco peregrinus)population in Hungary between 1997 and 2018

“…The dynamics of Peregrine Falcon population in Hungary between 1997-2018 1. ábra A magyarországi vándorsólyom-állomány változása 1997 és 2018 között that Hungary is not very rich in natural cliffs and quarries, and the best quality ones have already been taken by Peregrines or Eagle Owls (Bubo bubo). It can also be an indication of a population decline in the coming years as it occurred in Northern Spain (Zuberogoitia et al 2018), in Switzerland (Kéry et al 2018) and in France (Monneret et al 2018).…”