Population trends of the Peregrine Falcon in Switzerland with special reference to the period 2005–2016

Abstract

We study population trends of the Peregrine Falcon (Falco peregrinus) in Switzerland with special reference to the development since 2005 and three study areas, South West Switzerland (4,993 km2, 1960–2015), the Northern Jura mountains (3,270 km2, 2005–2015) and the Canton of Zurich (1,748 km2, 2002–2015). We used dynamic occupancy models, which allow the territory-specific extinction and colonization parameters – the demographic rates (at the territory level) underlying a population trend – to be estimated. The Swiss peregrine population has developed in line with trends observed in many other countries and regions in North America and Europe: after the pesticide-induced collapse between the 1950s and 1970s, the population largely recovered up to the turn of the millennium. However, in recent years, we detected significant declines again: in SW Switzerland, the population decreased from 51 to 33 pairs during 2008–2015 (-35%), in the N Jura from 70 to 40 pairs during 2009–2015 (-43%) and in Zurich from 6–7 to 2–4 pairs during 2010–2015 (-50%). In the same time, the local extinction rate in the three study areas (more than) doubled from (0.05) 0.1 to 0.2, while the colonization rate dropped from 0.3 to 0.1 in one of the areas, while no change was detectable in the other two. We discuss two factors responsible for these strong, recent declines of Swiss peregrines: (1) predation by Eagle Owls (Bubo bubo) and (2) direct and illegal persecution by humans. In addition to these two factors, growing human disturbance (e.g. through climbers, bird photographers, paragliders, hikers, geocachers, etc.) and fatalities due to collisions with man-made structures (power lines, glass, wind turbines, etc.) are also suspected to contribute to the population decline.

A summary of intentional poisoning of Peregrine Falcons in Switzerland during the last decade

“…The few cases of poisoning may seem too sporadic to have an influence on the Peregrine Falcon population. But firstly, we certainly detect only a proportion of cases and secondly as Altwegg et al (2014) and Kéry et al (2018) could show in their publications, given the low numbers of birds composing the population, removing only a few individuals can lead to a critical decline in the population level.…”

“…As in many other regions in Europe and North America, the population of the Peregrine Falcon recovered in Switzerland after the collapse between the 1950s and the 1970s. After the turn of the millennium the situation changed: in the South West part of Switzerland, the population decreased 35% between 2008 and 2015, in the Northern Jura Mountains 43% between 2009 and 2015 and 50% in the canton of Zurich between 2002 and 2015 (Kéry et al 2018). As causes for the decline, Kéry et al mention the predation by the Eagle Owl, whose populations are recovering in Switzerland, and the persecutions by humans, i.e.…”

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

“…Here, and unlike in Kéry et al . (2018), we only used data from the Jura part of the Jura Sud. The third population study (‘Jura Nord’) was located in the central, northern and eastern parts of the Swiss side of the Jura mountains and was launched in 2005 by the first author.…”

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).…”

“…In other cases, populations are stable (Pasquier et al 2018) or follow the changes of distribution patterns of prey species (Nygård & Reinsborg 2017). In some parts of the European distribution range, however, the recovery process was followed recently by a decline (Kéry et al 2018, Monneret et al 2018.…”