For my MSc thesis, I am examining the effect of an increasing Eagle Owl (Bubo bubo) presence on the breeding success of the Peregrine Falcon (Falco peregrinus). After a pesticide-induced population crash in both species during the last century, the Peregrine Falcon population increased and stabilized at lower population levels. Around 2010 the population started to decrease again. This thesis aims to determine whether the decrease in population size is due to the range expansion and renewed presence of the Eagle Owl or other cryptic causes, such as pesticides.
To understand the drivers behind this trend, I will analyze a long-term dataset collected through intensive monitoring of breeding cliffs in Valais and Vaud. This dataset includes presence-absence records and breeding data for both species, collected over more than 10 years across multiple sites. Using multi-season occupancy models, I aim to disentangle the potential effects of the Eagle Owl on the Peregrine Falcon.
In addition, I explore how to optimize monitoring strategies for Peregrine Falcons. Building on my BSc thesis, which examined how visit duration and structure affect detection probability, I collected time-to-detection data during this year’s field season. I will analyze this separately with time-to-detection occupancy models to inform more efficient survey designs.
