Dissertation defence (Biology): MSc Gian Luigi Bucciolini

MSc Gian Luigi Bucciolini defends the dissertation in Biology titled “Environmental heterogeneity and population variation in tawny owl: Life history, behavioural and ecological perspectives across Europe” at the University of Turku on 2 October 2026 at 12.00 (University of Turku, Natura, Lecture room XI, Turku).

Opponent: Associate Professor Petra Sumasgutner (University of Vienna, Austria)

Custos: Professor Jon Brommer (University of Turku)

Summary of the Doctoral Dissertation:

Animals living in different parts of the world face very different environmental conditions. Climate, forest types, food availability and the length of the seasons can all influence how animals live and reproduce. Understanding how animals respond to these differences is particularly important as environments continue to change.

In my PhD, I studied how tawny owls (Strix aluco) differ across Europe. Tawny owls live in a wide range of environments, from the northern forests of Finland and Sweden to the more temperate forests of central and southern Europe. This makes them a particularly useful study species for understanding how animals respond to different surroundings. I combined long-term information on reproduction with observations from infrared cameras and analyses of the owls’ diet.

The results show that tawny owl populations differ in several important aspects of their lives. The number of offspring produced by females over their lifetime varied between populations. I also found that in some populations, darker owls had higher reproductive success, while in others lighter owls did better. This suggests that the same characteristics can be beneficial in one environment but less beneficial in another.

I also investigated how tawny owls use nest boxes outside the breeding season. Their use of nest boxes differed between populations and seasons. Owls were most often found inside nest boxes during the daytime and in winter, but the amount of use varied considerably between populations. Nest boxes were used relatively often in Italy, showing that owls living in different environments can use the same resource in different ways.

During the breeding season, I studied the diet and daily activities of tawny owls in Finland and Sweden. Although the overall amount and variety of food consumed were similar, the types of prey differed between the two populations. The owls also changed how they divided their time between staying inside the nest box and being outside as their chicks grew. The activity time mainly took place at night.

Overall, this dissertation shows that tawny owls combine consistent behaviours with the ability to adjust to local environmental conditions. Populations of the same species can therefore live and reproduce in different ways depending on where they live. This flexibility may be especially important as climate and habitats continue to change.

By showing how reproduction, behaviour and food use vary among tawny owl populations across Europe, this research improves our understanding of how widespread species can persist in different environments. It also highlights why populations of the same species may respond differently to environmental change. This knowledge can help improve predictions of how wildlife will be affected by future changes in climate and habitats and contribute to more effective conservation of animal populations.