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Diet variation and breeding success of tawny owls in different habitats

Aune, Johan (2021) BIOK01 20211
Degree Projects in Biology
Popular Abstract
Tawny owls and food for thought

I have been focusing on tawny owls, which are a species of owls that you can find in a wide range of habitats. Everywhere from open fields to cities, they have found a way to survive, hunt for food and settle down. A very adaptable species. I was interested in finding out just what do these birds of prey eat, and how does that affect how well they survive, in different types of landscapes. So, I set out to find out what they eat and how that changes in different habitats.

Small mammals can be found both in open landscapes as well as in deciduous forests. Especially open landscapes with lots of edges between tree lines and fields are appreciated by rodents. Deciduous forests, with lots of beech, is also... (More)
Tawny owls and food for thought

I have been focusing on tawny owls, which are a species of owls that you can find in a wide range of habitats. Everywhere from open fields to cities, they have found a way to survive, hunt for food and settle down. A very adaptable species. I was interested in finding out just what do these birds of prey eat, and how does that affect how well they survive, in different types of landscapes. So, I set out to find out what they eat and how that changes in different habitats.

Small mammals can be found both in open landscapes as well as in deciduous forests. Especially open landscapes with lots of edges between tree lines and fields are appreciated by rodents. Deciduous forests, with lots of beech, is also a popular habitat for small mammals.

During breeding season, the tawny owl’s favorite food is just that, rodents. If there are lots of mammals around their nests, they can raise larger chicks faster. Having your offspring grow quickly is of course very advantageous for all wild animals. If there are fewer small mammals around, the owls can also hunt for insects or even small birds, though that is not their firsthand choice.

All owls regurgitate pellets, which contain indigestible prey remains such as bones. By sorting through these pellets, and searching for remains of their prey, I could figure out just what the owls in each nest had eaten during the breeding season. The chicks were also weighed, which provided a good indication of how well the nest and its owl family was faring. Better food in the area, more healthy chicks that grow faster, and therefore weigh more. By comparing the food that they eat, and how much the chicks weigh, we can see which habitat the owls survive the best in.

What I found out was the owls caught a lot more mammals in the open landscape, which is in line with what I expected. I could also see that the owl families who caught the most mammals also had the chicks that weighed the most. This is important to consider when caring for forests and fields in order to protect our owls. Healthy owl populations around our agricultural fields help us keep pests under control for example. Without them, rodents and other small mammals would be able to cause much greater harm to farmers around the world.

Bachelor's Degree Project 15,0 credits BIOK01
Department of Biology, Lund University

Supervisor: Hannah Watson (Less)
Please use this url to cite or link to this publication:
author
Aune, Johan
supervisor
organization
course
BIOK01 20211
year
type
M2 - Bachelor Degree
subject
language
English
id
9059895
date added to LUP
2021-06-30 09:58:40
date last changed
2021-06-30 09:58:40
@misc{9059895,
  author       = {{Aune, Johan}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Diet variation and breeding success of tawny owls in different habitats}},
  year         = {{2021}},
}