The little owl, Athene noctua, is a small nocturnal owl and is classified as an endangered species on the German Red List.
In recent years the existing population of little owls has successfully been stabilized in the south-west of Germany.
And in some places, the numbers of little owls are even rising.
Suitable Habitat for Little Owls
In neighboring northern Switzerland there is still no established population of little owls, even though habitat conditions seem suitable for the species.
Now, a team of researchers headed by Severin Hauenstein from the Department of Biometry and Environmental Systems Analysis at the University of Freiburg studied whether juvenile little owls from Germany could reach and recolonize northern Switzerland.
Lead researcher Hauenstein says it’s difficult to predict how animals will disperse.
Exploring Dispersal Potential of Little Owls
Hauenstein and his colleagues from the Swiss Ornithological Institute in Sempach, Switzerland, the German Centre for Integrative Biodiversity Research Halle-Jena-Leipzig (iDiv), the Helmholtz Centre for Environmental Research in Leipzig and the University of Regensburg developed an individual-based computer model.
Using simulations, researchers can assess whether individuals from the currently expanding little owl populations in south-western Germany can migrate to suitable habitats in northern Switzerland.
Intensive farming and a steady loss of habitat have caused virtual extinction of the little owl in Switzerland.
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Movement Behavior Analyzed
The movement-behavior parameters in the model estimate using Bayesian statistical inference based on radio telemetry data of juvenile little owls.
Researchers learned female juvenile little owls move more directionally and fly longer distances during the dispersal phase, while males take longer rests, and show a greater attachment to suitable habitat.
Recolonization Possible With Restrictions
Hauenstein explains that the findings indicate that the little owl’s natural recolonization of northern Switzerland is generally possible, however, there are restrictions.
“Fragmented urban areas in particular, such as those around the tri-border area near Basel, appear to limit the movement of juvenile little owls drastically,” he says.
Hauenstein says little owls avoid forested areas because their natural enemy, the tawny owl, resides there.
He says little owls also avoid higher altitudes such as the Swiss Jura, the Black Forest, and the Swabian Alb.
The scientists highlight existing but narrow dispersal corridors, such as the lower Aare valley or the Fricktal south-east of Basel.
He adds that by improving the habitat for the birds through agricultural extensification and nest box provisions, it may be possible to expedite the recolonization of northern Switzerland by the little owl.
Read the findings of this research in Ecological Applications.