Population monitoring

One of our most important tasks is monitoring the population of Barn Owls in our study zone. With the help of the Swiss Ornithological Institute and thanks to the many artificial nestboxes that have been installed, every year we carefully monitor each brood. These nestboxes are vital for the owls who are otherwise lacking in natural breeding sites.

Installation of nestboxes

Our study zone is located in Switzerland and extends from Lausanne to Morat, covering areas in the canton of Vaud and Fribourg. Each year, researchers from our group and from the Swiss Ornithological Institute regularly visit the nestboxes of this region. Currently, there are about 400 nestboxes installed, and the number continues to increase. Installing nestboxes creates new nesting sites for Barn Owls, an essential measure for the conservation of the species. Traditionally, these owls reproduce using cavities in old trees or cliffs. They then moved into human habitations, but our renovations often deprive Barn Owls of these breeding sites. Common Kestrels will also willingly reproduce in artificial nestboxes.

Follow up and study

During the breeding season, we regularly check each nestbox for new eggs, and then we monitor their development. Using DNA analyses, we’ve been able to establish a genealogy of the Barn Owls in our study zone for over 25 years. What’s more, each owlet is given a ring (provided by the Swiss Ornithological Institute) on which is engraved an ID number for the bird. It will keep this ring for its entire life. We take advantage of the ringing stage to track the growth of the nestlings as well as gather various essential information for monitoring the species, like the number of eggs and owlets.

When the young owls are ready to leave the nest, usually at about two months, we visit the nestbox for the last time. All the owlets are measured: beak, wing, feathers, weight, colors, etc. In addition to furthering our research, these data enable us to track the number of owlets who reach maturity, as well as monitor overall headcounts and the health of the population.