So how do we even set about finding these well camouflaged, nocturnal owls? Basically by heading out in their mating season and listening for their distinctive hoot, a resonant, two-syllable “ooh-hu” sound. Between January and March the male calls the female in the twilight hours. Armed with that knowledge, the founder and head of the LVB owl group Daniela zum Sande asked us all to help out with a large-scale ‘eavesdropping operation’ along the Isar. We were just two of a total of 60 volunteers who signed up to patrol the riverbanks over the course of several freezing cold, wintry nights. Our job was not only to listen out for individual animals, but also to note the direction of their call, because that provides a clue as to the location of the nesting site.
Eagle-owl expert Günther von Lossow from the ornithological institute run by the Bavarian Environment Agency in Garmisch-Partenkirchen identified a total of 31 suspected eagle-owl territories along the Isar. Volunteers were chosen to monitor each of these areas. Axel and I were assigned to the Wolfratshausen-Schäftlarn section south of Munich. After a year of observation, it became clear that eagle-owls were indeed living in at least nine of the 31 areas, with a chick being reared in three of them.