“After the red kite virtually disappeared in the 1950s, we now find more than 3,000 breeding pairs in Switzerland,” says Van Bergen. Because the causes of this exceptional increase were unclear, the Swiss Ornithological Institute launched a large-scale investigation in 2015. “This was one of the largest bird of prey surveys in the world,” says Van Bergen proudly.
With the research, Van Bergen wanted to better understand the life of the red kite. “We have tagged 584 birds in the provinces of Bern and Fribourg. This allows us to study the individual migratory behavior of the different birds.” The Swiss scientists also installed nest cameras to monitor, for example, the nesting behavior and fledging of the red kite.
Waiting forever for a territory
“We found, among other things, that young individuals often return to their place of birth and stay within a radius of about fifty kilometers,” says Van Bergen. Obtaining a territory is not that easy. “Because older birds defend their territories fanatically, young birds sometimes have to wait seven to eight years until they have their own place.”
Block of cheese
Here, human food scraps are also an important food source. For example, red kites in Switzerland are regularly fed or pick food from compost heaps. “For example, during my move we had put the food outside and a red kite tried to grab the block of cheese. They also like a piece of cheese.”