In 2008 a nestbox for Kestrels was provided near Kollumerpomp, a village in the province of Friesland. It was occupied in 2008-10, and again in 2020. In some years the exact lay dates of individual eggs were recorded, as well as exact hatch and fledge dates. In 2010, the fledglings disappeared within a few days after fledging, presumably (partly) by predation of Buzzard Buteo buteo.