During the summer of 1995, several wings of bats were found on the nest of a Hobby in the Asserbos in the province of Drenthe (53°00’N, 6°34’E). Considering wing measurements (Table 1) and local habitat characteristics, either Serotines Eptesicus serotinus or Noctules Nyctalus noctua were involved. The latter is more likely, as it normally emerges earlier from roosts than Serotines.