Bats and wind energy in woodland III

The aim of the research is to find out whether bat colonies suffer significant disturbance due to the operation of wind turbines in woodlands and whether wind turbines cause loss of habitat beyond the actual cleared area. Disturbance effects of this kind cannot be ruled out, particularly for passive acoustic gleaning species such as the brown long-eared bat and Bechstein's bat. For these species, operation of wind turbines could lead to the colony centres being moved away from the turbines and avoidance of a considerable area of woodland around the turbines which would therefore be lost as a hunting habitat. In this case, compensatory measures would have to be planned covering a larger area.

The following research questions need to be answered in detail:
•    After the construction of wind turbines, do the colony centres and/or activity areas of bat colonies move due to disturbance effects? How far away from the turbines can these effects still be detected?
•    Are typical compensatory measures (e.g. putting up bat boxes) accepted by the colonies? How might the effectiveness of the measures be increased?
•    Under what conditions (e.g. distance of the colony from the WT sites) can it be assumed that a local population will be endangered or significantly disturbed by the construction and operation of wind turbines?

Methods

For the after surveys, sites will be used where before surveys of the brown long-eared bat have already taken place in the precursor project during two years. At these sites (a planned wind farm and a reference site), roost and habitat use as well as colony sizes will be intensively investigated in two consecutive years and compared with the results before the construction of the wind farm.

In addition, colonies of the Bechstein's bat will be investigated in two existing wind farms using similar methods. As one of these wind farms has been in existence for a long time, this study also makes it possible to determine long-term effects on bat colonies. However, as there are no comparable surveys available for these investigations prior to the construction of the wind farm, it will instead be checked whether the use of space and roosts corresponds to the pattern to be expected based on the habitat configuration. In addition, it will be examined whether the operation of the wind farm influences the behaviour of the bats.