Bat behavior

Investigation of connectivity and behavior of bats migrating over the sea for a more accurate assessment of the effects of offshore wind turbines (Batmobile)

Naturschutzbund Deutschland, Landesverband Mecklenburg- Vorpommern e.V.

Within the scope of the project funded by the Federal Agency for Nature Conservation (BfN), factors are to be identified which increase the risk of collision and killing for bats with offshore wind turbines.

  • On the basis of bioacoustic recordings and telemetric examinations of individual flight routes, the extent to which densification areas (such as flight corridors) exist should be checked. These are listed below as a basis for spatial planning avoidance measures.
  • Behavioral observations (departure observations, offshore behavior observations, telemetry) and acoustic behavior determinations (especially acoustic altitude monitoring) are intended to investigate how bats behave offshore during the train and on vertical structures and whether, for example, exploratory behavior occurs, which could significantly increase the risk of a collision. On this basis, technical avoidance measures such as Operating algorithms (shutdown algorithms) are developed.

Based on the results, standard methods for the basic investigation and monitoring of bats in concrete wind farm projects are to be developed and formulated. These could directly integrated into the standard investigation concepts of the licensing authorities.

The Federal Agency for Nature Conservation is funding the FKZ 3519 86 1300 project from December 2019 to January 2023 with funds from the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.

Activities and goals

Bioacoustic continuous recording

The present findings on the offshore bat pull provide first indications of the existence of densification areas. However, the measured activities of individual locations sometimes vary considerably over the years. A high ecological validity can only be achieved through the acquisition of longer data series and an expansion of the investigation network. In the course of this, the bioacoustic tests that have started on FINO 1 are to be continued.

Altitude monitoring

Little is known about the behavior of bats migrating across the sea. However, these have a major impact on the actual collision risk on offshore wind turbines. For wind energy plants on land, it is known that bats show strong exploratory behavior on them and, for example, move within a very short time from a ground level flight level into the rotor area. Such attraction effects lead to a greatly increased risk of collision due to the increased probability of being in the rotor area. The few behavioral observations so far carried out in the offshore area indicate that similar behaviors could also occur on offshore wind energy.

In addition to direct observation, automated acoustic height monitoring offers a good opportunity to record behavior on vertical structures. For this purpose (on the measuring mast of FINO 1) acoustic detection systems are installed at different heights. The acquisition data allow conclusions to be drawn about bat activity at the various altitudes. Under offshore conditions, where comparatively few calls are recorded compared to recording on land, in most cases calls are also assigned to individual individuals. This makes it possible to derive the flight altitude and to prove the exploration behavior of individual individuals on the vertical structures.