How do we study bats (chiroptera) in wind farms?

For years we have been carrying out studies on bats (chiroptera) in wind farms. Its purpose is to establish the composition of the bat community (chiroptera) in the environment of wind turbines as well as to assess the possible effects of the installation of these infrastructures on bat communities in the area.

One of the best ways to study bats (chiroptera) in an area is using an ultrasound detector. Bats use high-frequency calls. This is beyond the reach of the human ear, to build a sound image of their environment. The purpose of ultrasonic detectors is to transform inaudible sounds (with a frequency greater than 20 kHz) into sounds audible to humans.

The acoustic identification of bats (chiroptera) is a fundamental methodology for understanding the distribution of species.

Environmental Ideas considers the following minimum guidelines for studying bats (chiroptera) in wind farms:

• The study of bats (chiroptera) must cover a minimum radius of 10 kilometers around the wind farm. This makes it possible to detect species with large movements in feeding.
• Sampling work must always be carried out within the period of bat activity. In Spain it can be variable, we take as a reference the months of March to November. Exceptionally, other dates will be considered for hibernation sampling in colonies.
• The study of bats (chiroptera) is carried out before the construction of the wind farm and for at least one annual cycle.
• The recordings will take place between sunset and the first five hours of the night.
• The sampling methodology can consist of transects or listening stations at the future positions of the wind turbines and their environment.
• The recordings must be made without continuous precipitation, or excessively strong winds and with temperatures above 10º C.

To carry out studies of bats (chiroptera) in wind farms, you must have the following:

• Qualified personnel. They must also have experience in the field, thus being able to guarantee the correct identification of species to the highest possible level of precision and using appropriate statistical methods of classification.
• Ultrasonic detectors with an expanded time system for recording echolocation calls such as the one you can see in this image.

• Specific software for ultrasound analysis: I'm Bat , BatExplorer, Elekon AG, Avisfot-SASLab by Avisoft Bioacoustics or BatSound from Pettersson Elektronik AB)

• For the identification of the species or genus, published data on the calls of European bat species will be used.

We hope that these general guidelines will help the general public to learn about the importance of carrying out studies on bats (bats), especially in relation to wind energy projects, and thus contribute to minimizing the impact of such infrastructures on populations of these mammals.