Bats produce high frequency echolocation calls to collect information about their surroundings. These calls can be detected with ultrasonic acoustic recorders. MARECO uses different types of detectors (i.c. Batcorder, SM3 song meter) to study bat activity in offshore wind farms, and equally so in proposed wind farm sites on land.  We developed experience in field campaigns by installing recorders on offshore platforms, at the base of wind turbines and even at nacelle height of wind turbines. Pre-construction surveys on land are conducted with hand-held detectors. Recordings are processed and visualized with the help of dedicated software programs.  Species identifications are further verified and validated by bat experts of the MARECO team.