In this work we present a bat monitoring system for wind farms. The proposed system includes a thermal camera and an ultrasound acquisition device to detect and record bats that come into the detection range of each one of these devices. All events are registered simultaneously with climatic variables and sent to a central database using 3G/4G. The system was designed to allow several monitoring systems to send data to the central server at the same time. We expect this system to allow the determination of climatic conditions that favor bat activity, especially in the proximity of wind turbines, and to use this information to define shutdown strategies to mitigate bat mortality caused by these infrastructures.