Animal observation can be improved significantly with the help of modern technology. Especially in the case of bats this has been quite difficult in the past, because they are active only at night, and they must not carry a transmitter heavier than 10% of their own body weight. The progress of micro electronics has made it possible to build complete computers that fulfill these requirements. They do not just send beacons, but data. The ground station receives these data and evaluates them. That begins with the position of the bat, continues with meetings with other bats (of particular interest: mother and child), and ends with body temperature, pulse, and other biosensors. The data are collected and evaluated as a whole. Unfortunately, they are rather imprecise and also flawed. So it is a substantial issue to clean them first. The far-end goal of the project is to capture only data actually needed for the evaluations given, thus saving energy and allowing to observer the bats even longer.