Abstract: We developed a biorhythmical method to assess behaviour patterns and to evaluate living conditions of animals. All kinds of continuous and equidistant long-term recordings of behaviour are suitable for this method. As simple behavioural parameters, such as motor activity, can be conveniently recorded by telemetry from wild animals now, it is possible to investigate stressors by analysing its biorhythmic structure. It is the purpose of this report to describe the basic idea, and the procedure, and to give some examples of application measured on Przewalski horses in an Semireserve.