||Basing on case studies in South-West- and North-East-Germany techniques of hidden observation such as observing visitors behaviour with binoculars from far distance are discussed. Their origin in ethological field studies is reflected, ethical aspects are mentioned and the conditions to produce valid data are qualified. Especially in case of analysing non-legal behaviours direct questionnaires are often not be able to clear whether serious damages in the protection areas are resulting or not. Also the intentions of “breaking the rules” cannot be reflected totally by socio-empiric methods. On the other hand behaviour observations require a lot of time and energy and should be limited on serious indications because of ethical aspects. So it is necessary to describe conditions and cases, where observing techniques can be implemented successfully.