Asking for ecological knowledge at work, we find many qualitative ecological statements, mainly relating to the area of autecology or species and population ecology, belonging to higher plants and animals long before the creation of the special field in the 19th century. This paper will call attention to the early observations of ecological phenomena since the 16th century. It states that observations on climatic factors, air temperature, the quality of surroundings and of the soil, on the time of florescence and fructification etc. did not arrive incidentally, but were based on the fundaments of empirical sciences. The empirical research was performed in combination with theoretical presuppositions being characteristic of the 16th and 17th century natural history. Examples of two important empirical fields of this time will be evaluated: Some results of European overseas travellers and their explorations in very different regions of the world, the attempts to transfer living animals over long distances and to cultivate plants in botanic gardens will be discussed. By analyzing the reports of travelling naturalists describing their observations made in foreign countries, documenting the new kind of field research including elementary experimental methods, we find out that authors, trained earlier in scientific fields, based their observations and descriptions on the principles of the traditional European science. The Aristotelian categories locus and tempus, renewed under others by methodologies and used as rules of conduct by the authors of European Renaissance herbals and zoological books during the Pre-Linnaean period, led the naturalists to observe the living space and the life periods of living objects. Thus, that means in sum, they paid attention to ecological living conditions.