The preservation of decorated caves is a great challenge that has been reinforced by the microbial crisis occurring at emblematic sites such as the Lascaux and Altamira caves. To date, little is known about the microbial behavior of caves. One difficulty is that the term ‘cave’ covers a wide variety of sites and structures. Past studies concentrated on caves with microbial disorders and were generally carried out in a time frame that was too short to gain an adequate picture of healthy microbial behaviors, the sine qua non of detecting potential imbalance. The aim of this study was to determine whether models of aerobiological behavior could be identified in several decorated caves. We monitored aerial rates of fungi and bacteria in five decorated caves of the Gard department (France) for periods of two years or more. A model behavior was identified in each cave. These models were cave dependent, and were also season-dependent in some caves. Following our fungal results, we suggest separating the caves into two groups. The caves which were strongly affected by the external environment throughout their entire length are the “non-self-purifying caves”. The caves which were only affected by external environment at the entrance are the “self-purifying caves”.