One of the seemingly "innocent" but often detrimental pressures on the program's bat species is the human presence in important roosts, whether for speleological expeditions, archeological excavations, or other scientific activities or leisure visits. Especially during the period of birth and upbringing of newborns (nurseries, May - July) but also in winter (November-February), in the coldest caves, human presence can lead to mass deaths immediately or in the medium term.