Progress in Signals and Telecommunication Engineering Anton Gradišek, Candace Galen, Nicolas Cheron, Janez Grad, David Heise 7 2 2018 http://www.dline.info/pste/fulltext/v7n2/pstev7n2_1.pdf We present initial results of the study where we used microphones, placed in front of nest boxes, to monitor daily foraging activity of bumblebees. Sound recordings were analyzed using a custom-made computer algorithm which detects flight buzzing sounds coming from arrivals or departures of individual bees. In addition, the algorithm distinguishes between arrivals and departures. We show examples of daily activities for three species (B. pascuorum, B. humilis and B. hypnorum), each was monitored over the course of one day. This paper presents initial results of a longer study where we plan to systematically investigate the activities of bumblebees in various circumstances.