1.Camera recording and video analysis have emerged as a successful non-invasive method for collecting a wide range of biological data on many different taxa of animals. However, camera monitoring has rarely been applied to long term surveillance of cavity or box-nesting species and ordinary off-the-shelf cameras are employed. 2.We present methodology and data on the effectiveness of nest box monitoring using a camera system embedded in four “smart nest boxes” (SNBoxes). We applied the SNBoxes to eight Tengmalm's owl (Aegolius funereus) nests in the Czech Republic during a five-month period in 2014. Each SNBox consisted of a pair of cameras with infrared lighting, an event detector, a radio-frequency identification reader, auxiliary sensors, and a 60 Ah 12 V battery to power the whole system. All devices used were centrally managed by an embedded computer with specifically developed software. 3.Using four SNBoxes, we observed owl nesting continually during the incubation, nestling, and fledgling phases, in total 309 days, resulting in 3382 owl video events. Batteries were changed every 6.5 days. A memory of 4 GB was found sufficient to store monthly data. We identified 12 types of male and female parental activities and their timing, the diet composition and frequency of prey delivery, the manner of prey storage, the light intensity at the time of each parental activity, the temperature inside the clutch and outside the box, and the duration of nestling period of each young. We also produced a video on owl nesting for the general public. 4.The SNBox and related methodology show enormous potential as a non-invasive tool for monitoring animals using boxes or natural cavities. The main advantage of the SNBox is the possibility to study both nocturnal and diurnal animal species and great flexibility in use of the software and hardware for different tasks. As a result, the SNBox provides an opportunity for novel insights into the breeding, roosting, hibernating, and food storage activities of a wide range of cavity-living birds, mammals, and reptiles.