In recent years, thanks to continuous technological development, temperature data loggers have been used to collect data from the breeding progress of birds, which can be used, e.g. to obtain information on the length of incubation breaks, to detect the start of incubation or to record unsuccessful breeding. Temperature data loggers have been used in various types of bird nests, but not in a „closed“ nests such as a burrow or cavity. The study presents the results of using a temperature data loggers in natural nest holes of the common kingfisher (Alcedo atthis). Their nests, which lack substantial insulating structures, are primarily influenced by the relatively stable soil temperature. The temperature of the space inside a nest chamber was measured on a continuous basis with an interval of 1 minute between measurements. The measurement was carried out from egg laying/incubation to a successful leave of the nest chamber/death of chicks (5 nests on 3 different streams in 3 breeding seasons). The temperature curves showed the laying of the eggs, the start of incubation, the successful flight out of the nest chamber or the death of the chicks in the nest chamber. It was not always possible to determine exactly when the chicks hatched from the temperature data.