Developing a nest box data logger for dormice: a case study of wild hazel dormice (Muscardinus avellanarius)

Abstract We present the design and application of the Dormouse Data Logger Generation 3 (DDL3), a novel, programmable and modular monitoring system integrated into a standard nest box for dormice. The logger is recording the nest chamber through various sensors. Incorporating multiple power-saving strategies, the system achieved battery runtimes of over one month, enabling extended monitoring with minimal disturbance. It has been continuously deployed in the field since 2023, demonstrating stable operation under variable environmental conditions. The data collected from a single nest box during the 2024 season are presented here. The DDL3 provided a reliable record of post-hibernation activity in a nest box and enabled detection of seasonal fluctuations in body mass of hazel dormice. Camera, scale and motion-sensing functions supported recognition of torpor events. In addition, the camera recorded behavioural data, documenting cooperative nest construction and rearing offspring. These capabilities enable continuous, non-invasive monitoring of the seasonal dynamics of hazel dormouse behaviour, including pre-hibernation activity. This demonstrates the DDL3’s suitability for high-resolution wildlife monitoring and conservation studies.