Temporal activity differences facilitate species’ coexistence by reducing interspecific competition. Such patterns can be studied via diel activity analysis, but obtaining data in cryptic mammals is difficult. We investigated the annual and diel activity pattern of such a small mammal, the endangered Hungarian birch mouse (Sicista trizona trizona), in its only known habitat. We employ trail cameras for the first time to reveal the diel and annual activity of a sminthid species. Data acquisition included the spring and summer seasons between 2019 and 2022 and was extended to detect the activity overlaps with other common coexisting rodents and shrews. The diel activity results rely on 581 detections of S. trizona over 5670 trap-nights of camera trap deployment characterising also activity pattern of the small mammal community in this Central European grassland ecosystem. S. trizona was not recorded during the day but was active at dawn and night, and in comparison with other coexisting species, its activity level was high. The presumed cold sensitivity was not confirmed as we detected activity at −6 °C. Diel activity peaked in early May in the mating season. Although the diel activity pattern of co-occurring small mammal species was also nocturnal, activity overlaps were relatively high suggesting that temporal niche partitioning is limited within the habitat. Our work provides the first insight into temporal overlaps within a small mammal community in a natural European grassland, moreover, also the first documented research on the activity pattern of a sminthid in its natural habitat.

时间活动差异通过减少种间竞争促进物种共存。这种模式可以通过昼夜活动分析来研究，但很难在神秘的哺乳动物中获得数据。我们调查了这种小型哺乳动物——濒临灭绝的匈牙利桦树鼠 ( Sicista trizona trizona ) 在其唯一已知的栖息地中的年度和昼夜活动模式。我们第一次使用跟踪相机来揭示一个小动物物种的昼夜和年度活动。数据采集​​包括 2019 年至 2022 年的春季和夏季，并扩展到检测与其他常见共存啮齿动物和鼩鼱的活动重叠。diel 活动结果依赖于对S. trizona的 581 次检测超过 5670 个陷阱之夜的相机陷阱部署也表征了这个中欧草原生态系统中小型哺乳动物群落的活动模式。S. trizona白天没有记录，但在黎明和夜间活动，与其他共存物种相比，其活动水平较高。由于我们在-6°C 检测到活性，因此未证实假定的冷敏感性。Diel 活动在交配季节的 5 月初达到顶峰。尽管同时出现的小型哺乳动物物种的昼夜活动模式也是夜间活动，但活动重叠相对较高，表明时间生态位划分在栖息地内是有限的。我们的工作首次深入了解了欧洲天然草原上一个小型哺乳动物群落的时间重叠，此外，这也是首次记录在其自然栖息地活动模式的研究。