Seasonal and diel activity patterns of small mammal guilds on the Pannonian Steppe: a step towards a better understanding of the ecology of the endangered Hungarian birch mouse (Sicista trizona) (Sminthidae, Rodentia)

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.

Genetic variation in the Sicista subtilis (Pallas, 1773) species group (Rodentia, Sminthidae), as compared to karyotype differentiation

Genetic variation in chromosomally polymorphic Sicista subtilis complex and related Sicista betulina species group was analysed using two mitochondrial markers (COI and Cytb). The S. subtilis group is shown to include six lineages, five of which correspond to species currently recognized based on cytogenetic and genetic data: Sicista nordmanni, Sicista trizona, S. subtilis sensu stricto, Sicista severtzovi and Sicista cimlanica. A previously unknown genetic lineage of S. subtilis was found in the North Caucasus. The existence of two divergent lineages within Sicista strandi is supported. It is suggested that the speciation rate in Sicista was strongly affected by rapid chromosomal evolution.