A small family unit of house mouse (Mus musculus) with anomalous colouration in Slovakia

In this paper, a small family unit (i.e., deme) of the house mouse (Mus musculus) from south-eastern Slovakia is presented, where thirteen individuals exhibited anomalous colouration with signs of flavism. The mice were trapped over seven days (14-20.1.2025) during the winter season in the garage of a family house in the countryside. In total, 23 individuals were obtained (12 males, 11 females). Morphological determination and subsequent dissection confirmed that the trapped mice belonged to three age classes: 8 adults, 2 subadults, and 13 juveniles. The dorsal fur for thirteen mice was yellow (or beige), with slightly darker fur along the middle of the back; the auricles, feet, and tail were light yellow; and the colouration on the belly ranged from light to white. These findings are important not only in terms of colour anomalies but also in terms of genetics.