First evidence of abnormal behaviour of Mus spicilegus obtained in the wild from Slovakia.

In this study are presented six cases of abnormal behaviour based on injured individuals of Mus spicilegus from northern border of the species’ range. The material consistent of six individuals caught during autumn-winter season 2020 in field biotope on south-eastern Slovakia. Determination by morphological traits and subsequent dissection confirmed that all trapped mice were subadults. The cause of the damage found in distinctly bite was aggressive behaviour by other individuals or selfmutilation. There were three main types of damage: (1) incomplete infanticide (2) cannibalism and finally (3) self-mutilation. The findings presented in this study display the first documented abnormal behaviour in the mound-building mouse obtained in the wild.