The study of personality traits could reveal new links between behaviour and population ecology and evolutionary and developmental biology. Our study aimed to broaden the existing research by investigating the impact of personality traits on food preferences for forest tree seeds in two rodent species: the bank vole (Myodes glareolus) and the yellow-necked mouse (Apodemus flavicollis). Under laboratory conditions, behavioural parameters were evaluated in 33 individuals. Using LMM, we calculated the intercepts (considered to represent personality trait) for each individual in freezing and exploration duration (latency reaching the farthest point of the test box). For the preference test, seeds of several typical forest tree species were selected: common hornbeam, European beech, Norway spruce, Scots pine, wild cherry, common oak and small-leaved lime. Ivlev's electivity index (IEI) was calculated for each individual and seed species. The testing day was a significant variable in all GLMMs (seven tree seeds). In spruce, pine and lime seeds, the clear positive selection at the beginning decreased during the test; in hornbeam and oak, the selection was the opposite. In five models, the personality trait (exploration duration), and in two models for oak and lime, rodent species, were significant variables. Personality traits can create structured food niches.