Taiwan is a mountainous island with the steep Central Mountain Range along the longitudinal axis and the highest peak almost 4000 meters. Nearly three-quarters of the area of Taiwan are at an altitude above 1000 meters. The Formosan wood mouse (Apodemus semotus) is the endemic wood mouse that generally resides in the central and southern highlands of Taiwan. Formosan wood mice are extensively distributed between 1400 and 3700 meters, and these mice are rare at the elevations above 3600 meters and below 1500 meters. Several studies show that wood mice worldwide exhibit these behavioural differences compared with the common laboratory mouse. However, whether the exploratory behaviours in Formosan wood mice were different to those in common laboratory C57BL/6 mice is unclear. Whether behavioural responses, corticosterone levels, and central dopaminergic activities of Formosan wood mice contribute to these instinctive behaviours is also unclear. The present study used the behavioral tests to study this issue. High locomotor and exploratory behaviours were highly correlated with corticosterone levels after acute mild restraint stress in male Formosan wood mice. The anxiolytic, diazepam, reduced the high locomotor and exploratory activity and corticosterone levels and central dopaminergic activities in male Formosan wood mice. Taken together, these results showed that male Formosan wood mice had higher activity and exploratory behaviours which might be related to the higher corticosterone levels and higher central dopaminergic activities.