Original investigationDiurnal surface activity of the Ciscaucasian hamster (Mesocricetus raddei) in the field

Monitoring daily activity patterns of animals in the field and in captivity often revealed different results. For example, Syrian hamsters Mesocricetus auratus showed diurnal surface activity in the field, but nocturnal patterns in the laboratory. The aim of our study was to monitor the field activity of a close relative of this species, the Ciscaucasian hamster Mesocricetus raddei from Dagestan. Using the radio-frequency identification (RFID) technique we were able to obtain field data from 20 Ciscaucasian hamsters. In contrast to the data obtained in captivity where the Ciscaucasian hamsters were active mainly at night, they showed a diurnal activity pattern in the field, i.e. animals were observed on surface between sunrise and sunset. Discussing the putative causes of the different activity patterns, we are focusing especially on ecological constraints and advantages. Also, we stress the necessity of more field observations.