The current range and distribution of the common hamster, Cricetus cricetus in Poland was established. The range of the species has dwindled substantially in the course of just 30 years and the process is still going on. The Polish populations are isolated from the Belarussian, Czech and German ones, there is low probability of some exchange with Ukrainian hamsters. Moreover, two main areas of hamster distribution in Poland are isolated from each other. In view of the marked shrinkage and fragmentation of the range, we propose changing the status of this species in Poland from unknown (DD) to endangered (EN).
An isolated population of the common hamster, forming the western border of the species range in Poland was analysed by the use of 16 microsatellite loci and the mtDNA control region in two consecutive generations. The genetic diversity and the effective population size in this population are low. We found the evidence for ancient bottleneck in this population, but the results of tests for recent reduction of Ne were ambiguous. However, population functions properly i.e. it is in HW equilibrium, Fis and relatedness coefficients do not indicate inbreeding. It indicates that even isolated and small populations of the common hamster have good chance of survival on the condition of the protection and restoration of the habitats. Moreover, the sexrelated differences in dispersal in the common hamster were demonstrated through the relatedness analysis.