All things considered? Alternative reasons for hamster extinction

Abstract In 2002 a pest biologist (LEIRS 2002) calculated the survival chances of the European hamster (Cricetus cricetus) according to data provided by participants of the meeting of the International Hamster Workgroup in Tongeren. His model was based predominantly on demographic data as birth rates and predicted that the European hamster will be extinct in Western Europe within the next 50 years. Since then, the mean number of litters females raise in a year has diminished from 2-3 to 1-2. It is thus to be feared that the remaining time is only half as long as predicted and extinction might occur around 2030. However, since then hamster protection measures have improved considerably and two major milestones have been reached: (1) we are able to breed captive hamsters in a sufficient number and (2) most released hamsters survive long enough to reproduce once. Thus, at the present state we can claim that the hamster won.t go extinct as long as such breeding and releasing programs are in place. However, we haven.t achieved a state yet at which it is clear that the hamster will survive with its own means when such programs are stopped. To work on this will be the task of the coming years. This review might be a starting point for that. It reflects on which other factors possibly impair the survival of European hamster populations besides some aspects of modern agriculture, thus it searches for parameters which are not yet considered in conservation programs. Historical data as well as observations and research data from other species are reviewed. Additionally, new insights from the subterranean life of European hamsters in outdoor terrariums are presented, which suggest that the soil as habitat might need more attention in conservation. However, this conjecture can provide only new ideas, which still have to be confirmed by research. The intention is to spark a lively discussion on such potential alternative reasons for the decline of European hamsters, whether some of them are worth being investigated and whether we overlooked something. There is not much time left.