Résumé: The European hamster (Cricetus cricetus) is one of the most endangered mammal in Europe. In France, less than 800 individuals currently inhabit farmlands of Alsace (i.e. Northern France). However, despite the specific actions undertaken since 2000 in favor of hamsters’ conservation, the French population is still declining and we are lacking precise information on the causes of this decline. Two main issues have been emphasized, namely a decrease in the reproductive success of the species and an increase in the predation rate, both being directly correlated with the generalization of intensive crop monoculture. However, the underlying mechanisms responsible of the observed decrease in the reproductive success remain to be fully investigated. Furthermore, we are still lacking solutions to reduce the predation risks of this species, especially during dispersion throughout wildlife underpasses, in which important predation rates have been recorded. Given that farmland species are often restricted to monotonous diets, we first investigated the nutritional effects of crops on hamsters’ fitness to understand how it could affect its reproduction. Then, to improve hamsters' dispersion, we developed a device (i.e. a sub-tunnel) to limit predation occurring in wildlife underpasses. The main results of this work highlight that elevated corn consumption is severely reducing hamsters’ reproduction because of a major deficiency in vitamin B3, responsible of high rates of maternal infanticides. We then found that crop associations such as corn-sunflower and wheat-soybean are nutritionally favorable to hamsters. These crop associations are therefore currently implemented in Alsace as a conservation measure for this species. Regarding the device to limit predation in wildlife underpasses, our results reveal that hamsters use it to avoid predators, but also that it is favorable to many other rodents (e.g. shrew and voles). This work therefore provides new insight on the decline of this farmland rodent and brings solutions that should not only benefits hamsters, but also farmland wildlife as a whole.
Contact: Cristian PASQUARETTA, EXPLAIN team, CRCA