As a result, they often show stereotypies, defined as the repeated performance of the same behaviour without apparent goal or function. In farm and zoo animals, stereotypies have successfully been treated by supplying the animals with an appropriate set of artificial environmental stimuli, also called environmental enrichment. We analyse the causes of this behaviour by adding specific enrichment factors to the standard housing conditions or by modifying the handling of the gerbils during breeding. Afterwards we observe selected animals weekly from their birth to adulthood to quantify the frequency and duration of bouts of stereotypic behaviour. In the wild, gerbils live in vast subterranean burrow systems which provide shelter against the climate and predators.
Standard laboratory cages lack a burrow-like structure into which the animals can retreat.
In such a situation, the gerbils might be highly motivated to attempt to create a burrow by digging. All their efforts remain unsuccessful, which might lead to stereotypical repetition of digging motions, permanent frustration or even chronic stress in the gerbils. We tested this hypothesis by adding an artificial burrow consisting of an opaque nest chamber accessible through a tunnel. Under such conditions, stereotypic digging was significantly reduced. Experiments showed, however, that neither of these factors had an influence on the development of bar-chewing.