Kapusta, J., Kruczek, M., Pochroń, E. et al. 2022. Welfare of encaged rodents: Species specific behavioral reaction of voles to new enrichment items. Applied Animal Behaviour Science 246, 105522.

The enrichment of the environment of captive animals is one of the methods applied to reduce stress of the animals and to assure their proper welfare. However, placing objects in a limited space of a cage does not always have to stimulate positive responses. We conducted an experiment to investigate how universal the reaction of animals to new elements is, especially in case of wild animals. Experimental groups of two species of voles, bank vole (Myodes glareolus) and common vole (Microtus arvalis) kept singly or in trios in same-sized cages, were presented with a gnawing brick and a tunnel. Their behavior was recorded in 30-min periods, categorized to ‘stereotypic’, ‘eating and drinking’ and ‘other behavior’ and compared with the control. Time spent on stereotypic behavior was reduced significantly after the placement of elements only in case of bank vole but not in common vole. Moreover, the latter species was less interested in new elements, exhibited significantly more stereotypies in their presence than in barren cages and housing with conspecific animals significantly enhances stereotypies. Bank voles discriminated between the elements placed in their cages and were observed more often at a tunnel than at a brick, whereas the shape of the elements seemed neutral to common voles. Placing and replacing new elements in cages is an important procedure related to enriching the environment of rodents in the laboratory. Our results indicate that even closely related rodent species may exhibit contrasting behavioral responses to new environment enriching items. We conclude that ensuring best breeding conditions for animals cannot be based on uncritical application of procedures verified for other species.