Many common research animals will make a nest when appropriate nesting materials are available.
For some animals, nest-building is a reaction to breeding; for others, nesting is just a normal activity. For example, hamsters will make elaborate tunnels if the bedding is deep enough. Guinea pigs do not nest, even during pregnancy and parturition. Observing mice, you can also note how much time animals spend tending their nest, rearranging and cleaning both the nest and surrounding area.
Consider the types of beddings and nesting materials offered to animals. A good bedding material should be hypoallergenic, non-nutritive, absorbent and dust free. Additionally, it should be non-toxic and pathogen free. The function of bedding is to provide warmth, privacy, safety, protect and contain young and keep animals dry by absorbing urine. Some animals will store feed in the bedding. It maintains the environment of the cage and contributes to animal welfare by allowing the animal to behave in a natural way.
There are many types of beddings and nesting materials on the market; sometimes this leads to confusion in selection. Bedding can be natural materials such as wood or corncob, or paper products. Bedding should not contain oils that can interfere with research results. There are beddings that provide additional enrichment by allowing the animals to spend time shredding, unraveling, fluffing up or otherwise interacting with the bedding material to create an acceptable nest.