Assessing hoarding in mice.

Hoarding is a species-typical behavior shown by rodents, as well as other animals. By hoarding, the rodent secures a food supply for times of emergency (for example, when threatened by a predator) or for times of seasonal adversity such as winter. Scatter hoarding, as seen typically in squirrels and birds, involves placing small caches of food in hidden places, generally underground. Most rodents, however, hoard a supply of food in or near the home base--for example, in 'larders' near the sleeping quarters in a burrow. In the laboratory, measurement of hoarding involves simply weighing the food transported into the home cage from an external source, but the route to that source must be secure and animal-proof; for example, there should be no holes large enough to permit escape of a mouse, and no weak points that could be enlarged by gnawing. A suitable and easily constructed apparatus is described in the protocol. Hoarding has been shown to be sensitive to brain lesions and pharmacological agents, and is a suitable test for species-typical behavior in genetically modified mice.