Carrying and Hoarding We have seen that, when wild rats have made their way to food, they may take the food under cover before eating it. Carrying food under cover may happen even when the rats have been deprived of food for some time. Wheat grains are taken away in mouthfuls; even a rat of medium weight will take six to eight grains at a journey; a large rat takes more, and may be seen shovelling them rapidly into his mouth until the cheek pouches are full. Under cover, the grains are disgorged and eaten one at a time. This behavior no doubt helps to protect rats from predators. Sometimes food is taken to a nest or burrow and deposited without being eaten. Other objects, such as stones, cakes of soap, bits of wood, and much else may be accumulated in the same way. We have no explanation of this behavior, and it has been largely ignored in experimental studies of hoarding. In stable colonies of wild rats kept in large cages, food cubes are sometimes removed as soon as they are put in the food boxes, and scattered on the floor or taken to the nest boxes. Calhoun, from a study of wild rats in a large enclosure, concluded that most rats store food in their burrows, but especially those which have been mildly attacked by other rats. He reports also that rats which had been severely attacked took food to scattered points nearby and then paid no further attention to it. He suggests that nevertheless this behavior has a biological function, since scattering food makes it more easily accessible to rats living at some distance form the main source. This hypothesis is no proved but, if it is true, scattering the food would favor the growth of a colony by reducing conflict. Hoarding occurs also in tame rats, and in them it has been the subject of many experiments, of which the early ones have been well reviewed by Munn. It is a common observation that tame rats, given objects such as food cubes in an open container, at once pick them up and scatter them around the cage. In a cage with a covered refuge they tend to accumulate objects in this "home" box. Morgan and his colleagues found that this happened especially if the rats had recently been deprived of food for a time. This is not a direct result of hunger; the hoarding does not begin as soon as the rat is hungry, and it goes on long after the rat has been able to eat its fill - sometimes even for twelve weeks; and the pellets are typically not ate, but merely deposited in the living cage. The fact that pellets are collected in the nest suggests that it is their presence which constitutes a consummatory state: that is, that the goal of the behavior is the hoard itself. If this is so, removal of the pellets as they are brought back should increase the number brought in while, presumably, deliberately stocking the home cage with them ought to inhibit the behavior. The result of removing pellets as they are brought in varies. If the rats are not hungry, hoarding occurs wether the cubes are removed or not; but if they are hungry, removal of the cubes during preliminary training in the cage leads to an appreciable reduction in the number of cubes hoarded in a given time when this is subsequently tested. Thus the inhibitory effect of removal of pellets depends on the extent to which the rat needs food at the time when it first experienced the hoarding situation. "Disappointment" at this stage leads to subsequent decline in the impulse to carry out an act which has proved fruitless on previous occasions. Source: the book "The Rat: A Study in Behaviour" by S.A. Barnett